Every year, we contribute numerous articles to the scientific literature.
Publications led by the Project Seagrass team are highlighted in bold.
Project Seagrass is an Independent Research Organisation, recognised for producing high-quality science that advances seagrass conservation, informs policy, and supports action around the world.
Since our inception in 2013, we have led and contributed to nearly 120 peer-reviewed scientific publications, helping to build the evidence base for the protection, restoration and long-term stewardship of seagrass meadows.
Our research spans the ecological, social and policy dimensions of seagrass conservation. This includes pioneering work on the role of seagrass meadows in supporting food security, small-scale fisheries and coastal livelihoods, as well as studies on citizen science, nutrient pollution, restoration methods, ecosystem services, biodiversity, and social-ecological systems.
Through this work, we aim to ensure that decisions about seagrass are grounded in robust science, shaped by local knowledge, and connected to the needs of people and planet.
Use the year tabs below to explore our publications.
Project Seagrass is an Independent Research Organisation, recognised for producing high-quality science that advances seagrass conservation, informs policy, and supports action around the world.
Since our inception in 2013, we have led and contributed to nearly 120 peer-reviewed scientific publications, helping to build the evidence base for the protection, restoration and long-term stewardship of seagrass meadows.
Our research spans the ecological, social and policy dimensions of seagrass conservation. This includes pioneering work on the role of seagrass meadows in supporting food security, small-scale fisheries and coastal livelihoods, as well as studies on citizen science, nutrient pollution, restoration methods, ecosystem services, biodiversity, and social-ecological systems.
Through this work, we aim to ensure that decisions about seagrass are grounded in robust science, shaped by local knowledge, and connected to the needs of people and planet.
Use the year tabs below to explore our publications.
Every year, we contribute numerous articles to the scientific literature.
Publications led by the Project Seagrass team are highlighted in bold.
The world's oceans are in a severe state of degradation, yet our understanding of that degradation is often based on changes observed only in the past 20–50 years. This narrow view leads to marine conservation efforts that aim to preserve already degraded ecosystems, shaped by shifted ecological baselines. Historical ecology offers a broader perspective by examining past environments and biodiversity. In this study, we analyse historical records including maps, reports, and written accounts to explore the transformation of estuarine and coastal environments in Wales, a key centre of the Industrial Revolution. Our findings reveal widespread historical modification: 33 of the 42 Welsh estuaries studied show major alterations, including land reclamation, embankment construction, and channel rerouting. Some estuaries were completely erased, and islands no longer separate from the mainland. The resulting disruption of sediment dynamics, water quality, and habitat complexity has had long-term impacts on biodiversity and ecosystem services. We hypothesise these changes led to the widespread loss of critical habitats such as salt marshes, oyster beds and seagrass meadows, which support marine biodiversity and ecosystem health. Wales is only at the start of a habitat restoration journey, and the nation can learn from other regions of the world where restoration has successfully improved ecosystem function. But Wales faces a legacy of degradation with few, if any, ‘low-impact’ baselines remaining. We argue that current restoration efforts in Wales should not aim to return ecosystems to an imagined baseline or historical state. Instead, restoration should be reimagined with modern goals focusing on enhancing biodiversity, ecosystem resilience, and human well-being through the lens of a changing climate. Wales' estuarine environments, though heavily modified, present unique opportunities. By recognising the true extent of historical change, we can move beyond outdated notions of conservation and embrace degraded ecosystems as foundations for future recovery.
Near-shore marine habitats are well-documented as diverse and productive social-ecological systems; their degradation and loss have led to growing interest in marine restoration. However, the literature offers limited consideration of the interactions between these projects and stakeholders and local communities. We present a case study showing how a stakeholder engagement strategy ultimately led to the co-production of a marine restoration project among scientists, stakeholders and local communities. Alongside biological recovery, we present the complex social, logistical and ecological lessons learned through this stakeholder engagement strategy. Principally, these relate to how the success of the project hinged on the point at which the project was co-developed with the input of local communities and strategic stakeholders, rather than in a disconnected, independent manner. This project demonstrates that for marine restoration to truly be successful, projects need to engage and work with local people from the outset, through open and early stakeholder engagement and particularly with the people possibly impacted by its presence. Projects need to be created not just for ecological design but also to be relevant and beneficial to a wide range of people. What we show here is that co-producing a project with communities and stakeholders can be complex but lead to long-term sustainability and support for the project, with strong ecological outcomes. To achieve this requires an open and flexible approach. Finally, this work showcases how the restoration of marine habitats can be achieved within a social-ecological system and lead to benefits for people and the planet.
Seagrass restoration is increasingly guided by habitat suitability models, yet restoration outcomes depend on more than biophysical suitability alone. In coastal social-ecological systems, fishers and anglers hold fine-scale, time-integrated knowledge of habitat condition, human use, and local constraints that are rarely incorporated at the outset of restoration planning. Here, we tested whether fisher and angler knowledge could generate a spatially explicit basis for seagrass restoration site selection along the southern Welsh coastline, United Kingdom. Using participatory mapping and a Wisdom of Crowds approach, 33 coastal resource users identified locations perceived as suitable for seagrass restoration and areas where restoration should be avoided. Weighting responses by regional participation and converting them into kernel density surfaces, we tested whether participatory-derived suitability predicted independently observed seagrass occurrence and assessed stakeholder perceptions of seagrass benefits. Participatory mapping revealed coherent hotspots of perceived restoration opportunity in sheltered bays and estuarine environments, whereas avoidance areas clustered around ports, sediment-influenced estuaries, and high-use tourism locations, indicating that participants integrated both ecological opportunity and human-use constraints. Net suitability was a strong predictor of seagrass occurrence, demonstrating close correspondence between aggregated local knowledge and observed seagrass distribution. Perceptions of seagrass restoration were broadly positive, with strong agreement that seagrass benefits marine life and the wider environment. Our findings show that fisher and angler knowledge can generate spatially coherent and ecologically meaningful information for restoration planning. Rather than acting as a simple substitute for habitat suitability modelling, participatory mapping functions as a social–ecological diagnostic layer, identifying areas of opportunity, constraint, and potential conflict. Integrating local knowledge early in restoration planning can improve site selection, guide choices between protection, passive recovery and active restoration, and strengthen legitimacy, stewardship, and long-term support for seagrass recovery.
Seagrass meadows are globally important coastal habitats support high biodiversity and underpin key ecological functions, yet they are increasingly threatened by eutrophication. While the impacts of nutrient enrichment on seagrass condition and productivity are well established, its influence on the structure of associated epifaunal communities remains less clearly understood, particularly across broad spatial scales. In this study, we examined epifaunal assemblages associated with Zostera marina meadows at 16 sites spanning lagoon, estuarine, coastal, and island environments around the British Isles. Using standardised field sampling in combination with mixed-effects modelling, we investigated how variation in environmental setting within the seascape, seagrass morphological traits, and leaf tissue nutrient concentrations (nitrogen and phosphorus) shaped patterns of epifaunal abundance, richness, and community composition. Epifaunal assemblages exhibited strong spatial heterogeneity, with local site-level environmental conditions explaining a large proportion of variation in community structure. While broader habitat categories provided some explanatory value, seascape-level fine-scale environmental context consistently emerged as an additional driver. Seagrass morphological traits, including leaf length, width, biomass, and epiphyte cover, had limited influence on epifaunal richness and abundance, suggesting that small-scale habitat complexity was not the primary determinant of biodiversity within these meadows. In contrast, nutrient availability, particularly nitrogen enrichment, had a marked effect on epifaunal diversity. Higher nitrogen concentrations were generally associated with reduced epifaunal abundance and richness when standardised by leaf area, consistent with detrimental ecological effects of eutrophication. However, these relationships varied among habitat types: moderate nitrogen levels corresponded with increased diversity in estuarine and island sites, whereas coastal and lagoon meadows showed stronger declines under enhanced enrichment. Phosphorus exhibited especially negative effects in lagoon environments. These findings demonstrate that elevated nutrient concentrations alter seagrass-associated biodiversity in context-dependent ways. Effective management and restoration will therefore require site-specific nutrient reduction and monitoring strategies that reflect local ecological conditions rather than uniform regional targets.
Marine heatwaves (MHWs) are increasing in frequency and intensity as a result of climate change, yet their implications for ecosystem recovery and habitat restoration remain poorly understood. Here, we document how an acute spring 2024 MHW likely contributed to the failure of a large-scale intertidal Zostera marina restoration effort in the Irish Sea. Across two neighbouring bays (∼50 km apart) in North Wales (UK), over 1.1 million seeds were sown in 2023–2024. Seagrass plantings in Bae Caergybi survived through 2024; however, all plantings in Bae Tremadog failed. Satellite-derived and in situ environmental data revealed that the Bae Tremadog failure coincided with a rapid-onset MHW, during which sea surface temperatures increased by ±3.5 °C in seven days and intertidal sediment temperatures exceeded 30 °C during low tides. This thermal extreme was followed by a sharp decline in salinity and an increase in wave exposure, creating a compounding multi-stressor event. By contrast, Bae Caergybi experienced cooler and more stable abiotic conditions, enabling seedling establishment and overwinter survival. Long-term records indicate increasing mean temperatures and high interannual variability at the failed sites, suggesting that suitable restoration windows are narrowing as the climate warms. Our findings provide one of the first documented cases of a MHW directly undermining marine habitat restoration in Northern Europe. Recognising and forecasting climate-driven extreme events and prioritising ‘refugia’ sites with greater abiotic stability will be critical for improving the resilience and success of future marine restoration initiatives.
Seagrasses perform various critical functions within social–ecological systems, though populations have declined drastically. Restoring seagrass is crucial, requiring holistic consideration of ecological and human dimensions. To date, biophysical factors predominantly guide restoration and marine spatial planning (MSP). Sociocultural data underpin optimal and just restoration design, but remain a “missing layer” in MSP. To address this gap, we combined participatory mapping and ground-truthed remote sensing to map seagrass distribution, human activities, and place values in Sanday, UK. Local knowledge guided in situ surveys, co-producing Sanday’s first scientific seagrass records. We “found” two meadows absent from current seagrass modelling, mostly within protected areas, and highlighted corresponding human activities (notably shellfisheries) and values (humanistic and scientific). We propose three restoration priority sites, given seagrass extent, habitat protection, and compatible activities and values. This study demonstrates potential for transdisciplinary mapping to improve restoration planning, addressing the missing sociocultural layer and key gaps within MSP processes.
To effectively manage and protect ocean life and the people who depend on it, we need coordinated, comparable observations of ocean biodiversity. Seagrass cover and composition is an essential ocean variable (EOV) of the Global Ocean Observing System because seagrasses are the foundation of coastal ecosystems worldwide, and support diverse marine life and ecosystem services. We present guidelines for collecting and reporting seagrass data that fulfill specifications for the EOV, including three priority measurements to maximize compatibility among data sets: seagrass cover, species composition, and areal extent, with priority environmental variables for interpreting changes in status and condition. To promote interoperability, we present a standard format for seagrass EOV data and metadata. These guidelines will enable better monitoring and assessment of seagrass ecosystems, facilitate syntheses, inform the Kunming–Montreal Global Biodiversity Framework headline indicator “Extent of natural ecosystems,” and support evidence-based conservation and sustainable development.
Muddy continental shelf sediments act as important sinks for atmospheric CO2 by accumulating organic matter, a small fraction of which is buried and stored as organic carbon (OC) over long timescales. Quantifying long-term OC burial in shelf sediments is critical for understanding their role in climate regulation; however, this remains difficult due to limited age-resolved data and the challenges of determining sediment accumulation rates and temporal changes in OC content. To address this, we quantified age-resolved OC storage over the past two centuries in the upper 50 cm of the Western Irish Sea Mud Belt (WISMB) by measuring depth-resolved OC content and sediment accumulation rates. The OC content (0.15%–1.62%), OC storage (1.30–15.15 gC cm−3), and sediment accumulation rates (0.26–0.37 cm yr−1) vary both spatially and temporally, with the highest OC accumulation and burial occurring in muddier, deeper-water sediments. Between 53% and 91% of the OC accumulated in the surface 2 cm over the past 8 years (17.09–39.47 gC m−2 yr−1), and 60%–68% of the OC accumulated in the upper 10 cm over the past 38 years (21.90–51.13 gC m−2 yr−1), remains buried for more than 100 years (14.03–33.50 gC m−2 yr−1). These rates are comparable to those reported for other muddy continental shelf regions, including mud patches, coastal fjords, and glacial troughs.
1. Nature-Based Solutions, green-finance instruments and policies are now routinely constructed around carbon sequestration/storage (CSS) and nutrient bioremediation (NB). This integration builds on how Market-Based Instruments (e.g. payments-for-ecosystem-services) are regularly used in policies focused on terrestrial ecosystems. In marine and coastal systems poor understanding of CSS/NB biophysical processes and impacts of ecosystem quality/stressors, combined with methods and governance framework knowledge gaps, generate substantial uncertainty in outcomes. Reductions in output confidence preclude integration into Nature-Based Solutions, stifling market-based investment centred on conserving and restoring temperate coastal ecosystems. 2. To navigate this complex, rapidly evolving area, researchers from six continents engaged in a Priority Setting Exercise to generate 25 questions that, if answered within 10 years, will increase robustness, scalability and applicability of CSS/NB data across regions and ecosystems. We then used a modal analysis across five categories (time, geographic scale, technology complexity, cost and policy relevance) to expedite research-investment decisions. 3. Questions (numbers in brackets) were organised across six themes as follows: maps/quantitative evidence/long-term data (3), Processes/variability (6), Connectivity (2), Anthropogenic impacts (4), Methods/standards (6), Governance/conservation (4). 4. Questions under methods/standards and governance/trading schemes themes were generally identified to be the cheapest to answer and quickest to complete, whilst still having considerable geographic and policy relevance. 5. Policy implications: Identifying the enabling conditions for more efficient and successful approaches will greatly improve our understanding of ecosystem services. Together, these answers will then deliver the decision-grade data necessary to strengthen green-finance opportunities and address urgent climate and pollution (nutrient) crises.
Seagrass meadows are vital coastal ecosystems that embody the One Health paradigm, connecting human, animal, and environmental well-being. These highly productive habitats offer critical ecosystem services: They store carbon, stabilize shorelines, and filter pollutants and pathogens, bolstering climate resilience and water quality. As foundation species, seagrasses support diverse marine life and underpin global fisheries that provide nutrition, livelihoods, and cultural sustenance for coastal communities. Microbes enhance this function by actively reducing pathogens and detoxifying sediments, showcasing how microscale processes support broader societal health. However, anthropogenic pressures, especially nutrient pollution, are driving global decline. Case studies demonstrate that coordinated management and restoration can reverse this degradation and enhance ecosystem and social benefits. Integrating seagrass conservation into One Health frameworks highlights the need for proactive, multisectoral approaches. Protecting and restoring these meadows is a critical investment in resilient coastal communities, sustainable fisheries, and the overall health of human and planetary systems.
The capacity of natural systems to deliver multiple functions and services simultaneously is critical for human well-being, yet this concept of multifunctionality has rarely been applied to the nutritional role of nature. Coral reef fisheries are known to supply multiple essential nutrients, but the contribution of adjacent habitats to alleviating human malnutrition remains poorly understood. Here, we apply a multifunctionality index to quantify the micronutrient potential of seagrass- and reef-associated fish assemblages across a 3,000-km coastline in East Africa. Considering suites of micronutrients as an integrated system, we show that seagrass-associated fish assemblages are, on average, 1.6 times more nutritionally multifunctional than reef-associated assemblages, despite supporting lower total biomass. This nutritional advantage is even more pronounced when focusing on key regional fishery species. Our findings identify seagrass meadows as underrecognized reservoirs of micronutrients with important implications for human health in low- and middle-income countries dependent on small-scale fisheries.
Understanding the long-term effects of bottom trawling on sedimentary organic carbon (OC) is crucial for assessing its role in carbon cycling and climate regulation. Most studies analyse effects on surface sediments (≤10 cm), leaving impacts on deeper sediments poorly resolved. This study investigates how bottom trawling influences sediment OC density (SCD) and OC content within 0–50 cm of the Western Irish Sea Mud Belt, representing sediments deposited from 1860 to 2022. SCD and OC content were lower in intensely trawled areas, declining by 0.031 × 10−2 gC cm−3 and 0.05 wt% per additional swept area ratio (+1 yr−1). OC decreased by 0.007×1 0−2 gC cm−3 and 0.01 wt% for every centimetre into the sediment. Mud content had a significant effect on OC content, but not SCD, whereas Nephrops burrowing did not significantly affect either. These findings support evidence of trawlings potentially long-term negative impact on OC in muddy sediments.
Seagrass restoration is rapidly gaining popularity in the UK. Increased public and political awareness of historic and ongoing declines, along with its value to people and planet, have inspired several restoration projects. However, there remain key bottlenecks in the seagrass restoration process preventing success at scales required to halt declines, let alone to increase habitat coverage. To improve restoration success collaboratively, it is important that those involved in the governance and practice of restoration have shared understanding of what those bottlenecks are and what can be done to overcome them. Here we present insight gathered through semi-structured interviews with individuals working in the governance of seagrass restoration and with practitioners involved in active restoration projects. We highlight the key perceived barriers and discuss potential solutions proposed by those who know the sector best. Some solutions are already happening or emerging in practice, while others remain ambitious ideas that will require strong political and social will, robust funding and time to realise. Now is the time to act to capitalise on the current momentum in the sector and put UK seagrass on a trajectory of net gain, rather than net loss.
