In a new blog series, our Conservation Trainee Abi David explores some of the amazing creatures that call seagrass meadows their home. Sea snails are a hugely diverse group of marine gastropod found in all over the world. There is such a vast range of different colours, sizes, diets and
In a new blog series, our Conservation Trainee Abi David explores some of the amazing creatures that call seagrass meadows their home. The small spotted catshark (Scyliorhinus canicula) is a small shark species growing up to 1 meter long and can be seen around European and North African coastlines. They
In a new blog series, our Conservation Trainee Abi David explores some of the amazing creatures that call seagrass meadows their home. The snakelocks anemone is a funny looking creature commonly found around the UK. They have up to 200 long, wavy tentacles and can grow on average to about
In a new blog series, our Conservation Trainee Abi David explores some of the amazing creatures that call seagrass meadows their home. The Brent Goose Branta bernicla is of a similar size to a Mallard duck, making it one of the smallest goose species in the world. They are a
Dr Richard Unsworth, Chief Scientific Officer at Project Seagrass, along with 35 other leading scientists from across the UK, responds to proposals from the UK government to make licensing for marine restoration more complex and costly. Dear Rt Hon Steve Reed OBE MP and team, This letter sets out our
In a new blog series, our Conservation Trainee Abi David explores some of the amazing creatures that call seagrass meadows their home. Sea hares are odd looking creatures. They are mostly soft bodied but have a small internal shell, which separates them from their close relatives – sea slugs. The
In a new blog series, our Conservation Trainee Abi David explores some of the amazing creatures that call seagrass meadows their home. Cuttlefish are molluscs and join squid and octopuses in the Cephalopod family. Predominantly found in temperate and tropical areas, 120 species can be found around the world. Cuttlefish
Around the archipelago of Orkney, are some of the UK’s most pristine seagrass meadows. With numerous sheltered bays, low numbers of inhabitants, and crystal-clear waters, Orkney’s shores provide the ideal conditions for seagrass. However, much remains unknown about these important ecosystems. The Highland Park funded Sjogras Partnership was established to
Artificial reefs might help to restore the ocean’s ability to fight against climate change. The reefs boost the productivity of seagrass meadows by attracting fish, which can improve the ability of these habitats to lock up more carbon dioxide beneath the waves. Breeze blocks placed in one of the ocean’s
For approximately 3,000 years, generations of green sea turtles have returned to the same seagrass meadows to eat. This was discovered by Willemien de Kock, a historical ecologist at the University of Groningen, by combining modern data with archaeological findings. Sea turtles migrate between specific breeding places and eating places
In a new blog series, our Conservation Trainee Abi David explores some of the amazing creatures that call seagrass meadows their home. Sea snails are a hugely diverse group of marine gastropod found in all over the world. There is such a vast range of different colours, sizes, diets and life strategies within the sea snail community. These are fascinating little creatures that deserve a lot more attention than they receive! A big issue for sea snails inhabiting shallow coastal areas is desiccation – drying out when the tide goes out. Some species, like periwinkles, will group together in rock crevices and excrete a gluey mucus to hold them in place and retain moisture. A lot of species have an operculum. This structure is attached to their foot and acts as a trapdoor. When the snail retreats into its shell, the operculum will seal shut, preventing moisture from escaping and the snail from drying out. Snail mating behaviour is both odd and fascinating. There are so many variations in the sea snail world – from self-fertilising hermaphrodites to standard sexual reproduction. Some species are your standard dioecious set up – within the species there are male individuals and female individuals where gametes from each are needed for reproduction. For example, the common whelk Buccinum undatum has separate males and females. The females will release pheromones to attract males and fertilisation will happen internally, allowing the production of egg capsules. Each capsule contains between 600 and 2000 eggs. Despite being in the same egg capsule, the developing embryo may still have different fathers as the females can mate multiple times and store sperm until the