Despite being relatively neglected until the early 2000s, seagrass ecosystems are now recognized as critical habitats supporting biodiversity and ecosystem services including carbon sequestration, coastal protection and food supply. In this Review, we discuss the structure and function of seagrass beds, the ways that they support biodiversity and ecosystem services, their dominant threats, and the most promising conservation and restoration opportunities. Seagrass ecosystems support biologically diverse communities, and food web integrity within these communities can reciprocally maintain healthy seagrass ecosystems. Numerous anthropogenic pressures caused persistent declines of 1% to 2% per year in global extent during the twentieth century, but a range of policies, primarily focused on reducing coastal water pollution, have attenuated or reversed losses in some regions. Uncertainty about the global and regional distributions of seagrasses and their trajectories, as well as the high costs of restoration, undermine conservation progress. An escalation in research effort is required to improve projections of seagrass responses to climate change and to identify cost-effective and scalable restoration approaches.
Atlantic saltmarshes are widely recognised as important and productive estuarine habitats, yet their role in supporting fish populations in northern Europe remains understudied. We used fyke and seine nets to assess fish assemblages at 14 sites across two estuaries in Carmarthen Bay, South Wales. Sampling took place in both saltmarshes and unvegetated estuarine shores monthly from October 2023 to September 2024. The age composition of the catch was predominantly juvenile (83 %). Fish density was significantly higher in saltmarshes (5972 ind/ha) compared to unvegetated shores (1806 ind/ha; p < 0.001). Six species were present in saltmarshes across all seasons, including Atlantic herring (Clupea herrangus) and European flounder (Platichthys flesus) not previously documented year-round in UK saltmarshes. Several species, were significantly more likely to be caught within saltmarsh, including lesser sandeel (Ammodytes tobianus) and grey mullet species (Chelon ramada, Chelon labrosus, Chelon aurata), while no species were significantly more likely to be caught in unvegetated shores, demonstrating saltmarshes enhanced nursery function. In total, 19 fish species were recorded in saltmarshes, representing the highest species richness documented for UK saltmarshes. Clear seasonal shifts in community composition were observed, with peaks in European flounder (Platichthys flesus) in May, European bass (Dicentrarchus labrax) in June and Atlantic herring (Clupea herrangus) in July, likely reflecting staggered recruitment strategies that minimise competition during early life stages. These findings provide the first year-round assessment of saltmarsh fish assemblages on the west coast of the UK and highlight the ecological value of saltmarshes in supporting coastal fish communities.
Seagrass meadows play a critical role in biogeochemical cycling, especially in nitrogen and sulphur processes, driven by their associated microbiome. This study provides a novel functional analysis of microbial communities in seagrass (<i>Zostera marina</i>) rhizosphere and endosphere, comparing seedlings and mature plants. While nitrogen-fixing bacteria are more abundant in seedlings, mature plants exhibit greater microbial diversity and stability. Sediment samples show higher microbial diversity than roots, suggesting distinct niche environments in seagrass roots. Key microbial taxa (sulphur-oxidizing and nitrogen-cycling bacteria) were observed across developmental stages, with rapid establishment in seedlings aiding survival in sulphide-rich, anoxic sediments. Chromatiales, which oxidize sulphur, are hypothesized to support juvenile plant growth by mitigating sulphide toxicity, a key stressor in early development. Additionally, sulfate-reducing bacteria (SRB), though potentially harmful due to H<sub>2</sub>S production, may also aid in nitrogen fixation by producing ammonium. The study underscores the dynamic relationship between seagrass and its microbiome, especially the differences in microbial community structure and function between juvenile and mature plants. The study emphasizes the need for a deeper understanding of microbial roles within the seagrass holobiont to aid with Blue Carbon stores and to improve restoration success, particularly for juvenile plants struggling to establish effective microbiomes.
Numerous global maps chart humanities impact on multiple levels of biodiversity, revealing a multitude of pressures across a variety of ecological systems. While useful for identifying the global scale policy changes needed to conserve the world’s biodiversity, they often lack resolution at the scale needed for local management and conservation. While we can broadly speculate the key large-scale drivers that have influenced seagrass populations over the last century, no global map exists that reveals the range and scale of human pressures on seagrass meadows. Using a citizen science database (https://seagrassspotter.org) that comprises of more than 8000 georeferenced points, we use a subset of these map the prevalence of multiple, locally observed anthropogenic threats to seagrass meadows. We find that 50% of human-impacted sites were within areas with designated protection, reflecting 4.4% of the world’s marine protected areas and other effective area-based conservation measures where anthropogenic activities place seagrass at risk. Using vulnerability scores for each human impact, we identify high-risk sites in Columbia, Fiji, Indonesia, Mexico, Mozambique, the Philippines, Sri Lanka, and Tanzania, where multiple pressures likely place seagrass meadows on a trajectory of decline. In doing so, we build on a growing body of research highlighting the vulnerability of coastal ecosystems to human impacts, and at the same time, highlight the role of citizen science in identifying and mapping these threats at the resolution needed for management.
Seagrass meadows continue to be lost and degraded globally. Restoration is one promising and emerging conservation strategy to combat such losses and place seagrass on a pathway to net gain. However, successful restoration methods remain limited to a few species, and geographically constrained, with few experimental trials comparing planting methods across species and seagrass bioregions. This study trialled three seed-based seagrass restoration planting methods in two seagrass bioregions (the temperate north Atlantic and temperate southern oceans). Using two seagrass species Zostera marina and Zostera muelleri this research investigated seed-based planting methods and their influence on the likelihood of seedling emergence, shoot emergence, and seedling growth (i.e. leaf length). Seagrass emergence was observed at 50 % of the experimental sites, with the likelihood of seagrass emergence largely influenced by local site conditions. Each planting method performed variably in relation to species and environmental conditions. Dispenser injection seeding resulted in the highest shoot emergence efficiency of the three methods for Z. marina while biodegradable planting pots and hessian bags were the more favourable methods for use with Z. muelleri seeds. Despite all chosen sites deemed suitable for restoration from habitat suitability models, low seedling emergence suggests that site conditions including wind fetch, redox boundary depth and mud- dominant sediments present specific bottlenecks to seed germination and retention. This work demonstrates the importance of matching seed planting methods to site conditions and species life history traits and highlights the need for greater understanding of mechanisms to overcome germination and emergence bottlenecks in seed-based restoration.
Marine biodiversity is rapidly declining, necessitating global political and financial solutions to prioritize habitat restoration in a “blue revolution.” However, marine and coastal restoration faces major technical, logistical, and resource challenges that are exacerbated by climate change, which must be urgently addressed. Unlike terrestrial restoration, marine efforts lack a long history or well-established methods, resulting in potentially high failure rates and a pressing need for innovation. As scientists and practitioners, we argue that scaling marine and coastal restoration requires policy reform, scientific advancement, and more adaptive regulatory frameworks. Current approaches are constrained by unrealistic ecological baselines and outdated assumptions about environmental stability. Licensing must move beyond recreating past habitats and instead support resilient ecosystems, ecological connectivity, and future colonization pathways. We need to rethink restoration for a changing world, guided by flexible systems that embrace uncertainty, integrate new technologies, and prioritize long-term coastal resilience over short-term fixes.
Seagrass meadows are thought to reduce water column marine bacterial pathogens, with new data from Fiorenza et al. (1) suggesting that this function extends to reducing disease in seaweed cultivation by 75%. As a result, Fiorenza et al. (1) advocate scaling seaweed production within seagrass meadows globally, highlighting benefits to local livelihoods. We argue that this is premature and dangerous for marine biodiversity and wider ecosystem functioning across the ~20.7 million km2 of suitable area. Fiorenza et al. (1) do not consider the holistic nature of the problem that they aim to provide solutions for nor the potential for complex unintended consequences (2, 3). Water quality issues are globally prevalent. Understanding the role of seagrass in reducing pathogens, and how this facilitates and influences other ecological functions and services, is indeed highly important. However, suggestions made by Fiorenza et al. (1) are built on three flawed assumptions: first, that seaweed cultivation and seagrass can co-exist sustainably, two, that the results of their study are ubiquitous to the region, and, finally, that seaweed cultivation positively correlates with sustainable development. First, despite historic and globally widespread seaweed cultivation, limited studies investigate effects on seagrass. In the few locations where studies exist, effects have been negative for seagrass structure and function and for associated biodiversity (4–7). We can only hypothesize the effects (e.g., displacement, entanglement) to seagrass-associated migratory species and megaherbivores that are also culturally significant for Indigenous people. Despite a potentially positive role of seagrass for seaweed production, the ecosystem services provided by seagrass, which are driven by structure, function, and biodiversity, likely suffer under cultivation scenarios. Second, the results of the study do not provide a cause-and-effect relationship between seagrass and seaweed pathogen removal: 1) Fiorenza et al. (1) have not manipulated seagrass presence or conducted a more robust before-after control-impact study, and 2) have not actually measured seaweed pathogen presence or infections. In the best case, their data provide evidence to hypothesize a relationship that requires empirical experimental investigation. Finally, in the context of sustainable development, seaweed cultivation strategies have mixed evidence for success (3, 8). Some evidence suggests that the activity worsens important development identifiers such as income and health, particularly for women (9, 10), and where it has been implemented to reduce fishing pressure, seaweed cultivation has instead increased (and often just displaced) fishing activity. Understanding what trade-offs exist before advocating for large-scale expansion of this and other coastal industries is fundamental. Learning from the past, premature calls to scale oil palm production as a “vehicle to eradicate rural poverty” have been devastating for biodiversity and communities. Given the rapidly increasing threats faced by tropical marine habitats and their need to support coastal resilience to a changing climate, the risks posed by widespread seaweed cultivation to seagrass is high. This may also impact the most vulnerable in communities where the activity is prevalent (2). These complexities warrant further investigation to allow for a more nuanced discussion of short and long-term trade-offs before any scaling can occur.
Temperate coastal marine ecosystems have undergone severe global loss and degradation. We provide a framework for considering ecological connectivity in marine systems and evidence for ecological connectivity across temperate coastal seascapes, developed through expert consensus and structured review. We demonstrate that ecosystem functioning and the delivery of ecosystem services require the existence of a healthy mosaic of coastal habitats, maintained by the exchanges of matter and energy between them. We advocate a seascape approach, that restores connectivity and optimal structure-function relationships, is crucial for successful ecosystem restoration. Consequently, we provide recommendations to deliver seascape restoration of coastal habitats to support the targets set by the 2021-30 UN Decades of Ocean Science and Ecosystem Restoration. Acknowledging the interconnected nature of coastal ecosystems has implications for policy. We identify opportunities and actions to support nature recovery and integrate policy frameworks across climate and biodiversity agendas to achieve international goals for planetary resilience.
Abstract Introduction The structure and function of seagrass habitats are essential for supporting ecosystem services and ensuring ecosystems resilience. However, seagrass ecosystems are continuing to decline globally. Restoration initiatives are increasingly adopted to help curb these losses and accelerate ecosystem recovery. Objectives This study sought to rapidly increase seagrass cover and structural complexity of a fragmented but recovering intertidal seagrass meadow. Methods To do this, we conducted in situ field experiments using four seed‐based restoration planting methods: hessian bags, clay seed balls, dispenser injection seeding (DIS), and planting seedlings. Changes in seagrass cover and structural complexity were monitored for a 6‐month period and compared to natural meadow recovery. Results Our results showed few differences in seagrass cover and structural complexity across the experimental planting methods. DIS showed marginally favorable results compared to other methods at sustaining cover throughout the experimental period. Seasonality was found to substantially influence seagrass traits, with marginal decreases in growth in planted plots observed when seasonal influence was removed. Conclusions These results indicate that both direct seeding and planting seedlings could potentially be used for enhancing seagrass recovery in low density meadows; however, method selection and meadow seasonal dynamics should be given careful consideration to facilitate rapid meadow recovery.
Seagrasses have been entwined with human culture for millennia, constituting a natural resource that has supported humanity throughout this history. Understanding the societal value of seagrass fosters appreciation of these ecosystems, encouraging conservation and restoration actions to counteract historic and predicted losses. This study overviews the plethora of seagrass use in human history, ranging from spiritual and ceremonial roles, direct and indirect food resources, medicines and raw materials, dating back more than 180 000 years. While many past uses have been abandoned in modern societies, others have persisted or are being rediscovered, and new applications are emerging. As these uses of seagrasses depend on harvesting, we also underscore the need for sustainable practices to (re)generate positive interactions between seagrasses and society. Our review contributes to revalue seagrass societal ecosystem services, highlighting ancient and more recent human and seagrass relationships to incentivize conservation and restoration actions.
Embracing local knowledge is vital to conserve and manage biodiversity, yet frameworks to do so are lacking. We need to understand which, and how many knowledge holders are needed to ensure that management recommendations arising from local knowledge are not skewed towards the most vocal individuals. Here, we apply a Wisdom of Crowds framework to a data-poor recreational catch-and-release fishery, where individuals interact with natural resources in different ways. We aimed to test whether estimates of fishing quality from diverse groups (multiple ages and years of experience), were better than estimates provided by homogenous groups and whether thresholds exist for the number of individuals needed to capture estimates. We found that diversity matters; by using random subsampling combined with saturation principles, we determine that targeting 31% of the survey sample size captured 75% of unique responses. Estimates from small diverse subsets of this size outperformed most estimates from homogenous groups; sufficiently diverse small crowds are just as effective as large crowds in estimating ecological state. We advocate for more diverse knowledge holders in local knowledge research and application.
Human society relies on, and interacts with, a diverse assortment of organisms and ecological systems, from the local to the global level. Research and management of these coupled social-ecological systems requires data that speaks to the variety of processes, statuses, and situations defined by them. Effective stewardship is enhanced by interdisciplinary thinking and, critically, access to interoperable data describing human society and governance and ecological and environmental conditions. Such approaches are inherently challenging, especially for those without broad training. In this paper, we propose a workflow harnessing the Social-Ecological System Framework to identify, access, and utilize geospatial data from across a spectrum of social and ecological indicators. We demonstrate the application of this workflow using Tropical Indo-Pacific seagrasses as an example system and in doing so, demonstrate the wealth of available open-data which can support an enhanced understanding of social-ecological system dynamics. With this workflow, we provide a readily applicable tool for use by coastal researchers and managers to support more inclusive social-ecological decision making.
Seagrass restoration efforts have been ongoing for decades, with early innovations dating back to the 1970s. While there has been progress, many projects have high failure rates, but the consensus within the literature is that increasing spatial scale will lead to higher success rates. To achieve scaled-up restoration, innovation in the context of mechanised approaches is required that can reduce the costs and labour-intensive processes and improve reliability. This review paper focuses on the restoration of seagrass meadows and how engineering solutions have been used to help scale up these efforts. The paper examines the different stages within seagrass restoration and how mechanised approaches have been used to date, along with their levels of success or failure. Various stages of restoration are examined, from seed collection, separation, storage, planting, and the biological and environmental engineering challenges associated with upscaling these efforts. The review focuses primarily on Zostera species due to its dominance in the literature, but expands to other species where possible. Although extensive mechanised approaches have been used (e.g. seed planting sleds), a common thread through the studies remains the limited underpinning understanding of the biology to improve the use of these methods and a solid understanding of the relative merits of the use of these techniques. Despite innovations, seagrass restoration is still marked by high failure rates. More interdisciplinary work is required to link biological and engineering solutions to environmental variability for greater restoration success.
ABSTRACT Aim Biogenic structural complexity increases mobile animal richness and abundance at local, regional and global scales, yet animal taxa vary in their response to complexity. When these taxa also vary functionally, habitat structures favouring certain taxa may have consequences for ecosystem function. We characterised global patterns of epifaunal invertebrates in eelgrass ( Zostera marina ) beds that varied in structural and genetic composition. Location North America, Europe and Asia. Time Period 2014. Major Taxa Studied Peracarid crustaceans and gastropod molluscs. Methods We sampled epifaunal invertebrate communities in 49 eelgrass beds across 37° latitude in two ocean basins concurrently with measurements of eelgrass genetic diversity, structural complexity and other abiotic and biotic environmental variables. We examined how species richness, abundance and community composition varied with latitude and environmental predictors using a random forest approach. We also examined how functional trait composition varied along with community structure. Results Total species richness decreased with latitude, but this was accompanied by a taxonomic shift in dominance from peracarid crustaceans to gastropods, which exhibited different sets of functional traits. Greater eelgrass genetic diversity was strongly correlated with both richness and abundance of peracarids, but less so for gastropods. Main Conclusions Our results add to a growing body of literature that suggests genetic variation in plant traits influences their associated faunal assemblages via habitat structure. Because peracarids and gastropods exhibited distinct functional traits, our results suggest a tentative indirect link between broad‐scale variation in plant genetic diversity and ecosystem function.
Combating climate change and achieving the UN Sustainable Development Goals (SDGs) are two important challenges facing humanity. Natural climate solutions (NCSs) can contribute to the achievement of these two commitments but can also generate conflicting trade‐offs. Here, we reviewed the literature and drew on expert knowledge to assess the co‐benefits of and trade‐offs between 150 SDG targets and NCSs within 12 selected ecosystems. We demonstrate that terrestrial, coastal, and marine NCSs enable the attainment of different sets of SDG targets, with low redundancy. Implementing NCSs in various ecosystems would therefore maximize achievement of SDG targets but would also induce trade‐offs, particularly if best practices are not followed. Reliance on NCSs at large scales will require that these trade‐offs be taken into consideration to ensure the simultaneous realization of positive climate outcomes and multiple SDG targets for diverse stakeholders.
Abstract Social‐ecological systems like fisheries provide food, livelihoods and recreation. However, lack of data and its integration into governance hinders their conservation and management. Stakeholders possess site‐specific knowledge crucial for confronting these challenges. There is increasing recognition that Indigenous and local knowledge (ILK) is valuable, but structural differences between ILK and quantitative archetypes have stalled the assimilation of ILK into fisheries management, despite acknowledged bias and uncertainty in scientific methods. Conducting a systematic review of fisheries‐associated ILK research ( n = 397 articles), we examined how ILK is accessed, applied, distributed across space and species, and has evolved. We show that ILK has generated qualitative, semi‐quantitative and quantitative information for diverse taxa across 98 countries. Fisheries‐associated ILK research mostly targets small‐scale and artisanal fishers (70% of studies) and typically uses semi‐structured interviews (60%). We revealed large variability in sample size ( n = 4–7638), predicted by the approach employed and the data generated (i.e. qualitative studies target smaller groups). Using thematic categorisation, we show that scientists are still exploring techniques, or ‘validating’ ILK through comparisons with quantitative scientific data (20%), and recording qualitative information of what fishers understand (40%). A few researchers are applying quantitative social science methods to derive trends in abundance, catch and effort. Such approaches facilitate recognition of local insight in fisheries management but fall short of accepting ILK as a valid complementary way of knowing about fisheries systems. This synthesis reveals that development and increased opportunities are needed to bridge ILK and quantitative scientific data.
Societal Impact Statement Seagrass ecosystems are of fundamental importance to our planet and wellbeing. Seagrasses are marine flowering plants, which engineer ecosystems that provide a multitude of ecosystem services, for example, blue foods and carbon sequestration. Seagrass ecosystems have largely been degraded across much of their global range. There is now increasing interest in the conservation and restoration of these systems, particularly in the context of the climate emergency and the biodiversity crisis. The collation of 100 questions from experts across Europe could, if answered, improve our ability to conserve and restore these systems by facilitating a fundamental shift in the success of such work. Summary Seagrass meadows provide numerous ecosystem services including biodiversity, coastal protection, and carbon sequestration. In Europe, seagrasses can be found in shallow sheltered waters along coastlines, in estuaries & lagoons, and around islands, but their distribution has declined. Factors such as poor water quality, coastal modification, mechanical damage, overfishing, land‐sea interactions, climate change and disease have reduced the coverage of Europe’s seagrasses necessitating their recovery. Research, monitoring and conservation efforts on seagrass ecosystems in Europe are mostly uncoordinated and biased towards certain species and regions, resulting in inadequate delivery of critical information for their management. Here, we aim to identify the 100 priority questions, that if addressed would strongly advance seagrass monitoring, research and conservation in Europe. Using a Delphi method, researchers, practitioners, and policymakers with seagrass experience from across Europe and with diverse seagrass expertise participated in the process that involved the formulation of research questions, a voting process and an online workshop to identify the final list of the 100 questions. The final list of questions covers areas across nine themes: Biodiversity & Ecology; Ecosystem services; Blue carbon; Fishery support; Drivers, Threats, Resilience & Response; Monitoring & Assessment; Conservation & Restoration; Governance, Policy & Management; and Communication. Answering these questions will fill current knowledge gaps and place European seagrass onto a positive trajectory of recovery.
Overcoming ecological feedbacks is a major limiting factor reducing the success of many seagrass restoration projects. Negative feedbacks occur when biotic or abiotic conditions of a site are changed sufficiently after the loss of seagrass to prevent its recovery, even after the original stressors are remediated. While negative feedbacks in seagrass restoration are common, there remain limited studies of ways to reduce them and kick‐start the necessary positive feedbacks to promote recovery. We used field and laboratory experiments to investigate key ecological feedbacks in seagrass ( Zostera marina ) restoration by testing the role of hessian bags and seed burial in reducing seed predation and promoting plant development. We used a double‐hurdle model approach to predict “seagrass emergence success” and “seagrass growth success” across planted field plots. We found that planting seeds in hessian bags and burying them in the sediment improved the likelihood of seeds developing into mature plants. We recorded an average 13‐fold increase in shoot density for seeds planted in buried bags relative to raked furrows. This could be the combined result of reduced predation as well as bags mimicking emergent traits of mature seagrass to withstand physical impacts. We supplement these findings with laboratory evidence that hessian bags provide protection from predation by green shore crabs. Overall, we found a low and variable success rate for seed‐based restoration and indicate other feedbacks in the system beyond those we controlled. However, we show that small methodological changes can help overcome some key feedbacks and improve restoration success.
The areal extent of seagrass meadows is in rapid global decline, yet they provide highly valuable societal benefits. However, their conservation is hindered by data gaps on current and historic spatial extents. Here, we outline an approach for national-scale seagrass mapping and monitoring using an open-source platform (Google Earth Engine) and freely available satellite data (Landsat, Sentinel-2) that can be readily applied in other countries globally. Specifically, we map contemporary (2021) and historical (2000–2021; n = 10 maps) shallow water seagrass extent across the Maldives. We found contemporary Maldivian seagrass extent was ~ 105 km2 (overall accuracy = 82.04%) and, notably, that seagrass area increased threefold between 2000 and 2021 (linear model, + 4.6 km2 year−1, r2 = 0.93, p < 0.001). There was a strongly significant association between seagrass and anthropogenic activity (p < 0.001) that we hypothesize to be driven by nutrient loading and/or altered sediment dynamics (from large scale land reclamation), which would represent a beneficial anthropogenic influence on Maldivian seagrass meadows. National-scale tropical seagrass expansion is unique against the backdrop of global seagrass decline and we therefore highlight the Maldives as a rare global seagrass ‘bright spot’ highly worthy of increased attention across scientific, commercial, and conservation policy contexts.
There is increasing interest in the role that seagrasses play in storing carbon in the context of climate mitigation, but many knowledge gaps in the factors controlling this storage exist. Here, we provide a small case study that examines the role of infaunal biodiversity in influencing seagrass and the carbon stored in its sediments. A total of 25 species of invertebrate were recorded in an intertidal Zostera marina meadow, where these species were dominated by polychaete worms with no bivalves present. We find organic carbon storage (within the top 20 cm) measured by AFDW to be highly variable within a small area of seagrass meadow ranging from 2961 gC.m−2 to 11,620 gC.m−2 with an average (±sd) of 64602 ± 3274 gC.m−2. Our analysis indicates that infaunal communities are significantly and negatively correlated with this sediment organic carbon. However, this effect is not as influential as hypothesised, and the relatively small sample size of the present study limits its ability to provide strong causality. Other factors, such as algal abundance, curiously had a potentially stronger influence on the carbon in the upper sediments. The increasing richness of infauna is likely reducing the build-up of organic carbon, reducing its ecosystem service role. We believe this to likely be the result of bioturbation by specific species such as Arenicola marina and Ampharete acutifrons. A change in sediment organic carbon suggests that these species could be key drivers of bioturbator-initiated redox-driven organic matter turnovers, influencing the microbial processes and remobilizing sediment compounds. Bioturbators should be considered as a limitation to Corg storage when managing seagrass Corg stocks; however, bioturbation is a natural process that can be moderated when an ecosystem is less influenced by anthropogenic change. The present study only provides small-scale correlative evidence with a range of surprising results; confirming these results within temperate seagrasses requires examining this process at large spatial scales or with targeted experiments.
Societal Impact Statement Seagrass meadows are a globally important habitat subject to significant loss. As efforts to restore these sensitive habitats are hampered by their high cost and low levels of reliability, rigorous guidance is required to improve effectiveness and ensure they are cost‐effective. Here, we define 10 golden rules for how we can undertake seagrass restoration. We do this by considering that for seagrass restoration to be successful, it needs to take place with people and not against people. The framework we present aims to direct efforts for seagrass restoration that are holistic and achieve broad goals for people, biodiversity and the planet. Summary The world has lost a significant proportion of its seagrass, and although glimmers of hope for its recovery exist, losses and degradations continue. First and foremost, evidence highlights the need to put the world on a global pathway to seagrass net gain. Achieving this outcome requires that conservation of what remains is a priority, but reaching net gain requires seagrass coverage to increase at rates unlikely to be achieved naturally; large‐scale active restoration is required to fill this gap. Novel finance mechanisms aligned to the climate emergency and biodiversity crises are increasingly leading to larger scale restoration projects. However, no clear framework exists for developing or prioritising approaches. With seagrass restoration expensive and unreliable, rigorous guidance is required to improve effectiveness and ensure it is cost‐effective. Building on evidence from terrestrial and marine sources, here, we apply the ‘10 golden rules’ concept, first outlined for reforestation and later applied to coral reefs, to seagrass restoration. In doing so, we follow international standards for ecological restoration and view seagrass restoration in a broad context, whereby regeneration can be achieved either by planting or by enhancing and facilitating natural recovery. These rules somewhat differ from those on reforestation and coral reef restoration, principally due to the relative immaturity of seagrass restoration science. These 10 golden rules for seagrass restoration are placed within a coupled social‐ecological systems context, and we present a framework for conservation more broadly, to achieve multiple goals pertaining to people, biodiversity and the planet.
Topographic heterogeneity sets the stage for community assembly, but its effects on ecosystem functioning remain poorly understood. Here, we test the hypothesis that topographic heterogeneity underpins multiple cascading species interactions and functional pathways that indirectly control multifunctionality. To do so, we combined experimental manipulation of a form of topographic heterogeneity on rocky shores (holes of various sizes) with a comprehensive assessment of naturally assembled communities and multifunctionality. Structural equation modeling indicated that heterogeneity: (1) enhanced biodiversity by supporting filter feeder richness; (2) triggered a facilitation cascade via reef-forming (polychaete) and biomass-dominant (macroalga) foundation species, which in turn broadly supported functionally diverse epibiotic and understory assemblages; and (3) inhibited a key consumer (limpet). The model supported that these mechanisms exerted complementary positive effects on individual functions (e.g., water filtration, ecosystem metabolism, nutrient uptake) and, in turn, collectively enhanced multifunctionality. Topographic heterogeneity may therefore serve as a cornerstone physical attribute by initiating multiple cascades that propagate through ecological communities via foundation species, ultimately manifesting disproportionate effects on ecosystem multifunctionality.
Leisure boating is becoming more popular in developed societies, stressing seagrass systems. Spatial management and marine zoning, along with education, enforcement, and appropriate signage can reduce this stress. Yet, achieving conservation goals with marine zoning depends on social and organizational factors. Coproduction models that work collaboratively with stakeholders in marine zone or protected area (MPA) planning can improve conservation outcomes. The Florida Keys National Marine Sanctuary (FKNMS; U.S.) encompasses one of the largest seagrass meadows in the world, with the mission to balance marine use with conservation of natural resources. Over the last twelve years, FKNMS has experienced exponential increases in leisure boating, which is having important consequences to the functioning of its managed coastal ecosystems. Following a decade-long planning process, in 2022 FKNMS released a revised draft management plan that uses marine zoning to increase the resilience of FKNMS natural resources by reducing local stresses on the system. In the decade leading to the release of this management plan, for-hire coastal fishers worked with scientists to coproduce comprehensive marine zoning recommendations to reduce leisure boating stresses to seagrass habitats that support important fisheries. Coproduced zoning recommendations would protect 100% and 60% more seagrass and living bottom compared to the FKNMS plan. These recommendations would create an MPA network protecting two seagrass meadows that are centers of activity for important fishery species that form spawning aggregations within a seasonal no fishing MPA. This example highlights how long-term investment in coproduction can result in more comprehensive management plans supported by stakeholders.
Habitat restoration is becoming an increasingly prevalent tool in the armoury of marine conservation, particularly given the expanding interest in creating nature-based solutions to a changing climate. Seagrass restoration is a particular focus of increased numbers of projects and although there is a growing number of examples of successful seagrass restoration attempts, there remain extensive case studies of poor success or restoration failure from around the globe. To enable marine habitat restoration to happen at scale and make a genuine contribution to carbon sequestration rates globally, improved methods that are both practical and simple are required to foster higher rates of success and lower costs. Here, we present seven bottlenecks to achieving reliable seed-based seagrass restoration. In doing so, we also provide opportunities for practical and simple ways in which the knowledge gaps that underpin these bottlenecks can be filled. Seed collection needs to be easier and more efficient; the processing and storage of seeds more controlled; and germination and seedling survival more effective so that fewer seeds are required for more reliable planting. We conclude that further collaborative multidisciplinary science is required in all parts of the world to improve seagrass seed-based restoration through better incorporation of faunal and microbial ecology, more reliable modelling, improved reporting of restoration failures and a wider investigation of seed-based ecology beyond a handful of species.
Habitat suitability modelling (HSM) is a tool that is increasingly being used to help guide decision making for conservation management. It can also be used to focus efforts of restoration in our oceans. To improve on model performance, the best available environmental data along with species distribution data are needed. Marine habitats tend to have ecological niches defined by physical environmental conditions and of particular importance for shallow water species is wave energy. In this study we examined the relative improvements to HSM outputs that could be achieved by producing high-resolution Delft-3D modelled wave height data to see if model predictions at a fine-scale can be improved. Seagrasses were used as an exemplar and comparisons at fine-scale showed considerable differences in the area predicted suitable for seagrass growth and greatly increased the importance of waves as a predictor variable when compared with open-source low resolution wave energy data.
Currents are unique drivers of oceanic phylogeography and thus determine the distribution of marine coastal species, along with past glaciations and sea-level changes. Here we reconstruct the worldwide colonization history of eelgrass (Zostera marina L.), the most widely distributed marine flowering plant or seagrass from its origin in the Northwest Pacific, based on nuclear and chloroplast genomes. We identified two divergent Pacific clades with evidence for admixture along the East Pacific coast. Two west-to-east (trans-Pacific) colonization events support the key role of the North Pacific Current. Time-calibrated nuclear and chloroplast phylogenies yielded concordant estimates of the arrival of Z. marina in the Atlantic through the Canadian Arctic, suggesting that eelgrass-based ecosystems, hotspots of biodiversity and carbon sequestration, have only been present there for ~243 ky (thousand years). Mediterranean populations were founded ~44 kya, while extant distributions along western and eastern Atlantic shores were founded at the end of the Last Glacial Maximum (~19 kya), with at least one major refuge being the North Carolina region. The recent colonization and five- to sevenfold lower genomic diversity of the Atlantic compared to the Pacific populations raises concern and opportunity about how Atlantic eelgrass might respond to rapidly warming coastal oceans.
Distribution of Earth's biomes is structured by the match between climate and plant traits, which in turn shape associated communities and ecosystem processes and services. However, that climate-trait match can be disrupted by historical events, with lasting ecosystem impacts. As Earth's environment changes faster than at any time in human history, critical questions are whether and how organismal traits and ecosystems can adjust to altered conditions. We quantified the relative importance of current environmental forcing versus evolutionary history in shaping the growth form (stature and biomass) and associated community of eelgrass (<i>Zostera marina</i>), a widespread foundation plant of marine ecosystems along Northern Hemisphere coastlines, which experienced major shifts in distribution and genetic composition during the Pleistocene. We found that eelgrass stature and biomass retain a legacy of the Pleistocene colonization of the Atlantic from the ancestral Pacific range and of more recent within-basin bottlenecks and genetic differentiation. This evolutionary legacy in turn influences the biomass of associated algae and invertebrates that fuel coastal food webs, with effects comparable to or stronger than effects of current environmental forcing. Such historical lags in phenotypic acclimatization may constrain ecosystem adjustments to rapid anthropogenic climate change, thus altering predictions about the future functioning of ecosystems.
Seagrass meadows provide a range of key ecosystem services that are of high economic and societal value; seagrass meadows enhance biodiversity, provide food security through fisheries support, and are increasingly recognised for the role they play in mitigating climate change by the process of carbon sequestration. Whilst there is an increasing understanding of the global significance of seagrass habitats, the extent of these habitats is declining globally. The requirement to implement effective seagrass conservation and management strategies is thus becoming increasingly important. If the ambitions of the United Nations 2030 Agenda for Sustainable Development and the Sustainable Development Goals are to be achieved, then nations need ambitious and applicable marine conservation plans. This includes management and protection to vulnerable ecosystems such as seagrass meadows. This study aims to evaluate a range of seagrass management and conservation approaches identified in different geographic regions, using a critique framework developed from the United Nations Environment Programme 2020 report on seagrass “Out Of The Blue: The Value Of Seagrasses To The Environment And To People’. Using the framework, seagrass management in Scotland is used as a case study and compared nationally to the rest of the UK (England, Wales and Northern Ireland) and internationally, to Europe (Wadden Sea), Australia (Great Barrier Reef Marine Park) and West Africa (Senegal). The results identify potential areas of development in Scotland to enhance its seagrass conservation effort, including increased research in seagrass science, widespread mapping of seagrass, long-term monitoring programmes, improved marine protected areas, inclusion of seagrass protective measures into environmental laws and policies and the implementation of appropriate habitat restoration schemes. The results also identify the need for open data if effective knowledge sharing is to take place, and to ensure that ocean science can fully support countries to achieve the 2030 Agenda for Sustainable Development.