environmental conditions are perfect. Other snail species will gather in groups and release their gametes straight into the water column for fertilisation to take place. Shannon Moran / Ocean Image Bank Hermaphroditism is where one individual produces both male and female gametes. Some species such as bubble snails and mud snails are simultaneous hermaphrodites – they can produce both sets of gametes at once, meaning they can self-fertilise. Protandrous sequential hermaphroditism is when the individual started out as male but changes sex to become a female at some point throughout their lives. Species in the genus Crepidula (slipper snails) express this behaviour. The change in sex is thought to be influenced by their social situation – number, sex and size of other individuals in the vicinity. Some species will carry around their offspring on their shells. Males of the whelk species Solenosteira macrospira will carry the offspring of up to 25 other males. When mating, the female will glue capsules containing hundreds of eggs onto the males shell. As the eggs hatch, some of the first to break free will eat their siblings that are still developing inside the egg. Other species will glue their eggs to solid structures in the environment and leave them to raise themselves. Eggs can hatch into larvae which will travel with currents to help dispersal and mix populations and then settle down to develop after a few weeks. In other species, tiny, fully formed versions of the adults will hatch. Why am I telling you about sea snails? Because they love seagrass! Uk species such as the mud snail Peringia ulvae, banded chink snail Lacuna vincta, the bubble snail Haminoea navicular and perhaps the most recognisable common periwinkle Littorina littorea and netted dog whelk (Tritia reticulata) are all known to use seagrass meadows in at least one stage of their life cycle. Some snails, such as the dog whelk, will lay their eggs on the leaves of seagrass, attaching them with a mucus to hold them firm and preventing coastal currents from dislodging the eggs. Some species will eat the algae growing on the seagrass leaves. They use sharp, tiny teeth like structures to scrape the algae off the leaves. This is very important for the health of seagrass as too much algal growth will smother the plant, preventing sufficient light for photosynthesis to reach the leaf. There is evidence showing the presence of snails on seagrass increases leaf length and nutrient content (Jiang et al., 2023). Other benefits of these little critters Sea snails play a huge role in ecosystems and coastal environments. Their role as an indicator species helps us understand environmental health and can be used to measure levels of pollution and habitat quality. In some cultures, they are harvested for their meat and shells, creating important income streams for coastal communities. Snails form a vital part of many species diets, including birds, crabs and fish. Some species are detritivores – they will eat dead and decaying organic matter on the sea floor. This is a very important role as it prevents nutrient build up which can lead to algae blooms and disease outbreaks. Sea snails are even being used in scientific research to advance technologies. All snails have tiny teeth-like structures on their radula (a tongue-like mouthpart), however in some species these are super strong. Patella vulgate, a species of limpet, have some of the strongest in the world – the strength of their teeth is comparable to some of the strongest commercial carbon fibres and can withstand the pressures that turn carbon into diamonds (Sea Snail’s Teeth: Are They the Strongest Biomaterials in the World?, 2019). These properties are being studied for use in improving and adapting technology used in building planes, boats and dentistry. Researchers are investigating compounds in the venom some sea snails produce for possible use in medicinal drugs for pain relief and diabetes (Sea snail poison promises new medicines, 2018). If you want to find out more about these strange little creatures, I’d recommend these articles to start: 5 Sensational Sea Snail Species Sea Snail References: Sea snail poison promises new medicines | Research and Innovation. (2018). Projects.research-And-Innovation.ec.europa.eu. https://projects.research-and-innovation.ec.europa.eu/en/projects/success-stories/all/sea-snail-poison-promises-new-medicines Eren , R. (2019). Sea Snail’s Teeth: Are They the Strongest Biomaterials in the World? [online] Fountain Magazine. Available at: https://fountainmagazine.com/all-issues/2019/issue-132-nov-dec-2019/sea-snail-s-teeth-are-they-the-strongest-biomaterials-in-the-world. Jiang, Z., He, J., Fang, Y., Lin, J., Liu, S., Wu, Y. and Huang, X.