Seagrass meadows, like other tropical coastal ecosystems, are highly productive and sustain millions of people worldwide. However, the factors that govern the use of seagrass as a fishing habitat over other habitats are largely unknown, especially at the household scale. Using socioeconomic factors from 147 villages across four countries within the Indo-Pacific, we examined the drivers of household dependence on seagrass. We revealed that seagrass was the most common habitat used for fishing across villages in all the countries studied, being preferred over other habitats for reliability. Using structural equation modelling, we exposed how household income and adaptive capacity appears to govern dependence on seagrass. Poorer households were less likely to own motorboats and dependent on seagrass as they were unable to fish elsewhere, whereas wealthier households were more likely to invest in certain fishing gears that incentivised them to use seagrass habitats due to high rewards and low effort requirements. Our findings accentuate the complexity of seagrass social-ecological systems and the need for empirical household scale data for effective management. Safeguarding seagrass is vital to ensure that vulnerable households have equitable and equal access to the resource, addressing ocean recovery and ensuring sustainable coastal communities.
Seagrass meadows commonly reside in shallow sheltered coastal environments which are typically safe havens for mooring boats. There is evidence from around the globe that the use of common swinging chain moorings leads to halos of bare sediment in otherwise productive seagrass. These halos reduce animal abundance and diversity and lead to a loss of the carbon stored within sediments. To protect and enhance seagrass ecosystem services, low-cost simple solutions are required that can solve the problems of boating-based disturbance. In the present novel study, we provide evidence that the simple replacement of mooring chains with rope can significantly reduce damage to sensitive benthic habitats such as seagrass. At three locations across a range of environmental conditions, we provide evidence that well-established moorings constructed from rope do not damage seagrass. Overall, there was a significant effect (F1,756 = 299.46, p < 0.001) of the mooring type and distance from the mooring base. This equates to a 44% increase in seagrass cover within areas around a rope mooring relative to a chain one. Most small boat mooring activity happens within the summer months, therefore large heavy-duty winter mooring systems are not required in many situations, opening opportunities for adapted systems that have a reduced environmental impact. The present study suggests that there is a ready-made, low-technology, low-cost solution already in existence for halting the widespread loss of seagrass from small boat mooring damage and allowing recovery and opportunity for restoration.
It is widely recognized that humanity is currently facing multiple planetary crises, including the widespread loss of biodiversity and a rapidly changing climate. The impacts of these crises are often far reaching and threaten food security (SDG goal two: zero hunger). Small-scale fisheries are estimated to provide livelihoods for over one hundred million people and sustenance for approximately one billion people but face a plethora of threats and challenges linked to planetary crises. In this multi-country assessment (150 coastal villages across five countries within the Indo-Pacific), household interviews revealed how seagrass meadows are important to small-scale fisheries, particularly as a place to find and collect a reliable source of food. Interviews also revealed that habitat loss and the over-exploitation of these resources are placing people and their food security at risk. This study exposed how dynamic local ecological knowledge can be, uncovering personal opinions and responsibilities that result in the hybridization of knowledge. Here, we demonstrate the importance of using local ecological knowledge to incorporate shared values into management but also highlight that an integrated approach, pairing local and conventional scientific knowledge, is needed urgently if we are to meet the needs of people while simultaneously conserving biodiversity.
To maximize the opportunities of seagrass as a nature-based solution requires restoration to occur on a large scale. New methods and knowledge are required that can solve ecological bottlenecks, improving its reliability and effectiveness. Although there is increasing interest in the use of seeds for seagrass restoration there exists a limited understanding of how best to plant them with the most knowledge on germination and seedling emergence coming from laboratory studies. Here we present the results of a novel field study on the emergence success of seeds of the seagrass <i>Zostera marina</i> when subjected to varied planting treatments. Seeds were planted into hessian bags according to a factorial design of three treatments (sediment type, detritus addition, and nutrient addition). By adding nutrients to natural sediment, the present study provides some evidence of seagrass shoot emergence and maximum shoot length doubling. The present study provides evidence that even in heavily nutrient-rich environments, seagrass sediments may require additional nutrients to improve seedling emergence and growth. It also highlights the highly variable nature of planting seagrass seeds in shallow coastal environments. Critically this study provides increasing levels of evidence that small subtleties in the method can have large consequences for seagrass restoration and that for restoration to scale to levels that are relevant for nature-based solutions there remain many unknowns that require consideration.
While considerable evidence exists of biogeographic patterns in the intensity of species interactions, the influence of these patterns on variation in community structure is less clear. Studying how the distributions of traits in communities vary along global gradients can inform how variation in interactions and other factors contribute to the process of community assembly. Using a model selection approach on measures of trait dispersion in crustaceans associated with eelgrass (<i>Zostera marina</i>) spanning 30° of latitude in two oceans, we found that dispersion strongly increased with increasing predation and decreasing latitude. Ocean and epiphyte load appeared as secondary predictors; Pacific communities were more overdispersed while Atlantic communities were more clustered, and increasing epiphytes were associated with increased clustering. By examining how species interactions and environmental filters influence community structure across biogeographic regions, we demonstrate how both latitudinal variation in species interactions and historical contingency shape these responses. Community trait distributions have implications for ecosystem stability and functioning, and integrating large-scale observations of environmental filters, species interactions and traits can help us predict how communities may respond to environmental change.
Seagrasses are remarkable plants that have adapted to live in a marine environment. They form extensive meadows found globally that bioengineer their local environments and preserve the coastal seascape. With the increasing realization of the planetary emergency that we face, there is growing interest in using seagrasses as a nature-based solution for greenhouse gas mitigation. However, seagrass sensitivity to stressors is acute, and in many places, the risk of loss and degradation persists. If the ecological state of seagrasses remains compromised, then their ability to contribute to nature-based solutions for the climate emergency and biodiversity crisis remains in doubt. We examine the major ecological role that seagrasses play and how rethinking their conservation is critical to understanding their part in fighting our planetary emergency.
Coastal ecosystems, including coral reefs, mangroves, and seagrass, are in global decline. Mitigation approaches include restoration and other managed recovery interventions. To maximise success, these should be guided by an understanding of the environmental niche and geographic limits of foundational species. However, the choices of data, variables, and modelling approaches can be bewildering when embarking on such an exercise, and the biases associated with such choices are often unknown. We reviewed the current available knowledge on methodological approaches and environmental variables used to model and map habitat suitability for coastal ecosystems. While our focus is on seagrass, we draw on information from all marine macrophyte studies for greater coverage of approaches at different scales around the world. We collated 75 publications, of which 35 included seagrasses. Out of all the publications, we found the most commonly used predictor variables were temperature (64%), bathymetry (61%), light availability (49%), and salinity (49%), respectively. The same predictor variables were also commonly used in the 35 seagrass Habitat Suitability Models (HSM) but in the following order: bathymetry (74%), salinity (57%), light availability (51%), and temperature (51%). The most popular method used in marine macrophyte HSMs was an ensemble of models (29%) followed by MaxEnt (17%). Cross-validation was the most commonly used selection procedure (24%), and threshold probability was the favoured model validation (33%). Most studies (87%) did not calculate or report uncertainty measures. The approach used to create an HSM was found to vary by location and scale of the study. Based upon previous studies, it can be suggested that the best approach for seagrass HSM would be to use an ensemble of models, including MaxEnt along with a selection procedure (Cross-validation) and threshold probability to validate the model with the use of uncertainty measures in the model process.
Conserving biodiversity with a growing human population is a key sustainability challenge. Consequently, a vast number of development initiatives across the globe have been designed to combine social, economic, and environmental perspectives. For the most part, the development community is well acquainted with the negative experiences and unintended consequences that some projects have or may bring. However, in tropical coastal ecosystems, this aspect is not completely acknowledged, studied, or understood. Here, we use tropical seagrass meadows as a model social-ecological system to investigate how sustainable development initiatives result in unintended consequences with both positive and negative outcomes for environment and society. We analyze the initiatives and their effects in terms of a typology encompassing “flow”, “addition”, and “deletion” effects and investigate them across four types of sustainable development initiatives that occur within tropical coastal environments: (1) megafauna conservation, (2) alternative livelihood programs, (3) mosquito net malaria prophylaxis, and (4) marine protected areas. Using these four initiatives as examples, we show that sustainable development initiatives can produce unintended effects with major consequences. Further, we illustrate how not assessing such effects may ultimately undermine the initial goals of the sustainable development intervention. Our study suggests that acknowledging unintended effects and transitioning them so that they become sustainable is more effective than ignoring effects or viewing them as trade-offs. We strongly stress the need for an a priori process in which positive effects, negative effects, and potential uncertainties and surprises are considered when planning the development intervention, and we argue for greater social-ecological monitoring of initiatives. As such, this contribution links to contemporary approaches dealing with the sustainability of natural resources and social-ecological systems and bridges with the importance of development initiatives in the context of the United Nations Sustainable Development Goals.
Assessment and monitoring of marine biodiversity, including fish populations, is essential for evidence-based conservation management of coastal marine resources. The effectiveness of monitoring techniques for stock assessment varies with sea conditions. In dynamic marine environments with high turbidity, such as those found in estuaries, mangroves, coastal straits, fjords, and bays, traditional assessment methods include the use of destructive techniques such as trawling. Hydroacoustic sampling techniques overcome such restrictions, equipment such as echosounders have commonly been used for biodiversity assessments including fish community structure, biomass, behaviour, and dynamics studies. However, hydroacoustic methods have been shown to be less reliable for species identification. The high frequency Adaptive Resolution Imaging Sonar (ARIS) is widely used for underwater object detection and imaging. Our study investigated the suitability of ARIS 3000 for the species identification of North-East Atlantic marine species using experimental aquarium studies, field surveys and multi investigator assessments. Aquaria results showed that 82 % of species were detected by observers, of which five were identified correctly identified consistently. The remaining four species were identified correctly <67 % of the time. During field surveys, a 150 % higher confidence in identification was given to more morphologically distinct groups such as elasmobranchs. Whilst our results highlight the suitability of the ARIS for accurate and repeatable identification of some of the model species used in this study, we have also shown that factors such as size and morphological traits limit the accuracy of identification for all species. We suggest that monitoring techniques combine the use of ARIS sonars alongside other sampling tools for assessing motile faunal communities.
Seagrass meadows are threatened by multiple pressures, jeopardizing the many benefits they provide to humanity and biodiversity, including climate regulation and food provision through fisheries production. Conservation of seagrass requires identification of the main pressures contributing to loss and the regions most at risk of ongoing loss. Here, we model trajectories of seagrass change at the global scale and show they are related to multiple anthropogenic pressures but that trajectories vary widely with seagrass life-history strategies. Rapidly declining trajectories of seagrass meadow extent (>25% loss from 2000 to 2010) were most strongly associated with high pressures from destructive demersal fishing and poor water quality. Conversely, seagrass meadow extent was more likely to be increasing when these two pressures were low. Meadows dominated by seagrasses with persistent life-history strategies tended to have slowly changing or stable trajectories, while those with opportunistic species were more variable, with a higher probability of either rapidly declining or rapidly increasing. Global predictions of regions most at risk for decline show high-risk areas in Europe, North America, Japan, and southeast Asia, including places where comprehensive long-term monitoring data are lacking. Our results highlight where seagrass loss may be occurring unnoticed and where urgent conservation interventions are required to reverse loss and sustain their essential services.
Fishing activities conducted on seagrass bed to capture fishes and other seagrass associated fauna are very massive especially in the Pacific regions and undeveloped countries. This is due to the high abundance of economically important species associated to seagrasses, and additionally, seagrass area is the most accessible fishing ground throughout the year and with low capital. Seagrass meadows are importance habitat to support an abundance and diverse fish assemblages that form the basis for artisanal fisheries, which are vital in maintaining food security of coastal community in the regions. The seagrass fishery is considered a small-scale, multi-species and multi-gear fisheries. One of the fishing gear used in this fishery is traditional permanent fish trap called “sero”. Bycatch from some small-scale fisheries have been reported such as from trawls, traps, gill nets, and longline fisheries. This study aimed to identify bycatch species from “sero”, a type of seagrass fisheries which is in the form of fish fences with nets positioned on intertidal area of seagrass bed to the subtidal for approximately 200m. The result shown the bycatch from this fisheries was dominated by either low value fishes or invaluable and even toxic fishes for consumption, such as the puffers (Tetraodontidae and Diodontidae), juveniles of Apogonidae and Chaetodontidae. Additionally, sharks, turtles, and rays were also found in the bycatch. This result should be put into consideration as the bycatch would have an ecological consequences on the population, predator-prey relationship, and ecosystem resilience to stressor in general. Information from this study will be important for sustainable small-scale fisheries management and seagrass conservation, and therefore, further research into bycatch reduction in this fishery would be desirable.
A growing body of research is documenting the accumulation of microplastics within marine sediments around the world. The hydrodynamic influences of seagrasses in coastal environments are shown to increase sedimentation of finer particles and as a result there has been speculation that this attribute will lead to seagrass meadows acting as a site of elevated microplastic contamination. To date a range of localised studies have provided conflicting answers to this hypothesis. Seagrass meadows provide multiple ecosystem services including vital support roles for a range of fisheries; therefore, there are considerable human health implications for understanding their role as sinks of microplastics. This research investigated the abundance and diversity of microplastics present in temperate North Atlantic seagrass meadow sediments relative to unvegetated sediments and examined how they correlate with the meadow structure and the sediment type. We also placed this data in the context of the current knowledge of microplastics in seagrass sediments through a global meta-analysis of published data. Eight seagrass meadows and adjacent unvegetated sites around the UK were sampled to test for the abundance of microplastic particles in the sediment. Microplastics were found in 98% of the samples, with fibres making up 91.8% of all microplastics identified. Abundance was recorded to overall be 215 ± 163 microplastic particles (MP) kg−1 Dry Weight (DW) of sediment in seagrass and 221 ± 236 MP kg−1 DW of sediment in unvegetated habitats. There were no significant differences found between the number of MP with respect to vegetation. We report evidence of the almost ubiquitous contamination of seagrass sediments with microplastics both in the UK and globally but find that the contamination reflects a general build-up of microplastics in the wider environment rather than becoming concentrated within seagrass as an enhanced sink. Microplastic build up in sediments is hypothesised to be the result of local hydrodynamics and plastic sources rather than the result of elevated habitat level concentration. Although not of a higher abundance in seagrass, such contamination in seagrass is of cause for concern given the high dependency of many species of fish on these habitat types and the potential for plastics to move up the food chain.
Marine ecosystems are in a state of crisis worldwide due to anthropogenic stressors, exacerbated by generally diminished ocean literacy. In other sectors, big data and technological advances are opening our horizons towards improved knowledge and understanding. In the marine environment the opportunities afforded by big data and new technologies are limited by a lack of available empirical data on habitats, species, and their ecology. This limits our ability to manage these systems due to poor understanding of the processes driving loss and recovery. For improved chances of achieving sustainable marine systems, detailed local data is required that can be connected regionally and globally. Citizen Science (CS) is a potential tool for monitoring and conserving marine ecosystems, particularly in the case of shallow nearshore habitats, however, limited understanding exists as to the effectiveness of CS programmes in engaging the general public or their capacity to collect marine big data. This study aims to understand and identify pathways for improved engagement of citizen scientists. We investigated the motivations and barriers to engagement of participants in CS using two major global seagrass CS programmes. Programme participants were primarily researchers in seagrass science or similar fields which speak to a more general problem of exclusivity across CS. Altruistic motivations were demonstrated, whilst deterrence was associated with poor project organisation and a lack of awareness of specified systems and associated CS projects. Knowledge of seagrass ecosystems from existing participants was high and gains because of participation consequently minimal. For marine CS projects to support big data, we need to expand and diversify their current user base. We suggest enhanced outreach to stakeholders using cooperatively identified ecological questions, for example situated within the context of maintaining local ecosystem services. Dissemination of information should be completed with a variety of media types and should stress the potential for knowledge transfer, novel social interactions, and stewardship of local environments. Although our research confirms the potential for CS to foster enhanced collection of big data for improved marine conservation and management, we illustrate the need to improve and expand approaches to user engagement to reach required data targets.
Coastal ecosystems provide vital ecosystem functions and services, but have been rapidly degrading due to human impacts. Restoration is increasingly considered key to reversing these losses, but is often unsuccessful. Recent work on seagrasses and salt marsh cordgrasses highlights that restoration yields can be greatly enhanced by temporarily mimicking key emergent traits. These traits are not expressed by individual seedlings or small clones, but emerge in clumped individuals or large clones to locally suppress environmental stress, causing establishment thresholds where such density-dependent self-facilitation is important for persistence. It remains unclear, however, to what extent the efficacy of restoration via emergent trait-based mimicry depends on the intensity of stressors. We test this in a restoration experiment with the temperate seagrass Zostera marina at four sites (Finland, Sweden, UK, USA) with contrasting hydrodynamic regimes, where we simulated dense roots mats or vegetation canopies with biodegradable structural mimics. Results show that by mimicking sediment-stabilizing root mats, seagrass transplant survival, growth and expansion was strongly enhanced in hydrodynamically exposed environments. However, these positive effects decreased and turned negative under benign conditions, while mimics insufficiently mitigated physical stress in extremely exposed environments, illustrating upper and lower limits of the application. Furthermore, we found that aboveground structures, designed to mimic stiff rather than flexible vegetation canopies, underperformed compared to belowground mimics. Our findings emphasize the importance of understanding the conditions at the restoration site, species-specific growth requirements, and self-facilitating traits that organisms may express when applying emergent trait-mimicry as a tool to improve restoration success.
Baited remote underwater videos (BRUV) are popular marine monitoring techniques used for the assessment of motile fauna. Currently, most published studies evaluating BRUV methods stem from environments in the Southern Hemisphere. This has led to stricter and more defined guidelines for the use of these techniques in these areas in comparison to the North Atlantic, where little or no specific guidance exists. This study explores metadata taken from BRUV deployments collected around the UK to understand the influence of methodological and environmental factors on the information gathered during BRUV deployments including species richness, relative abundance and faunal composition. In total, 39 BRUV surveys accumulating in 457 BRUV deployments across South/South-West England and Wales were used in this analysis. This study identified 88 different taxa from 43 families across the 457 deployments. Whilst taxonomic groups such as Labridae, Gadidae and Gobiidae were represented by a high number of species, species diversity for the Clupeidae, Scombridae, Sparidae, Gasterosteidae and Rajidae groups were low and many families were absent altogether. Bait type was consistently identified as one of the most influential factors over species richness, relative abundance and faunal assemblage composition. Image quality and deployment duration were also identified as significant influential factors over relative abundance. As expected, habitat observed was identified as an influential factor over faunal assemblage composition in addition to its significant interaction with image quality, time of deployment, bait type and tide type (spring/neap). Our findings suggest that methodological and environmental factors should be taken into account when designing and implementing monitoring surveys using BRUV techniques. Standardising factors where possible remains key. Fluctuations and variations in data may be attributed to methodological inconsistencies and/or environment factors as well as over time and therefore must be considered when interpreting the data.
The spatial extent of seagrass is poorly mapped, and knowledge of historical loss is limited. Here, we collated empirical and qualitative data using systematic review methods to provide unique analysis on seagrass occurrence and loss in the United Kingdom. We document 8,493 ha of recently mapped seagrass in the United Kingdom since 1998. This equates to an estimated 0.9 Mt of carbon, which, in the current carbon market represents about £22 million. Using simple models to estimate seagrass declines triangulated against habitat suitability models, we provide evidence of catastrophic seagrass loss; at least 44% of United Kingdom's seagrasses have been lost since 1936, 39% since the 1980's. However, losses over longer time spans may be as high as 92%. Based on these estimates, historical seagrass meadows could have stored 11.5 Mt of carbon and supported approximately 400 million fish. Our results demonstrate the vast scale of losses and highlight the opportunities to restore seagrass to support a range of ecosystems services.
Seagrass ecosystems provide critical contributions (goods and perceived benefits or detriments) for the livelihoods and wellbeing of Pacific Islander peoples. Through in-depth examination of the contributions provided by seagrass ecosystems across the Pacific Island Countries and Territories (PICTs), we find a greater quantity in the Near Oceania (New Guinea, the Bismarck Archipelago and the Solomon Islands) and western Micronesian (Palau and Northern Marianas) regions; indicating a stronger coupling between human society and seagrass ecosystems. We also find many non-material contributions historically have been overlooked and under-appreciated by decision-makers. Closer cultural connections likely motivate guardianship of seagrass ecosystems by Pacific communities to mitigate local anthropogenic pressures. Regional comparisons also shed light on general and specific aspects of the importance of seagrass ecosystems to Pacific Islanders, which are critical for forming evidence-based policy and management to ensure the long-term resilience of seagrass ecosystems and the contributions they provide.
Seagrass ecosystems exist throughout Pacific Island Countries and Territories (PICTs). Despite this area covering nearly 8% of the global ocean, information on seagrass distribution, biogeography, and status remains largely absent from the scientific literature. We confirm 16 seagrass species occur across 17 of the 22 PICTs with the highest number in Melanesia, followed by Micronesia and Polynesia respectively. The greatest diversity of seagrass occurs in Papua New Guinea (13 species), and attenuates eastward across the Pacific to two species in French Polynesia. We conservatively estimate seagrass extent to be 1446.2 km<sup>2</sup>, with the greatest extent (84%) in Melanesia. We find seagrass condition in 65% of PICTs increasing or displaying no discernible trend since records began. Marine conservation across the region overwhelmingly focuses on coral reefs, with seagrass ecosystems marginalised in conservation legislation and policy. Traditional knowledge is playing a greater role in managing local seagrass resources and these approaches are having greater success than contemporary conservation approaches. In a world where the future of seagrass ecosystems is looking progressively dire, the Pacific Islands appears as a global bright spot, where pressures remain relatively low and seagrass more resilient.
Seagrass meadows are known to be rich in fauna, with complex food webs that provide trophic subsidy to species and habitats way beyond the extent of their distribution. Birds are an often-overlooked part of marine ecosystems; not only are they crucial to the health of marine ecosystems, but their populations are also supported by the productivity and biodiversity of marine ecosystems. The links of birds to specific habitat types such as seagrass meadows are largely not considered except in the context of direct herbivorous consumption. Here, we examine the linkages between seagrass and birds and propose a conceptual framework for how seagrasses may support bird populations beyond their distribution in both direct and indirect pathways. We present evidence that seagrass meadows are globally foraged for fish and invertebrates by coastal birds. They are also targeted by herbivorous wildfowl and potentially benefit birds further afield indirectly as a result of their support for offshore marine fish species at critical times in their life cycle (e.g., Atlantic Cod and King George Whiting). Evidence from the literature indicates that seagrass does provide support for birds, but reveals a field of research requiring much gap filling as studies are globally sparse, mechanistically limited, and small in spatial and temporal scales.
Seagrasses – a group of foundation species in coastal ecosystems – provide key habitat for diverse and abundant faunal assemblages and support numerous ecosystem functions and services. However, whether the habitat role of seagrasses is influenced by seagrass diversity, by dominant species or both, remains unclear. To that end, we sought to investigate the specific seagrass characteristics (e.g., species diversity, seagrass traits) that influence tropical fish assemblages, and place this in the context of small-scale fishery use. We surveyed seagrass variables at 55 plots, nested within 12 sites around Zanzibar (Tanzania) in the Western Indian Ocean, and used Baited Remote Underwater Video (BRUV) systems to assess fish assemblages across plots. Using linear mixed models, we reveal that seagrass structural complexity and depth were the best predictors of fish abundance, with higher abundance occurring in deeper meadows or meadows with high canopy, leaf length and number of leaves per shoot. Moreover, an interaction between seagrass cover and land-use was the best predictor of fish species richness, where sites closer to human impacts were less affected by cover than sites with lower human impact. Overall, models with seagrass species richness or functional diversity as predictors poorly explained fish assemblages. Fish taxa that were important for small-scale fishery sectors (e.g., emperors, snappers, rabbitfish, and parrotfish) were primarily driven by seagrass structural complexity. Our results provide a unique analysis of the relationship between seagrass habitat and its associated fish assemblages in that we show that seagrass species diversity had little effect on seagrass fish assemblages, which instead appear driven by specific seagrass traits and seagrass cover. If conserving high value species that support adjacent fisheries is the priority for protecting seagrass meadows, then seagrass areas should be chosen with high cover and structural complexity that are in deeper waters. Any conservation measures also need to balance the needs of fishers that use the resources supported by seagrasses.
The phenotypic plasticity of seagrasses enables them to adapt to changes in environmental conditions and withstand or recover from disturbance. This plasticity was demonstrated in the large variation recorded throughout a suite of bioindicators measured within <i>Zostera marina</i> meadows around Wales and SW England, United Kingdom. Short-term spatial data were analysed alongside long-term monitoring data to determine which bioindicators best described the status of eelgrass meadows subjected to a range of environmental and anthropogenic drivers. Shoot density, leaf length, leaf nutrients (C:N ratio, %N, %P) including stable isotope of δ<sup>13</sup>C and δ<sup>15</sup>N provided insight into the longer-term status of the meadows studied and a good indication of the causes of long-term decline. Meadows ranged from those in the Isles of Scilly with little evidence of impact to those in Littlewick in Milford Haven, Wales that showed the highest levels of impacts of all sites. Bioindicators at Littlewick showed clear warning signs of nutrient loading reflected in the long-term decline in shoot density, and prevalence of wasting disease. This study highlights the need for continuous consistent monitoring and the benefits of using extra tools in the form of shoot nutrient analysis to determine causes of decline.
To better understand dietary requirements, trophic shifts, and trophic interactions of the threatened green turtle (Chelonia mydas), we conducted a comprehensive global review and literature tabulation (177 studies) reporting diets of individuals > 25 cm carapace length. We analysed those studies involving natural sites and healthy animals that reported relative proportions of all diet components (67 studies, 89 datasets at 75 sites, 13 geographic sub-regions, 3 oceans). We compared diets by sub-region and foraging site relative to four diet components, i.e., seagrass, macroalgae, terrestrial plants (including mangroves) and animal matter. To assess sea surface temperature (SST) as an environmental driver, values were extracted from satellite data (single year) and site-specific observations (study durations) and examined relative to diet composition. Satellite data indicated that at warmer sites with temperatures > 25 °C (≥ 6 months annually), diet was predominantly herbivorous (mean = 92.97%; SE = 9.85; n = 69 datasets). At higher latitude sites and in cold-water currents with SST < 20 °C (≥ 6 months annually), dietary animal matter featured prominently (mean = 51.47%; SE = 4.84; n = 20 datasets). Site-specific observations indicated that SST had a small but significant effect on contributions of animal matter (r2 = 0.17, P = < 0.001) and seagrass (r2 = 0.24, P = < 0.001) but not macroalgae and terrestrial plants. Our study presents the first quantitative evidence at a global scale that temperature may be an important driver of omnivory, providing a new perspective on variations in green turtle diet, especially in light of global warming and climate change.
The development and uptake of citizen science and artificial intelligence (AI) techniques for ecological monitoring is increasing rapidly. Citizen science and AI allow scientists to create and process larger volumes of data than possible with conventional methods. However, managers of large ecological monitoring projects have little guidance on whether citizen science, AI, or both, best suit their resource capacity and objectives. To highlight the benefits of integrating the two techniques and guide future implementation by managers, we explore the opportunities, challenges, and complementarities of using citizen science and AI for ecological monitoring. We identify project attributes to consider when implementing these techniques and suggest that financial resources, engagement, participant training, technical expertise, and subject charisma and identification are important project considerations. Ultimately, we highlight that integration can supercharge outcomes for ecological monitoring, enhancing cost-efficiency, accuracy, and multi-sector engagement.
The global distribution of primary production and consumption by humans (fisheries) is well-documented, but we have no map linking the central ecological process of consumption within food webs to temperature and other ecological drivers. Using standardized assays that span 105° of latitude on four continents, we show that rates of bait consumption by generalist predators in shallow marine ecosystems are tightly linked to both temperature and the composition of consumer assemblages. Unexpectedly, rates of consumption peaked at midlatitudes (25 to 35°) in both Northern and Southern Hemispheres across both seagrass and unvegetated sediment habitats. This pattern contrasts with terrestrial systems, where biotic interactions reportedly weaken away from the equator, but it parallels an emerging pattern of a subtropical peak in marine biodiversity. The higher consumption at midlatitudes was closely related to the type of consumers present, which explained rates of consumption better than consumer density, biomass, species diversity, or habitat. Indeed, the apparent effect of temperature on consumption was mostly driven by temperature-associated turnover in consumer community composition. Our findings reinforce the key influence of climate warming on altered species composition and highlight its implications for the functioning of Earth's ecosystems.
Global fisheries are in decline, calling for urgent evidence-based action. One such action is the identification and protection of fishery-associated habitats such as seagrass meadows and kelp forests, both of which have suffered long-term loss and degradation in the North Atlantic region. Direct comparisons of the value of seagrass and kelp in supporting demersal fish assemblages are largely absent from the literature. Here, we address this knowledge gap. Demersal fish were sampled using a baited camera to test for differences between habitats in (1) the species composition of the fish assemblages, (2) the total abundance and species richness of fishes, and (3) the abundances of major commercial species. Seagrass and kelp-associated fish assemblages formed two significantly distinct groupings, which were driven by increased whiting (Merlangius merlangus) and dogfish (Scyliorhinus canicula) presence in seagrass and higher abundances of pollock (Pollachius pollachius) and goby (Gobiusculus flavescens) in kelp. The abundance, diversity, and species richness did not change significantly between the two habitats. We conclude that seagrass and kelp do support unique demersal fish assemblages, providing evidence that they have different ecological value through their differing support of commercial fish species. Thus, this study improves the foundation for evidence-based policy changes.
Abstract Biodiversity in turbid aquatic environments is commonly assessed using extractive sampling methods that damage the seabed. Underwater cameras equipped with clear liquid optical chambers (CLOCs) for the assessment of seabed habitats and species are a non‐extractive alternative and have been applied in turbid environments globally. A CLOC is a body of clear liquid positioned in front of a camera to reduce the scattering of light that would otherwise occur when passing through the turbid water it displaces. Here, we test and quantify the effectiveness of a CLOC for marine benthic biodiversity assessments over gradients of increasing turbidity. The addition of a CLOC to a conventional benthic camera system significantly enhanced the quality of information gathered. Images acquired using the CLOC system consistently recorded statistically higher values of image quality (49% increase, based on the clarity of the image), seabed visible within the drop‐down frame (34% increase), and European Nature Information System habitat level identification (49% increase). Furthermore, it was found that the ‘annotation success’ of taxa (classification of a specimen to family level or higher) was found to increase between individual experts in the presence of a CLOC. A reduced sampling effort was also identified when using a CLOC. Taxonomic richness increased by 27% when comparing the same number of image stills collected with and without the CLOC. By reducing the limitations of underwater visibility previously attributed to underwater cameras, this concept extends the potential for use of non‐destructive survey techniques and allows for future users to collect robust information of an area, making better informed management decisions.
Restoration is becoming a vital tool to counteract coastal ecosystem degradation. Modifying transplant designs of habitat-forming organisms from dispersed to clumped can amplify coastal restoration yields as it generates self-facilitation from emergent traits, i.e. traits not expressed by individuals or small clones, but that emerge in clumped individuals or large clones. Here, we advance restoration science by mimicking key emergent traits that locally suppress physical stress using biodegradable establishment structures. Experiments across (sub)tropical and temperate seagrass and salt marsh systems demonstrate greatly enhanced yields when individuals are transplanted within structures mimicking emergent traits that suppress waves or sediment mobility. Specifically, belowground mimics of dense root mats most facilitate seagrasses via sediment stabilization, while mimics of aboveground plant structures most facilitate marsh grasses by reducing stem movement. Mimicking key emergent traits may allow upscaling of restoration in many ecosystems that depend on self-facilitation for persistence, by constraining biological material requirements and implementation costs.
Seagrass meadows globally are under pressure with worldwide loss and degradation, but there is a growing recognition of the global importance of seagrass ecosystem services, particularly as a major carbon sink and as fisheries habitat. Estimates of global seagrass spatial distribution differ greatly throughout the published literature, ranging from 177 000 to 600 000 km2 with models suggesting potential distribution an order of magnitude higher. The requirements of the Paris Climate Agreement by outlining National Determined Contributions (NDCs) to reduce emissions is placing an increased global focus on the spatial extent, loss and restoration of seagrass meadows. Now more than ever there is a need to provide a more accurate and consistent measure of the global spatial distribution of seagrass. There is also a need to be able to assess the global spread of other seagrass ecosystem services and in their extension, the values of these services. In this study, by rationalising and updating a range of existing datasets of seagrass distribution around the globe, we have estimated with Moderate to High confidence the global seagrass area to date as 160 387 km2, but possibly 266 562 km2 with lower confidence. We break this global estimate down to a national level with a detailed analysis of the current state of mapped distribution and estimates of seagrass area per country. Accurate estimates, however, are challenged by large areas remaining unmapped and inconsistent measures being used. Through the examination of current global maps, we are able to propose a pathway forward for improving mapping of this important resource. More accurate measure of global #seagrass distribution, critical for assessing current state and trends
The use of baited remote underwater video (BRUV) for examining and monitoring marine biodiversity in temperate marine environments is rapidly growing, however many aspects of their effectiveness relies on assumptions based on studies from the Southern Hemisphere. The addition of bait to underwater camera systems acts as a stimulus for attracting individuals towards the camera field of view, however knowledge of the effectiveness of different bait types in northern temperate climbs is limited, particularly in dynamic coastal environments. Studies in the Southern Hemisphere indicate that oily baits are most effective whilst bait volume and weight do not impact BRUV effectiveness to any great degree. The present study assesses the influence of four bait types (mackerel, squid, crab and no bait (control)) on the relative abundance, taxonomic diversity and faunal assemblage composition at two independent locations within the North-Eastern Atlantic region; Swansea Bay, UK and Ria Formosa Lagoon, Portugal. Two different bait quantities (50 g and 350 g) were further trialled in Swansea Bay. Overall, patterns showed that baited deployments recorded statistically higher values of relative abundance and taxonomic diversity when compared to un-baited deployments in Swansea Bay but not in Ria Formosa Lagoon. No statistical evidence singled out one bait type as best performing for attracting higher abundances and taxonomic diversity in both locations. Faunal assemblage composition was however found to differ with bait type in Swansea Bay, with mackerel and squid attracting higher abundances of scavenging species compared to the crab and control treatments. With the exception of squid, bait quantity had minimal influence on bait attractiveness. It is recommended for consistency that a minimum of 50 g of cheap, oily fish such as mackerel is used as bait for BRUV deployments in shallow dynamic coastal environments in the North-Eastern Atlantic Region.