In a new blog series, our Conservation Trainee Abi David explores some of the amazing creatures that call seagrass meadows their home. The small spotted catshark (Scyliorhinus canicula) is a small shark species growing up to 1 meter long and can be seen around European and North African coastlines. They generally live in shallow coastal areas and rarely go deeper than 100 meters around the British Isles, but in areas such as the Mediterranean they have been spotted swimming down to 400 meters deep. They love sandy, muddy or rocky seafloors where they feed on crab, molluscs and fish which they detect with their strong sense of smell and electrical sensors located in its snout. Sharks have really interesting skin. Tiny teeth-like structures called dermal denticles cover their whole body, giving the shark a course, sandpapery texture. These provide the shark with an armour like protection from other predators, but also from parasites, algae and barnacles that might think a sharks body would make a good home. Each denticle has a blood flow and is covered in dentine – the same thing as human teeth – to make them extra solid structures and are discarded and replaced throughout the sharks lifetime. Denticles also reduce drag whilst swimming, allowing the creatures to swim at high speeds. This particular property has been of interest to companies, who have mimicked the structure of the denticles with synthetic materials for human use. One such example is Speedo, who created a material called “Fastskin” for swimsuits that was so good it was banned from competitions, including the Olympics! Small Spotted Catshark egg in Seagrass Spotted catsharks are oviparous – meaning they lay their young in eggs to develop outside of the body. The female will lay her eggs in pairs in sheltered, shallow coastal areas. To keep the eggs safe during development, the female will attach the egg case to a solid structure – usually seaweed or seagrass. Once ready to lay the eggs, long tendrils at each corner of the egg will appear first. These are attached to a seagrass shoot or seaweed by the female swimming in tight circles around it. Once these tendrils are attached, the female will circle faster, pulling the rest of the egg from the cloaca and making sure it is firmly attached to the chosen structure. The eggs will develop for 8-9 months, depending on the sea temperature and then hatch into small versions of the adults. It is common to see spotted catshark egg cases washed up on beaches around the UK. If you’ve come across a small, roughly 5 -7 cm long, thin case with curly tendrils at each corner, chances are it was a spotted catshark egg case! Usually these are empty, but sometimes they will have been dislodged and wash up with the embryo inside. If you find one of these – made sure to put it in a deep rock pool and anchor it down so it doesn’t float back onto the beach! What is a spotted catsharks relationship with seagrass? This catshark uses seagrass mainly as a nursery for its young. As mentioned before, the females will wrap the tendrils of the egg cases around a solid structure such as seagrass, ensuring it doesn’t get washed away in currents and keeping the developing embryo safe. Dense seagrass meadows make perfect nursery’s once the sharks hatch from their eggs too. The meadows provide shelter from predators as well as a wide variety of food for the baby spotted catsharks to practice hunting. Adult spotted catsharks may also be spotted around seagrass meadows as a lot of their prey likes to hide between the shoots, such as crabs and small fish. Why is this species important? Unlike some of the other species mentioned in this blog series, spotted catsharks have little commercial/ human use. Some communities eat them but on a large commercial scale, they have little value. However, within ecosystems it has a couple of important roles. It is a mid-level predator, meaning it eats a wide variety of smaller creatures as part of its regular diet, but also can be prey for other bigger species, like other sharks and seals. The role of a predator is vital in maintaining healthy populations. For example, the spotted catshark loves to munch on crab, which can be quite destructive animals when their population grows too large. By keeping crab numbers at a healthy level, catsharks help maintain functioning ecosystems and happy seagrass meadows. Also, scientists can use spotted catsharks as indicator species. If they are present, it means the habitat has a healthy number of different species as the sharks wouldn’t stick around an area that doesn’t have enough food to support them. Reference : https://www.ebsco.com/research-starters/science/small-spotted-catshark