Seagrasses are subjected to intense levels of anthropogenic disturbance as a result of the shallow nearshore waters they inhabit. Some seagrasses are known to have dynamic growth patterns, enabling them to colonize unstable shallow environments and adapt to a range of disturbances. This can result in high levels of variability in morphological and physiological attributes. The seagrass Halodule wrightii is known to be a fast-growing pioneering species with a large geographic range. The present study examines Halodule wrightii in a region under intense anthropogenic stress in order to determine what are the main environmental drivers affecting the morphology, physiology and status of these habitats. Parameters of plant morphology, physiology and status were measured either at the meadow scale (e.g. biochemistry) or at a higher frequency shoot scale (e.g. shoot width). We assigned an impact assessment index to a series of seagrass sites over a gradient of anthropogenic disturbance and found this to be explanatory of a number of the seagrass parameters measured including epiphyte cover, stable isotope δ15N and ETRmax however, it did not clearly explain shoot density, a commonly used bioindicator of environmental stress. At the shoot scale, Principal Component Analysis identified epiphyte and leaf width to have the strongest association. At the meadow scale this was shoot density, dry weight and Ek, albeit with the most impacted sites showing highest shoot density. Stable isotope (δ15N) and leaf length were most significant in explaining the variation between sites and impact category, providing a direct link between anthropogenic sources of nutrients to seagrass meadow density.
Gear restrictions are an important management tool in small-scale tropical fisheries, improving sustainability and building resilience to climate change. Yet to identify the management challenges and complete footprint of individual gears, a broader systems approach is required that integrates ecological, economic and social sciences. Here we apply this approach to artisanal fish fences, intensively used across three oceans, to identify a previously underrecognized gear requiring urgent management attention. A longitudinal case study shows increased effort matched with large declines in catch success and corresponding reef fish abundance. We find fish fences to disrupt vital ecological connectivity, exploit > 500 species with high juvenile removal, and directly damage seagrass ecosystems with cascading impacts on connected coral reefs and mangroves. As semi-permanent structures in otherwise open-access fisheries, they create social conflict by assuming unofficial and unregulated property rights, while their unique high-investment-low-effort nature removes traditional economic and social barriers to overfishing.
Green turtles (Chelonia mydas) are key herbivores of tropical and subtropical neritic habitats and play a major role in structuring seagrass meadows. We present the first detailed assessment of green turtle diet in the Western Indian Ocean using the gut contents of salvaged animals from three atolls in the Republic of Seychelles separated from each other by 400–825 km: Cosmoledo (adults, n = 12), Farquhar (adults, n = 33; immature, n = 1) collected in 1982–1983; and Desroches (immatures, n = 8) in 2016–2018. We report the first comparison of the diets of gravid females (n = 17), males (n = 26) and non-breeding females (n = 2) at sites providing both foraging and breeding habitat. Seagrass (mostly Thalassodendron ciliatum) dominated the diet, accounting for 95% of the mean gut content biomass for males and non-breeding females but only 58% for gravid females, alongside relatively large amounts of substrate (14%) and macroalgae (13%). Satellite tracking of post-nesting green turtles from Chagos Archipelago in 2016 located foraging sites at Farquhar Atoll that coincided with capture locations of 26 of the 33 adult turtles sampled there in 1983. In situ surveys of those sites in 2018 revealed extensive nearly monospecific beds of T. ciliatum. The prominence of seagrass in the diet of green turtles and connectivity between foraging and nesting habitats throughout the region illustrate the need to conserve and monitor seagrass habitats of the Western Indian Ocean especially in the context of changing green turtle population densities.
Abstract Current knowledge of turbid coastlines relies heavily on extractive sampling methods with less destructive visual techniques limited primarily by underwater visibility. Baited Remote Underwater Video (BRUV) is now a commonly used nonextractive sampling technique which involves the use of bait to attract motile fauna to the field of view of the camera, but its use is restricted to clear water environments. Here, we describe and test the addition of a clear liquid optical chamber (CLOC) to a BRUV system to improve underwater visibility when observing motile fauna in turbid waters. The CLOC method was trialed with respect to the ability of the system to identify taxa to species level in both controlled laboratory and field conditions across gradients of underwater visibility. This study found that the introduction of a CLOC to a conventional BRUV system significantly improved the ability to observe identifying features of four fish species in a controlled low‐visibility environment ( p ≤ 0.001). The ability to identify taxa to species level in field conditions was also significantly increased with the addition of a CLOC ( p ≤ 0.01). We conclude that the introduction of a CLOC to a conventional BRUV system is a reliable way of improving underwater visibility when assessing motile fauna allowing for a more consistent identification of taxa to species level. This system may be applied to both marine and freshwater aquatic environments.
Seagrasses are marine flowering plants, which form extensive meadows mostly in shallow water marine environments. They provide a wide range of ecosystem services, which can be grouped into four broad categories: provisioning (e.g. food production); regulating (e.g. controlling climate and disease); supporting (e.g. nutrient cycles and oxygenation); and cultural (e.g. spiritual and recreational benefits). These services directly or indirectly benefit humans. Seagrass have contributed to the fulfilment of human needs for a very long time, before the term “ecosystem services” was coined. However, there is a lack of knowledge regarding public awareness on seagrasses and the benefits they provide. In this study, we conducted a workshop in Selayar Archipelago, South Sulawesi, Indonesia, an area with extensive seagrass meadows. The workshop focussed on seagrass meadows in the context of coastal community livelihood-related activities. The 50 workshop participants came from a variety of backgrounds, mostly related to the marine and fisheries sector (e.g. fishermen, vocational high school students, conservation agency staff, district government fisheries officers, and fisheries extension staff). The workshop revealed that many marine and fisheries stakeholders have a high level of awareness regarding seagrasses and the basic ecosystem services they provide. Some key points were identified from the workshop: 1) seagrasses were recognised as a resource; 2) the most and least frequently mentioned ecosystem service types mentioned were “provisioning” and “cultural”, respectively; 3) threats to seagrass meadows were identified and practical recommendations to minimize the threats were formulated.
Invertebrate gleaning (walking) fisheries are common within intertidal seagrass meadows globally, contributing to the food supply of hundreds of millions of people, but understanding of these fisheries and their ecological drivers are extremely limited. The present study provides a unique analysis of these fisheries using a combined social and ecological approach. Catches contained 34 species and were dominated by Bivalves, Urchins and Gastropods. CPUE in all sites varied from 0.05 to 3 kg gleaner−1 hr−1, respectively, with the majority of fishers being women and children. Landings were of major significance for local food supply and livelihoods at all sites. Local ecological knowledge suggests seagrass meadows are declining in line with other regional trends. Increasing seagrass density significantly and positively correlated with CPUE of the invertebrate gleaning (r = 0.830) highlighting the importance of conserving these threatened habitats. Understanding the complexities of these fisheries, their supporting habitats and their sustainability is important for the support of sustainable coastal livelihoods.
Seagrass meadows are an important wetland habitat that have been degraded globally but have an important carbon storage role. In order to expand the restoration of these productive and biodiverse habitats methods are required that can be used for large scale habitat creation across a range of environmental conditions. The spreading of seagrass seeds has been proven to be a successful method for restoring seagrass around the world, however in places where tidal range is large such methods become limited by resultant water movements. Here we describe and test a method for deploying seagrass seeds of the species Zostera marina over large scales using a new, simple method “Bags of Seagrass Seeds Line (BoSSLine).” This method involved planting seeds and sediment using natural fiber hessian bags deployed along strings anchored onto the seabed. When deployed in a suitable environment 94% of bags developed mature seagrass shoots, unfortunately one site subjected to a large storm event resulted in sediment burial of the bags and no seed germination. Bags were filled with 100 seeds with each leading to the development of 2.37 ± 2.41 mature shoots (206 ± 87 mm in length) 10 months after planting. The method was proven successful however the experiments illustrated the need to ensure habitat suitability prior to their use. Low seed success rate was comparable to other restoration studies, however further trials are recommended to ensure ways to improve this rate. In conclusion, this study provides evidence for an effective, simple method “Bags of Seagrass Seeds Line (BoSSLine)” for deploying seeds of the seagrass Zostera marina over large scales.
Malaria is a serious global health issue, with around 200 million cases per year. As such, great effort has been put into the mass distribution of bed nets as a means of prophylaxis within Africa. Distributed mosquito nets are intended to be used for malaria protection, yet increasing evidence suggests that fishing is a primary use for these nets, providing fresh concerns for already stressed coastal ecosystems. While research documents the scale of mosquito net fisheries globally, no quantitative analysis of their landings exists. The effects of these fisheries on the wider ecosystem assemblages have not previously been examined. In this study, we present the first detailed analysis of the sustainability of these fisheries by examining the diversity, age class, trophic structure and magnitude of biomass removal. Dragnet landings, one of two gear types in which mosquito nets can be utilised, were recorded across ten sites in northern Mozambique where the use of Mosquito nets for fishing is common. Our results indicate a substantial removal of juveniles from coastal seagrass meadows, many of which are commercially important in the region or play important ecological roles. We conclude that the use of mosquito nets for fishing may contribute to food insecurity, greater poverty and the loss of ecosystem functioning.
In coastal waters around the world, the dominant primary producers are benthic macrophytes, including seagrasses and macroalgae, that provide habitat structure and food for diverse and abundant biological communities and drive ecosystem processes. Seagrass meadows and macroalgal forests play key roles for coastal societies, contributing to fishery yields, storm protection, biogeochemical cycling and storage, and important cultural values. These socio-economically valuable services are threatened worldwide by human activities, with substantial areas of seagrass and macroalgal forests lost over the last half-century. Tracking the status and trends in marine macrophyte cover and quality is an emerging priority for ocean and coastal management, but doing so has been challenged by limited coordination across the numerous efforts to monitor macrophytes, which vary widely in goals, methodologies, scales, capacity, governance approaches, and data availability. Here, we present a consensus assessment and recommendations on the current state of and opportunities for advancing global marine macrophyte observations, integrating contributions from a community of researchers with broad geographic and disciplinary expertise. With the increasing scale of human impacts, the time is ripe to harmonize marine macrophyte observations by building on existing networks and identifying a core set of common metrics and approaches in sampling design, field measurements, governance, capacity building, and data management. We recommend a tiered observation system, with improvement of remote sensing and remote underwater imaging to expand capacity to capture broad-scale extent at intervals of several years, coordinated with stratified in situ sampling annually to characterize the key variables of cover and taxonomic or functional group composition, and to provide ground-truth. A robust networked system of macrophyte observations will be facilitated by establishing best practices, including standard protocols, documentation, and sharing of resources at all stages of workflow, and secure archiving of open-access data. Because such a network is necessarily distributed, sustaining it depends on close engagement of local stakeholders and focusing on building and long-term maintenance of local capacity, particularly in the developing world. Realizing these recommendations will produce more effective, efficient, and responsive observing, a more accurate global picture of change in vegetated coastal systems, and stronger international capacity for sustaining observations.
Seagrass meadows around the world are under threat and most are in decline, including the extensive meadows along the western coast of Selayar Island, Indonesia. In the 1980s these seagrass meadows were still in good condition, as evidenced by the abundance and variety of gastropods which could be caught at high tide using a push net. This Activity has now stopped and shell collection can only be done during low tide. Around 60% of remaining seagrass meadows have been damaged through fishing with a pulled or pushed gear, including traditional "samba" seine net and "sogoro" push net, as well as trampling during gleaning activities. This study focused on the operation of "samba" in Selayar Island seagrass meadows from 2014 to 2017. Although this fishing gear was prohibited under a Government regulation in 2015, it is still operated on a limited basis by local fishermen. The samba is a small scale seine net operated by 3 fishermen. A boat pulls a leading rope to which coconut leaves are attached so that it also serves as a tool to scare fish. The fishermen pull the rope around to form a trap surrounded by a semi-circular barrier of polyethylene netting. One side of the barrier net is connected to the lead rope, and the trap is gradually closed in from a wide circle until all the fish are confined in a small trap. The samba catch is generally comprised of coral reef and seagrass associated fish families such as Acanthuridae, Balistidae, Chaetodontidae, Labridae, Lethrinidae, Lutjanidae, Scaridae, Siganidae and Zanclidae. With increased surveillance of destructive activities around Selayar Island there has been some improvement in seagrass condition, so that it can be hoped that these seagrass meadows will continue to support the fish, green turtles and dugongs living there.
Seagrass conservation is crucial for climate mitigation, biodiversity protection, and food security.
Tropical coral reefs are threatened and in decline, and their future is highly uncertain. With increasing rates of climate change and rising global temperatures, people looking to coral reefs for food and income may increasingly have to rely on resources from other habitats. Efforts to protect and conserve the coral reefs we have left are critical for a suite of economic, ecological, cultural and intrinsic reasons, but there is also an urgent need to take heed of the future scenarios from coral reefs and broaden the focus of tropical marine conservation. Seagrass meadows in particular are becoming ever more important for people and planet as coral reef health declines, but these systems are also globally under stronger anthropogenic threat. We need to increase and reprioritize our conservation efforts and use our limited conservation resources in a more targeted manner in order to attain sustainable systems. For seagrass, there are practicable conservation opportunities to develop sustainable ways to respond to increased resource use. Targeted action now could restore and protect seagrass meadows to maintain the many ecosystem services they provide.
Abstract Despite the importance of coastal ecosystems for the global carbon budgets, knowledge of their carbon storage capacity and the factors driving variability in storage capacity is still limited. Here we provide an estimate on the magnitude and variability of carbon stocks within a widely distributed marine foundation species throughout its distribution area in temperate Northern Hemisphere. We sampled 54 eelgrass ( Zostera marina ) meadows, spread across eight ocean margins and 36° of latitude, to determine abiotic and biotic factors influencing organic carbon (C org ) stocks in Zostera marina sediments. The C org stocks (integrated over 25‐cm depth) showed a large variability and ranged from 318 to 26,523 g C/m 2 with an average of 2,721 g C/m 2 . The projected C org stocks obtained by extrapolating over the top 1 m of sediment ranged between 23.1 and 351.7 Mg C/ha, which is in line with estimates for other seagrasses and other blue carbon ecosystems. Most of the variation in C org stocks was explained by five environmental variables (sediment mud content, dry density and degree of sorting, and salinity and water depth), while plant attributes such as biomass and shoot density were less important to C org stocks. Carbon isotopic signatures indicated that at most sites <50% of the sediment carbon is derived from seagrass, which is lower than reported previously for seagrass meadows. The high spatial carbon storage variability urges caution in extrapolating carbon storage capacity between geographical areas as well as within and between seagrass species.
Abstract Dependence on seafood across Southeast Asia is extensive. Myanmar is no exception, but the country’s provisioning marine ecosystems are threatened. Seagrass is one habitat that is frequently overlooked in management as an important fisheries resource, despite its nursery function. In Myanmar, research on seagrass habitats is particularly sparse, and as a result, our understanding of seagrass exploitation remains limited. In this study, we provide a baseline assessment of the seagrass-associated fish assemblages at four locations in the Myeik Archipelago in southern Myanmar using mono Baited Remote Underwater Video systems. Across the sites surveyed only 12 taxa of motile fauna were recorded. Relative to other regional and global studies, this figure is meagre. Our data adds to a growing literature suggesting that the marine ecosystems of Myanmar are in a worrying state. Despite the lack of recorded seagrass associated fauna, our study revealed minimal impacts to seagrass meadows from eutrophication or sedimentation, and the meadows included appeared to be healthy. The sites with the highest number of motile fauna were within Myanmar’s only National Marine Park offering some optimism for the effectiveness of protection, but further assessments are required to allow targeted management of Myanmar’s seagrass meadows.
By-catch is considered a significant problem in large-scale fisheries yet in small-scale fisheries (SSF), employing >99% of the world's fishers, there is limited quantitative understanding of by-catch, and catches in general. We provide an assessment of by-catch from fishing gears (fyke, trawl, set trammel, and drift trammel nets) commonly used in small-scale fisheries across the globe, using a representative Sri Lankan case study and placing this in the context of local resource use patterns. We reveal evidence of how SSF generate significant finfish by-catch with potentially significant ecological impacts. Fishers targeting shrimp (fyke, trawl, and drift trammel nets) caught more non-target species than global averages (44, 44, and 67% by weight, respectively). Fishers targeting finfish (set trammel nets) caught fewer non-target species. We found that by-catch depends more on target species and gear type, supporting suggestions that SSF are not “inherently more sustainable” than their large-scale counterparts and a collective effort is required for an improved understanding of the impacts of SSF. This study highlights an additional issue of valuable food fish discards, raising questions about fisheries exploitation in the context of food security in areas where poverty and food insecurity are prevalent.
Seagrasses, flowering marine plants that form underwater meadows, play a significant global role in supporting food security, mitigating climate change and supporting biodiversity. Although progress is being made to conserve seagrass meadows in select areas, most meadows remain under significant pressure resulting in a decline in meadow condition and loss of function. Effective management strategies need to be implemented to reverse seagrass loss and enhance their fundamental role in coastal ocean habitats. Here we propose that seagrass meadows globally face a series of significant common challenges that must be addressed from a multifaceted and interdisciplinary perspective in order to achieve global conservation of seagrass meadows. The six main global challenges to seagrass conservation are (1) a lack of awareness of what seagrasses are and a limited societal recognition of the importance of seagrasses in coastal systems; (2) the status of many seagrass meadows are unknown, and up-to-date information on status and condition is essential; (3) understanding threatening activities at local scales is required to target management actions accordingly; (4) expanding our understanding of interactions between the socio-economic and ecological elements of seagrass systems is essential to balance the needs of people and the planet; (5) seagrass research should be expanded to generate scientific inquiries that support conservation actions; (6) increased understanding of the linkages between seagrass and climate change is required to adapt conservation accordingly. We also explicitly outline a series of proposed policy actions that will enable the scientific and conservation community to rise to these challenges. We urge the seagrass conservation community to engage stakeholders from local resource users to international policy-makers to address the challenges outlined here, in order to secure the future of the world’s seagrass ecosystems and maintain the vital services which they supply.
Indonesia's marine ecosystems form a fundamental part of the world's natural heritage, representing a global maxima of marine biodiversity and supporting the world's second largest production of seafood. Seagrasses are a key part of that support. In the absence of empirical data we present evidence from expert opinions as to the state of Indonesia's seagrass ecosystems, their support for ecosystem services, with a focus on fisheries, and the damaging activities that threaten their existence. We further draw on expert opinion to elicit potential solutions to prevent further loss. Seagrasses and the ecosystem services they support across the Indonesian archipelago are in a critical state of decline. Declining seagrass health is the result of shifting environmental conditions due largely to coastal development, land reclamation, and deforestation, as well as seaweed farming, overfishing and garbage dumping. In particular, we also describe the declining state of the fisheries resources that seagrass meadows support. The perilous state of Indonesia's seagrasses will compromise their resilience to climate change and result in a loss of their high ecosystem service value. Community supported management initiatives provide one mechanism for seagrass protection. Exemplars highlight the need for increased local level autonomy for the management of marine resources, opening up opportunities for incentive type conservation schemes.
Latitudinal gradients in species interactions are widely cited as potential causes or consequences of global patterns of biodiversity. However, mechanistic studies documenting changes in interactions across broad geographic ranges are limited. We surveyed predation intensity on common prey (live amphipods and gastropods) in communities of eelgrass (Zostera marina) at 48 sites across its Northern Hemisphere range, encompassing over 37° of latitude and four continental coastlines. Predation on amphipods declined with latitude on all coasts but declined more strongly along western ocean margins where temperature gradients are steeper. Whereas in situ water temperature at the time of the experiments was uncorrelated with predation, mean annual temperature strongly positively predicted predation, suggesting a more complex mechanism than simply increased metabolic activity at the time of predation. This large-scale biogeographic pattern was modified by local habitat characteristics; predation declined with higher shoot density both among and within sites. Predation rates on gastropods, by contrast, were uniformly low and varied little among sites. The high replication and geographic extent of our study not only provides additional evidence to support biogeographic variation in predation intensity, but also insight into the mechanisms that relate temperature and biogeographic gradients in species interactions.
Zostera marina is the dominant seagrass species in the Northern Hemisphere where it grows in sheltered bays and estuaries. As a consequence of its distribution its conservation is commonly threatened by poor coastal water quality. The high minimum light requirements of seagrasses results in water quality degradation (high turbidity and eutrophication) being a significant risk. Bioindicators of light stress can be used to interpret seagrass responses to light limitation and therefore act as sentinels for conservation management. However, there exists limited experimental inter-comparison of the effectiveness of multiple individual bioindicator responses. Meta-analysis suggests that rhizome sugars, shoot C:N, shoot growth, and number of leaves per shoot provide the most consistent response variables to increasing light limitation in seagrass, but this premise remains largely untested at the plant level as a direct comparison of multiple bioindicators. The present study aimed to test the morphological, physiological, and photo-physiological bioindicator responses of Z. marina to light stress applied within controlled laboratory conditions. These bioindicators were used to assign minimum light thresholds. Growth rate and photophysiological parameters (alpha, Ek, and ETRmax) were rapidly (1st week) and drastically affected by low light shade treatments (20.12 μmol photons m−2s−1 and lower). After 3 weeks at low light, significant reductions in maximum leaf length and leaf width were observed. Principal Component Analysis identified leaf length, shoot growth, shoot surface area, ETRmax, Ek, and alpha as having the strongest responses to reduced light. Shoot growth, ETRmax, Ek, and alpha were found to provide the best early warning of light limitation after 5–8 days. These results provide evidence for bioindicators of light stress in Z. marina and highlights the importance of understanding these responses for the successful management and conservation of this species.
Seagrasses are hugely valuable to human life, but the global extent of seagrass meadows remains unclear. As evidence of their value, a United Nations program exists (http://data.unep-wcmc.org/datasets/7) to try and assess their distribution and there has been a call from 122 scientists across 28 countries for more work to manage, protect and monitor seagrass meadows (http://www.bbc.com/news/science-environment-37606827). Emerging from the 12th International Seagrass Biology Workshop, held in October 2016, has been the view that grazing marine megafauna may play a useful role in helping to identify previously unknown seagrass habitats. Here we describe this concept, showing how detailed information on the distribution of both dugongs (Dugong dugon) and green sea turtles (Chelonia mydas) obtained, for example, by aerial surveys and satellite tracking, can reveal new information on the location of seagrass meadows. We show examples of how marine megaherbivores have been effective habitat indicators, revealing major, new, deep-water seagrass meadows and offering the potential for more informed estimates of seagrass extent in tropical and sub-tropical regions where current information is often lacking.
We present the results of a process to attempt to identify 100 questions that, if answered, would make a substantial difference to terrestrial and marine landscape restoration in Europe. Representatives from a wide range of European governmental and non-governmental conservation organisations, universities, independent ecologists and land managers compiled 677 questions relating to all aspects of European landscape restoration for nature and people. The questions were shortlisted by an email vote, followed by a two-day workshop, to produce the final list of 100 questions. Many of the final questions evolved through a process of modification and combination as the workshop progressed. The questions are divided into eight sections: conservation of biodiversity; connectivity, migration and translocations; delivering and evaluating restoration; natural processes; ecosystem services; social and cultural aspects of restoration; policy and governance; and economics. We anticipate that these questions will help identify new directions for researchers and policy-makers and assist funders and programme managers in allocating funds and planning projects, resulting in improved understanding and implementation of landscape-scale ecological restoration in Europe.
Abstract The significant role seagrass meadows play in supporting fisheries productivity and food security across the globe is not adequately reflected in the decisions made by authorities with statutory responsibility for their management. We provide a unique global analysis of three data sources to present the case for why seagrass meadows need targeted policy to recognize and protect their role in supporting fisheries production and food security. (1) Seagrass meadows provide valuable nursery habitat to over 1/5th of the world's largest 25 fisheries, including Walleye Pollock, the most landed species on the planet. (2) In complex small‐scale fisheries from around the world (poorly represented in fisheries statistics), we present evidence that many of those in proximity to seagrass are supported to a large degree by these habitats. (3) We reveal how intertidal fishing activity in seagrass is a global phenomenon, often directly supporting human livelihoods. Our study demonstrates that seagrasses should be recognized and managed to maintain and maximize their role in global fisheries production. The chasm that exists between coastal habitat conservation and fisheries management needs to be filled to maximize the chances of seagrass meadows supporting fisheries, so that they can continue to support human wellbeing.
In nearly all the seas around the world, in the shallow waters next to the land, are secret underwater gardens. These gardens are home to a special marine (saltwater) plant called seagrass. When seagrass grows in large areas, the habitat it creates is called a seagrass meadow. Seagrass meadows play an important role in keeping our oceans healthy and providing a home for all kinds of marine life. This marine life includes fishes that people eat, such as cod and plaice but also endangered species such as seahorses, turtles, and sea cows. Seagrasses absorb large amounts of carbon dioxide from the surrounding seawater, and so help to reduce the speed of climate change. Seagrasses help protect our coastlines from storms and rising tides because their leaves take energy out of the waves hitting the coast, and their roots act as an anchor in the underwater sand. Seagrasses also soak up nutrients and bacteria, helping to keep our seawater clean. But seagrasses around the world are being lost at a rate of about two football fields every hour. Lots of things can damage seagrass, from polluted water to boats dragging their anchors in seagrass meadows. Overfishing is a problem, since it causes an imbalance in the food chain. Unfortunately, seagrass does not get the attention it deserves because most people are unaware of its existence. We need to increase awareness of the importance of this beautiful and valuable habitat and get more people involved in monitoring and protecting seagrass, before it is too late.
Seagrass ecosystems are highly sensitive to environmental change. They are also in global decline and under threat from a variety of anthropogenic factors. There is now an urgency to establish robust monitoring methodologies so that changes in seagrass abundance and distribution in these sensitive coastal environments can be understood. Typical monitoring approaches have included remote sensing from satellites and airborne platforms, ground based ecological surveys and snorkel/scuba surveys. These techniques can suffer from temporal and spatial inconsistency, or are very localised making it hard to assess seagrass meadows in a structured manner. Here we present a novel technique using a lightweight (sub 7 kg) drone and consumer grade cameras to produce very high spatial resolution (∼4 mm pixel−1) mosaics of two intertidal sites in Wales, UK. We present a full data collection methodology followed by a selection of classification techniques to produce coverage estimates at each site. We trialled three classification approaches of varying complexity to investigate and illustrate the differing performance and capabilities of each. Our results show that unsupervised classifications perform better than object-based methods in classifying seagrass cover. We also found that the more sparsely vegetated of the two meadows studied was more accurately classified – it had lower root mean squared deviation (RMSD) between observed and classified coverage (9–9.5%) compared to a more densely vegetated meadow (RMSD 16–22%). Furthermore, we examine the potential to detect other biotic features, finding that lugworm mounds can be detected visually at coarser resolutions such as 43 mm pixel−1, whereas smaller features such as cockle shells within seagrass require finer grained data (<17 mm pixel−1).
Our understanding of global seagrass ecosystems comes largely from regions characterized by human impacts with limited data from habitats defined as notionally pristine. Seagrass assessments also largely focus on shallow-water coastal habitats with comparatively few studies on offshore deep-water seagrasses. We satellite tracked green turtles (Chelonia mydas), which are known to forage on seagrasses, to a remote, pristine deep-water environment in the Western Indian Ocean, the Great Chagos Bank, which lies in the heart of one of the world's largest marine protected areas (MPAs). Subsequently we used in-situ SCUBA and baited video surveys to survey the day-time sites occupied by turtles and discovered extensive monospecific seagrass meadows of Thalassodendron ciliatum. At three sites that extended over 128 km, mean seagrass cover was 74% (mean range 67-88% across the 3 sites at depths to 29 m. The mean species richness of fish in seagrass meadows was 11 species per site (mean range 8-14 across the 3 sites). High fish abundance (e.g. Siganus sutor: mean MaxN.site<sup>-1</sup> = 38.0, SD = 53.7, n = 5) and large predatory shark (Carcharhinus amblyrhynchos) (mean MaxN.site<sup>-1</sup> = 1.5, SD = 0.4, n = 5) were recorded at all sites. Such observations of seagrass meadows with large top predators, are limited in the literature. Given that the Great Chagos Bank extends over approximately 12,500 km<sup>2</sup> and many other large deep submerged banks exist across the world's oceans, our results suggest that deep-water seagrass may be far more abundant than previously suspected.
Excess nutrients shift the ecological balance of coastal ecosystems, and this eutrophication is an increasing problem across the globe. Nutrient levels may be routinely measured, but monitoring rarely attempts to determine the source of these nutrients, even though bio-indicators are available. Nitrogen stable isotope analysis in biota is one such bio-indicator, but across the British Isles, this is rarely used. In this study, we provide the first quantitative evidence of the anthropogenic drivers of reduced water quality surrounding seagrass meadows throughout the British Isles using the stable nitrogen isotope δ<sup>15</sup>N. The values of δ<sup>15</sup>N ranged from 3.15 to 20.16‰ (Mean ± SD = 8.69 ± 3.50‰), and were high within the Thames Basin suggesting a significant influx of urban sewage and livestock effluent into the system. Our study provides a rapid 'snapshot' indicating that many seagrass meadows in the British Isles are under anthropogenic stress given the widespread inefficiencies of current sewage treatment and farming practices. Ten of the 11 seagrass meadows sampled are within European marine protected sites. The 10 sites all contained seagrass contaminated by nutrients of a human and livestock waste origin leading us to question whether generic blanket protection is working for seagrasses in the United Kingdom. Infrastructure changes will be required if we are to develop strategic wastewater management plans that are effective in the long-term at protecting our designated Special Areas of Conservation. Currently, sewage pollution is a concealed issue; little information exists and is not readily accessible to members of the public.
Seagrass meadows are complex social-ecological systems. Understanding seagrass meadows demands a fresh approach integrating "the human dimension". Citizen science is widely acknowledged for providing significant contributions to science, education, society and policy. Although the take up of citizen science in the marine environment has been slow, the need for such methods to fill vast information gaps is arguably great. Seagrass meadows are easy to access and provide an example of where citizen science is expanding. Technological developments have been pivotal to this, providing new opportunities for citizens to engage with seagrass. The increasing use of online tools has created opportunities to collect and submit as well as help process and analyse data. Citizen science has helped researchers integrate scientific and local knowledge and engage communities to implement conservation measures. Here we use a selection of examples to demonstrate how citizen science can secure a future for seagrass.
There exists limited understanding of the long-term dynamics of the seagrass Zostera noltii and how this is influenced by anthropogenic pressures. Milford Haven is a heavily industrialised estuary and also one of the important sites for Zostera sp. in the UK. In this study we examine all available long-term spatial variability and abundance data of Zostera noltii within Milford Haven using historic datasets. Results show that Z. noltii in all sites have shown meadow expansion when compared to the first obtainable records. Little change in abundance over the past 10-15years for the two sites confirms certain seagrass populations to be robust and thriving. We hypothesise that these populations are showing a level of resilience to the high nutrient levels, disturbance and high turbidity present within the water column of the Haven.
Abstract Seagrass meadows support fisheries through provision of nursery areas and trophic subsidies to adjacent habitats. As shallow coastal habitats, they also provide key fishing grounds; however, the nature and extent of such exploitation are poorly understood. These productive meadows are being degraded globally at rapid rates. For degradation to cease, there needs to be better appreciation for the value of these habitats in supporting global fisheries. Here, we provide the first global scale study demonstrating the extent, importance and nature of fisheries exploitation of seagrass meadows. Due to a paucity of available data, the study used a global expert survey to demonstrate the widespread significance of seagrass‐based fishing activity. Our study finds that seagrass‐based fisheries are globally important and present virtually wherever seagrass exists, supporting subsistence, commercial and recreational activity. A wide range of fishing methods and gear is used reflecting the spatial distribution patterns of seagrass meadows, and their depth ranges from intertidal (accessible by foot) to relatively deep water (where commercial trawls can operate). Seagrass meadows are multispecies fishing grounds targeted by fishers for any fish or invertebrate species that can be eaten, sold or used as bait. In the coastal communities of developing countries, the importance of the nearshore seagrass fishery for livelihoods and well‐being is irrefutable. In developed countries, the seagrass fishery is often recreational and/or more target species specific. Regardless of location, this study is the first to highlight collectively the indiscriminate nature and global scale of seagrass fisheries and the diversity of exploitative methods employed to extract seagrass‐associated resources. Evidence presented emphasizes the need for targeted management to support continued viability of seagrass meadows as a global ecosystem service provider.
There exists increasing evidence that top-down ecological processes, such as herbivory are key in controlling marine ecosystems and their community structure. Herbivory has the potential to be altered by numerous environmental and ecological factors that operate at a variety of temporal and spatial scales, one such spatial factor is the influence of the marine landscape. We know little about how ecological processes, such as herbivory change throughout the marine landscape and how the effects of these processes cascade. This is because most landscape scale studies observe species richness and abundance patterns. In terrestrial systems the landscape is well documented to influence ecological processes, but empirical evidence of this is limited in marine systems. In tropical seagrass meadows direct herbivory by parrotfish can be readily observed due to the clear hemispherical bite marks they leave on the seagrass. As with herbivory in other systems, this leaf consumption is thought to assist with leaf turnover, positively influencing leaf growth. Changes in its rate and extent are therefore likely to influence the characteristics of the plant. The faunal communities of seagrass meadows alter with respect to changes in the landscape, particularly with respect to connectivity to adjacent habitats. It might therefore be expected that a key ecological process, such as herbivory will change with respect to habitat configuration and have cascading impacts upon the status of the seagrass. In the present study we examined indirect evidence of parrotfish grazing throughout the marine landscape and assessed this relative to plant condition. Seagrasses in locations of close proximity to mangroves were found to have double the amount of parrotfish grazing than sites away from mangroves. Evidence of herbivory was also found to be strongly and significantly negatively correlated to the abundance of plant attached epicover. The decreased epicover in the presence of elevated herbivory suggests increased leaf turnover. These results indicate that seagrass may have higher levels of ecosystem resilience in the presence of mangroves. Our research highlights how ecological processes can change throughout the marine landscape with cascade impacts on the resilience of the system.
Dugongs (Dugong dugon) depend on seagrass meadows for food. As such seagrass and dugong conservation should go hand in hand. Assessing dugong populations is notoriously challenging. In the most resource dependent communities Local Ecological Knowledge (LEK) is generally high and can provide an alternative to the use of expensive ecological surveys to understand dugong populations and support associated resource management decisions. Residents of the Wakatobi National Park (WNP), SE Sulawesi, Indonesia are highly dependent on marine resources for livelihoods and correspondingly LEK is high. Here LEK documents the presence of D. dugon in the WNP and infers changes in population size. Interviews with local residents in 2012-2013 revealed 99 sightings of dugongs since 1942, 48 of which occurred between 2002 and 2012, with 79.82% of respondents having seen a dugong. Declines in the frequency of sightings within the lifetime of several respondents were reported, respondents speculating that populations are reduced. This information can guide further cooperative research and conservation efforts for the protection of a vulnerable species and the seagrass habitat on which it depends.