In a new blog series, our Conservation Trainee Abi David explores some of the amazing creatures that call seagrass meadows their home. The snakelocks anemone is a funny looking creature commonly found around the UK. They have up to 200 long, wavy tentacles and can grow on average to about 8cm wide. These anemones are common in rock pools as they like to attach themselves to a solid surface in sunny spots, however they are also commonly found attached to seagrass leaves. Their diet generally consists of plankton, tiny crustaceans, and small fish. To catch live prey, they use sticky stinging cells in their tentacles called nematocysts which emit a paralysing, sometimes lethal, venom on contact. This venom is mostly harmless to humans, generally only causing a small rash on contact. Snakelocks anemones in the Isle of Wight Snakelocks anemone tentacles are usually a deep green with purple tips. A symbiotic algae called zooxanthellae located in the tissue helps the anemone to survive by producing essential nutrients like glucose via photosynthesis. In return, the algae receive a safe stable environment to live. Due to this need for photosynthesis, the anemone needs light so generally won’t live more than 12 meters deep. Unlike other anemone species, the snakelocks rarely retracts its tentacles, allowing them to make the most of any sunlight. A recent study discovered that snakelocks anemones move their tentacles throughout the day to follow the sun whilst its body remains in one place, similar to sunflowers! This is commonly seen in plants, but never before in animals. It is thought this movement is caused by the algae living within their tentacles. You can read more about this here. The snakelocks anemone is a Cnidarian – a group of aquatic invertebrates also including jellyfish and corals. Cnidarians have a fascinating life cycle but to put it simply, they generally have 2 body forms – a swimming medusae and a sessile polyp stage and can reproduce either sexually or asexually. However, the snakelocks anemone completely lacks the free-swimming medusa stage. This means once the sperm and eggs are fertilised, which happens externally in the water column, the larvae drop down to create another polyp from which tentacles will grow. A more common method of reproduction is longitudinal fission. This asexual method involves the anemone splitting in half to create 2 identical individuals. This process can take between a couple of minutes to a few hours. So what is a snakelocks anemone’s relationship with seagrass? These anemones are commonly found in seagrass meadows around the UK. They attach and live on the leaves, providing the anemone with a stable, sunny habitat. The seagrass protects the anemones from drying up at low tide, meaning the anemone can be in shallower waters and get more sunlight without the risk of desiccation. Are snakelock anemones an important species? Of course! Every species has an important ecological niche, i.e. a role it plays within its environment that helps maintain a healthy functioning ecosystem. Some small creatures like to live within the tentacles of the snakelock anemone, such as the incognito goby, shrimps and Leach’s spider crabs. The tentacles of the anemone provide shelter and protection from predators. Human populations also use snakelocks anemones. For example, in southwest Spain and Sardinia it is a common dish, served marinated in vinegar and deep fried.
In a new blog series, our Conservation Trainee Abi David explores some of the amazing creatures that call seagrass meadows their home. The Brent Goose Branta bernicla is of a similar size to a Mallard duck, making it one of the smallest goose species in the world. They are a highly social species and form strong bonds within the groups they live in. If you spot a group of Brent Geese, look out for the ‘compass’ goose – this is the leader of the group and will lead the way between foraging areas. Depending on the species of Brent Goose, individuals may have a dark or light belly, along with a dark head and body, with adults having a small white patch on their necks. They can be seen throughout the UK during the autumn/ winter months in marine, intertidal or wetland areas. Dark bellied Brent Geese. Photo Credit Emma Butterworth Migration Just like many other bird species, Brent Geese carry out an annual migration. They spend summer months breeding and raising chicks in the Arctic and migrate to Western Europe for more temperate winters. Generally, the individuals we get overwintering here in the UK are from Siberia. Due to these long migration routes and small body size, Brent Geese have a high food demand meaning they heavily rely on stopovers to refuel. Their most popular stopover sites tend to be Zostera marina meadows. Large numbers of Brent Geese have been spotted for several weeks each year in