Seagrass meadows commonly reside in shallow sheltered embayments typical of the locations that provide an attractive option for mooring boats. Given the potential for boat moorings to result in disturbance to the seabed due to repeated physical impact, these moorings may present a significant threat to seagrass meadows. The seagrass <i>Zostera marina</i> (known as eelgrass) is extensive across the northern hemisphere, forming critical fisheries habitat and creating efficient long-term stores of carbon in sediments. Although boat moorings have been documented to impact seagrasses, studies to date have been conducted on the slow growing <i>Posidonia</i> species' rather than the fast growing and rapidly reproducing <i>Z. marina</i> that may have a higher capacity to resist and recover from repeated disturbance. In the present study we examine swinging chain boat moorings in seagrass meadows across a range of sites in the United Kingdom to determine whether such moorings have a negative impact on the seagrass <i>Zostera marina</i> at the local and meadow scale. We provide conclusive evidence from multiple sites that <i>Z. marina</i> is damaged by swinging chain moorings leading to a loss of at least 6 ha of United Kingdom seagrass. Each swinging chain mooring was found to result in the loss of 122 m<sup>2</sup> of seagrass. Loss is restricted to the area surrounding the mooring and the impact does not appear to translate to a meadow scale. This loss of United Kingdom seagrass from boat moorings is small but significant at a local scale. This is because it fragments existing meadows and ultimately reduces their resilience to other stressors. Boat moorings are prevalent in seagrass globally and it is likely this impairs their ecosystem functioning. Given the extensive ecosystem service value of seagrasses in terms of factors such as carbon storage and fish habitat such loss is of cause for concern. This indicates the need for the widespread use of seagrass friendly mooring systems in and around seagrass.
Seagrass meadows are an important and threatened ecosystem.
This conference report describes the programme of the 12th International Seagrass Biology Workshop, its highlights, areas of growth for the workshop, and potential future directions for the workshop series. The report is written with an eye toward where it fits within the field of seagrass research.
There remains limited knowledge of how offshore windfarm developments influence fish assemblages, particularly at a local scale around the turbine structures. Considering the existing levels of anthropogenic pressures on coastal fish populations it is becoming increasingly important for developers and environmental regulators to gain a more comprehensive understanding of the factors influencing fish assemblages. Improving our ability to assess such fish populations in close proximity to structures will assist in increasing this knowledge. In the present study we provide the first trial use of Baited Remote Underwater Stereo-Video systems (stereo BRUVs) for the quantification of motile fauna in close proximity to offshore wind turbines. The study was conducted in the Irish Sea and finds the technique to be a viable means of assessing the motile fauna of such environments. The present study found a mixture of species including bottom dwellers, motile crustaceans and large predatory fish. The majority of taxa observed were found to be immature individuals with few adult individuals recorded. The most abundant species were the angular crab (Goneplax rhomboides) and the small-spotted catshark (Scyliorhinus canicula). Of note in this study was the generally low abundance and diversity of taxa recorded across all samples, we hypothesise that this reflects the generally poor state of the local fauna of the Irish Sea. The faunal assemblages sampled in close proximity to turbines were observed to alter with increasing distance from the structure, species more characteristic of hard bottom environments were in abundance at the turbines (e.g. Homarus gammarus, Cancer pagarus, Scyliorhinus spp.) and those further away more characteristic of soft bottoms (e.g. Norwegian Lobster). This study highlights the need for the environmental impacts of offshore renewables on motile fauna to be assessed using targeted and appropriate tools. Stereo BRUVs provide one of those tools, but like the majority of methods for sampling marine biota, they have limitations. We conclude our paper by providing a discussion of the benefits and limitations of using this BRUV technique for assessing fauna within areas close to offshore windfarms.
Seagrass meadows are vital ecosystems in coastal zones worldwide, but are also under global threat. One of the major hurdles restricting the success of seagrass conservation and restoration is our limited understanding of ecological feedback mechanisms. In these ecosystems, multiple, self-reinforcing feedbacks can undermine conservation efforts by masking environmental impacts until the decline is precipitous, or alternatively they can inhibit seagrass recovery in spite of restoration efforts. However, no clear framework yet exists for identifying or dealing with feedbacks to improve the management of seagrass ecosystems. Here we review the causes and consequences of multiple feedbacks between seagrass and biotic and/or abiotic processes. We demonstrate how feedbacks have the potential to impose or reinforce regimes of either seagrass dominance or unvegetated substrate, and how the strength and importance of these feedbacks vary across environmental gradients. Although a myriad of feedbacks have now been identified, the co-occurrence and likely interaction among feedbacks has largely been overlooked to date due to difficulties in analysis and detection. Here we take a fundamental step forward by modelling the interactions among two distinct above- and belowground feedbacks to demonstrate that interacting feedbacks are likely to be important for ecosystem resilience. On this basis, we propose a five-step adaptive management plan to address feedback dynamics for effective conservation and restoration strategies. The management plan provides guidance to aid in the identification and prioritisation of likely feedbacks in different seagrass ecosystems.
Seagrass ecosystems face widespread threat from reduced water quality, coastal development and poor land use. In recent decades, their distribution has declined rapidly, and in the British Isles, this loss is thought to have been extensive. Given increasing knowledge of how these ecosystems support fisheries production, the understanding of their potential rapid loss, and the difficulty in restoring them, it is vital we develop an understanding of the risks they are under, so that management actions can be developed accordingly. Developing an understanding of their environmental status and condition is therefore critical to their long-term management. This study provided, to our knowledge, the first examination of the environmental health of seagrass meadows around the British Isles. This study used a bioindicator approach and involved collecting data on seagrass density and morphology alongside analysis of leaf biochemistry. Our study provides, to the best of our knowledge, the first strong quantitative evidence that seagrass meadows of the British Isles are mostly in poor condition in comparison with global averages, with tissue nitrogen levels 75% higher than global values. Such poor status places their long-term resilience in doubt. Elemental nutrient concentrations and morphological change suggest conditions of excess nitrogen and probable low light, placing many of the meadows sampled in a perilous state, although others, situated away from human populations were perceived to be healthy. Although some sites were of a high environmental health, all sites were considered at risk from anthropogenic impacts, particularly poor water quality and boating-based disturbances. The findings of this study provide a warning of the need to take action, with respect to water quality and disturbance, to prevent the further loss and degradation of these systems across the British Isles.
Seagrass ecosystems represent a global marine resource that is declining across its range. To halt degradation and promote recovery over large scales, management requires a radical change in emphasis and application that seeks to enhance seagrass ecosystem resilience. In this review we examine how the resilience of seagrass ecosystems is becoming compromised by a range of local to global stressors, resulting in ecological regime shifts that undermine the long-term viability of these productive ecosystems. To examine regime shifts and the management actions that can influence this phenomenon we present a conceptual model of resilience in seagrass ecosystems. The model is founded on a series of features and modifiers that act as interacting influences upon seagrass ecosystem resilience. Improved understanding and appreciation of the factors and modifiers that govern resilience in seagrass ecosystems can be utilised to support much needed evidence based management of a vital natural resource.
Drawing attention to interactions between processes affecting biodiversity loss in marine environments and effects on food security, we draw on research in the Turks and Caicos Islands (TCI), a UK Overseas Territory in the Caribbean. Seagrass meadows provide ecosystem supporting services critical for human wellbeing. They are declining globally due to coastal development, poor land management, and destructive fishing practices. These systems are linked to traditional ways of life with multiple intangible values representing an important cultural resource for coastal communities. Using the lens of food security, we undertake interdisciplinary social–ecological research, to better understand the governance of ecosystem services and the food system in TCI. Research draws on mixed qualitative methods and data gathered via SeagrassWatch, fish surveys and meta-analysis of fish assemblages, revealing anthropogenic stressors exposing TCI to economic and environmental shocks characteristic of small island Caribbean states. We find growing concern regarding the islands׳ high dependence on food imports, coupled with declining availability of local fish and seafood across socio-economic groups. Weak governance structures put TCI׳s marine resources under increasing threat, with consequences for food security. We argue for the application of the precautionary principle, suggesting conservation actions through societal participation and stakeholder engagement.
Seagrass meadows globally are disappearing at a rapid rate with physical disturbances being one of the major drivers of this habitat loss. Disturbance of seagrass can lead to fragmentation, a reduction in shoot density, canopy height and coverage, and potentially permanent loss of habitat. Despite being such a widespread issue, knowledge of how such small scale change affects the spatial distribution and abundances of motile fauna remains limited. The present study investigated fish and macro faunal community response patterns to a range of habitat variables (shoot length, cover and density), including individual species habitat preferences within a disturbed and patchy intertidal seagrass meadow. Multivariate analysis showed a measurable effect of variable seagrass cover on the abundance and distribution of the fauna, with species specific preferences to both high and low seagrass cover seagrass. The faunal community composition varied significantly with increasing/decreasing cover. The faunal species composition of low cover seagrass was more similar to sandy control plots than to higher cover seagrass. Shannon Wiener Diversity (H') and species richness was significantly higher in high cover seagrass than in low cover seagrass, indicating increasing habitat value as density increases. The results of this study underline how the impacts of small scale disturbances from factors such as anchor damage, boat moorings and intertidal vehicle use on seagrass meadows that reduce shoot density and cover can impact upon associated fauna. These impacts have negative consequences for the delivery of ecosystem services such as the provision of nursery habitat.
The Atlantic cod (Gadus morhua) is a species of significant economic and historic importance but infamous for its decline. Apart from overfishing, the causes of this decline and its subsequent lack of recovery remain largely unresolved. Indeed, the degree to which specific habitats are important for this species remains unquantified at the scale of North Atlantic. Here, the literature on the role of eelgrass meadows (Zostera marina) as valuable nursery habitat for the Atlantic cod is reviewed and synthesized. Evidence is presented on relative densities of Atlantic cod in shallow water environments and in eelgrass meadows in comparison to alternative habitats. In addition, evidence pertaining to the ’viability gains’ attributed to the use of eelgrass meadows as nursery habitat (growth and survival) by juvenile Atlantic cod is analyzed. Although juvenile Atlantic cod use of Z. marina is found to be facultative, when possible, available literatures indicates that they may select Z. marina as a nursery habitat where they are found in high density (average of at least 246 ha−1). From their use of Z. marina habitat the juvenile Atlantic cod receives viability benefits from it, improving their chances of reaching maturation. This paper provides strong evidence that eelgrass meadows are of significant importance to contributing to Atlantic cod stocks.
Future impacts from climate change and human activities may increase the likelihood of invasions of native marine species into existing habitats as a result of range shifts. To provide an understanding of the invasion of a native seagrass species (Syringodium isoetifolium) into a tropical multi-species meadow, detailed field assessments were conducted over a six year period. After establishing in a discrete patch, the extent and standing crop of S.isoetifolium increased 800 and 7000 fold, respectively, between 1988 and 2003 (∼300-260,000 m(2) and<1 kg DW to 7596±555 kg DW). The expansion of S.isoetifolium was confined to subtidal areas and appears primarily from clonal growth. The observed expansion of this species into a new locality was found to be clearly influenced by cumulative impacts and chronic small-scale physical disturbances. This study has immediate relevance to managing impacts which influence the spread of invasive species.
The tropical seascape provides food and livelihoods to hundreds of millions of people, but the support of key habitats to this supply remains ill appreciated. For fisheries and conservation management actions to help promote resilient ecosystems, sustainable livelihoods, and food supply, knowledge is required about the habitats that help support fisheries productivity and the consequences of this for food security. This paper provides an interdisciplinary case study from the coral triangle of how seagrass meadows provide support for fisheries and local food security. We apply a triangulated approach that utilizes ecological, fisheries and market data combined with over 250 household interviews. Our research demonstrates that seagrass associated fauna in a coral triangle marine protected area support local food supply contributing at least 50% of the fish based food. This formed between 54% and 99% of daily protein intake in the area. Fishery catch was found to significantly vary with respect to village (p < 0.01) with habitat configuration a probable driver. Juvenile fish comprised 26% of the fishery catch and gear type significantly influenced this proportion (<0.05). Limited sustainability of fishery practices (high juvenile catch and a 51% decline in CPUE for the biggest fishery) and poor habitat management mean the security of this food supply has the potential to be undermined in the long-term. Findings of this study have implications for the management and assessment of fisheries throughout the tropical seascape. Our study provides an exemplar for why natural resource management should move beyond biodiversity and consider how conservation and local food security are interlinked processes that are not mutually exclusive. Seagrass meadows are under sustained threat worldwide, this study provides evidence of the need to conserve these not just to protect biodiversity but to protect food security.
Stereo Baited Remote Underwater Video systems (BRUVs) provide a quantitative sampling method for assessing mobile fauna in a range of habitat types and environments. This non-destructive and cost-effective technique is increasingly used for assessing estuarine, coastal and marine fauna. Although single camera systems have been used to assess the relative abundance (Nmax) of marine fish and invertebrates in low visibility North Atlantic near shore and coastal waters, stereo systems remain in their infancy within such environments and their use requires validation. Stereo systems that measure fish and invertebrate size enable size-frequency analysis of populations, providing critical information about life history and population status. We investigated the performance and efficacy of stereo BRUV systems within Welsh shallow coastal waters to test the effectiveness of this method. Data are presented on the capacity of the system to measure fish and invertebrate size under the constraints of low visibility (<2 m). We also present data on the required duration of deployment required to effectively sample relative fish abundance and diversity. Our study recorded 19 species of mobile fauna with species-time accumulation curves providing evidence that a minimum deployment time of 1 h is required to sample 66% of the fish species, and 2 h to sample 83%. Results suggest that the efficiency of surveys for target species (e.g. gadoids) could be maximised by modifying the sampling duration between 1 h and 2 h. The study also demonstrates that measurements of fish and invertebrate length could be taken on 41% of individuals (of those counted in relative abundance measures using Nmax), a statistic that varies between species. This indicates a need to modify the construction of the equipment for improved fish assemblage size frequency analysis. This is particularly relevant in areas and habitats where seine netting and trawling are not possible. We describe how the system can be modified for optimised usage within low visibility waters and suggest potential uses of the system.
Seagrass ecosystems are diminishing worldwide and repeated studies confirm a lack of appreciation for the value of these systems. In order to highlight their value we provide the first discussion of seagrass meadows as a coupled social–ecological system on a global scale. We consider the impact of a declining resource on people, including those for whom seagrass meadows are utilised for income generation and a source of food security through fisheries support. Case studies from across the globe are used to demonstrate the intricate relationship between seagrass meadows and people that highlight the multi-functional role of seagrasses in human wellbeing. While each case underscores unique issues, these examples simultaneously reveal social–ecological coupling that transcends cultural and geographical boundaries. We conclude that understanding seagrass meadows as a coupled social–ecological system is crucial in carving pathways for social and ecological resilience in light of current patterns of local to global environmental change.
Seagrass meadows are valuable ecosystem service providers that are now being lost globally at an unprecedented rate, with water quality and other localised stressors putting their future viability in doubt. It is therefore critical that we learn more about the interactions between seagrass meadows and future environmental change in the anthropocene. This needs to be with particular reference to the consequences of poor water quality on ecosystem resilience and the effects of change on trophic interactions within the food web. Understanding and predicting the response of seagrass meadows to future environmental change requires an understanding of the natural long-term drivers of change and how these are currently influenced by anthropogenic stress. Conservation management of coastal and marine ecosystems now and in the future requires increased knowledge of how seagrass meadows respond to environmental change, and how they can be managed to be resilient to these changes. Finding solutions to such issues also requires recognising people as part of the social-ecological system. This special issue aims to further enhance this knowledge by bringing together global expertise across this field. The special issues considers issues such as ecosystem service delivery of seagrass meadows, the drivers of long-term seagrass change and the socio-economic consequences of environmental change to seagrass.
The flow of ecosystem services from coral reefs, seagrass meadows and mangrove forests sustains the livelihoods of billions of people worldwide. Faced with the global degradation of marine and coastal ecosystems, policy makers are increasingly focusing on ecosystem service valuation techniques to encourage conservation and sustainable use of marine resources. Here we provide a review and synthesis of the available information on economic valuation techniques as applied to tropical marine habitats. Our study demonstrates the high variability and lack of consistency in outcomes from these studies. We conclude that, if the concept of ecosystem goods and services is to make a positive contribution towards managing the impacts of humans on the environment, then economic valuation approaches must reflect the inherent limitations of economic theory whilst emphasizing the complexity and heterogeneity of the natural environment and human decision making.
Although fisheries are of major economic and food security importance we still know little about specific juvenile habitats that support such production. This is a major issue given the degradation to and lack of protection afforded to potential juvenile habitats such as seagrass meadows. In the present study we investigate the role of seagrass in supporting juvenile fish of commercial value. By assessing seagrass relative to adjacent sand we determined the presence of abundant juvenile fish. Nine commercial species were recorded and the most abundant of these were Plaice, Pollock and Herring. We provide the first quantitative evidence of the presence of juvenile fish of commercial value in seagrass surrounding Great Britain. Although the species that we found in seagrass as juveniles are not obligate seagrass users the resources that seagrass meadows offer to these fish provide significant long-term fitness benefits, potentially enhancing the whole population.
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