Izembek Lagoon (Alaska), lagoons in Baja California, the German/Danish Wadden Sea, the Golfe du Morbihan (France), British estuaries, and the White Sea (Western Russian Arctic). Diet Brent Geese are heavily herbivorous and mainly consume seagrass. They have relatively short necks and lack the ability to dive so can only reach plants at low tide or in shallow water. Interestingly, during breeding season the geese will consume a wide range of plant species but show a strong preference for Zostera species throughout non-breeding seasons due to the high digestibility and nutritional value compared to other options. They have been observed eating both the leaves and rhizomes of the plants. Importance of seagrass for Brent Goose populations As mentioned previously, Brent Geese rely heavily on seagrass during their migrations. This can be seen in population trends. In the 1930s, Zostera species across the North American coast were heavily affected by wasting disease and there was a significant population decline. At the same time, a steep decline in Brent Goose population was also observed on both sides of the Atlantic, with estimates ranging from 75 – 90% of populations lost. During the 1950s, there was a good recovery of seagrass beds in the areas previously affected, which was followed by a recovery of Brent Goose populations from around 15,000 to over 100,000. Similar smaller scale events like this have been observed, showing just how important healthy seagrass meadows are for species like the Brent Goose that rely so heavily on them. Are Brent Geese bad for seagrass restoration? It could be argued that Brent Geese are bad for seagrass and bad for seagrass restoration due to their consumption of the plants. However, there is a bit more to it than that. Seagrass provides services for many species, and a food source is one of those. Anecdotally, there have been instances where restoration has occurred only for geese to come along and eat all of the freshly planted shoots, which really isn’t ideal. In the scientific literature, there is mixed evidence about how much the geese will consume and how this affects the meadow’s health, which makes it difficult to quantify their impact. Some research notes that the percent the geese eat out of the whole meadow is actually quite small and a healthy meadow should have no issue recovering from any damage. The geese could even be useful in seagrass restoration. They tend to only be seen where food is available and as such are an indicator species for the health of an ecosystem. Like all birds, they are useful for their ability to spread nutrients and seeds through their faeces, helping to spread plant species more widely than they would on their own. Additionally, they are an important food source for predators such as foxes and raptors in their Arctic breeding grounds. Brent Geese, like any other species using seagrass, are carrying out behaviours that have evolved over thousands of years. Therefore, the question of whether geese are bad for seagrass restoration is not a straightforward one. What do you think? Sources: Ganter, B. (2000). Seagrass ( Zostera spp.) as food for brent geese ( Branta bernicla ): an overview. Helgoland Marine Research, 54(2–3), 63–70. https://doi.org/10.1007/s101520050003 Find out more the role that seagrass plays for migratory birds here.
Dr Richard Unsworth, Chief Scientific Officer at Project Seagrass, along with 35 other leading scientists from across the UK, responds to proposals from the UK government to make licensing for marine restoration more complex and costly. Dear Rt Hon Steve Reed OBE MP and team, This letter sets out our response as leading scientists, practitioners, and NGOs to the DEFRA consultation “Marine licences: changes to fees, exemptions and self-service licences”. We believe the proposed increases in fees and restrictions for marine licences will seriously undermine restoration efforts, making an already difficult activity even more challenging and, in many cases, unviable. The current licensing system for marine restoration is already unjust and fundamentally at odds with the UK Government’s national and international commitments. To introduce additional fees, administrative burdens, and restrictions at this time is, quite frankly, perverse. We specifically oppose: Any increase in fees for marine restoration licences. The urgent need is to remove fees entirely, not add to them. Further restrictions and additional charges on marine restoration projects larger than 5 hectares (we need marine restoration exemptions from this). Evidence clearly shows that scaling up restoration delivers greater resilience and enhanced ecosystem service (natural capital) benefits compared with small, fragmented projects. We specifically request: Practitioners need DEFRA to create a simplified, consistent, cost-free, and science-based licensing system for marine and coastal conservation. Currently, licensing is one of the most significant barriers to restoring the health of the UK’s seas. We see these proposed changes under the consultation as a missed opportunity to create such a system. The urgency could not be greater. Our climate and natural systems are breaking down, and the ocean is in crisis. In each of the last three summers (2023–2025), UK seas have endured unprecedented marine heatwaves. Never before has there been such a critical need for healthy coastal ecosystems that can bolster resilience, buffer climate impacts, and support food security. Yet our habitats have been decimated and continue to decline with DEFRA’s own assessment concluding that the UK marine environment is failing on 13 out of 15 indicators. Marine restoration is not optional; it is essential for our collective future. Restoring and conserving ocean habitats is also a legal obligation. The UK is a signatory to the Kunming–Montreal Global Biodiversity Framework and, under the Environment Act 2021, has binding targets for nature recovery. These commitments require all public bodies, including seabed owners to conserve and enhance biodiversity. The UK has already missed the Aichi Biodiversity Targets, largely due to regulatory barriers of the very kind now being proposed. Repeating these mistakes would be indefensible. The benefits of a streamlined licensing system are profound. It would enhance our capacity to tackle the climate and biodiversity crises, strengthen coastal resilience, and improve national food security. International examples demonstrate that simplified frameworks accelerate recovery and generate long-term ecological and social benefits. At conferences such as ReMeMaRe, UKSS, and the Seascape Conference, frustration with England’s current licensing regime has been a recurring theme. The system is widely regarded as unpredictable, inconsistent, costly, and burdensome, treating restoration projects as if they damage rather than enhance the marine environment. This not only delays urgent work but risks deterring vital investment in ocean recovery. The state of our marine environment illustrates the scale of the problem: estuaries are degraded, mudflats retreating, saltmarshes fragmented, and most seagrass meadows lost. Remaining habitats are scarce and highly vulnerable to climate change. Immediate reform is essential. Wales and Scotland are already moving in the right direction. Dialogue and regulatory reforms are creating enabling environments for restoration. England must now do the same. Without urgent change, regulation will remain a barrier to the large-scale environmental renewal that is desperately needed. We no longer have healthy ecosystems to use as restoration baselines. Historic habitats such as oyster reefs have vanished, while global heating accelerates ecological change. Restoration must therefore look forward, building climate-resilient ecosystems that reflect future needs rather than only past states. To do so, we need a legal and regulatory framework that supports ambition. The Kunming–Montreal Framework and the Environment Act 2021 require bold action, but these targets cannot be met without enabling legislation. In addition to the consequences of further restrictions on marine restoration for biodiversity, we also believe these restrictions place further restrictions upon our ability to reach Net Zero, and therefore see this as an issue not only for DEFRA but also for DESNZ. We therefore call on the Government to act swiftly to reform the licensing system for marine and coastal restoration. This is a practical and achievable step that would deliver immediate benefits for biodiversity, climate resilience, and food security. As scientists and practitioners at the forefront of UK marine research and restoration, we would welcome the opportunity to meet with you and your team to discuss solutions and pathways for progress. Yours sincerely, Dr Richard Unsworth FRSB, FHEA Associate Professor (Swansea University), Chief Scientific Officer (Project Seagrass) Signed on behalf of the following: Prof Martin J Attrill, Professor of Marine Ecology, University of Plymouth Dr Dan Barrios-O’Neill, Head of Marine Conservation, Cornwall Wildlife Trust Prof Michael Chadwick, King’s College London Sarah Chatfield, Nature Recovery Partnership Manager, Chichester Harbour Conservancy Dr Leanne Cullen-Unsworth, Chief Executive, Project Seagrass Dr Aline da Silva Cerqueira, Sussex Bay & King’s College London Dr Tim Ferrero, Senior Specialist – Hampshire & Isle of Wight Wildlife Trust Zia Fikardos, Marine Policy Officer, Royal Society for the Protection of Birds (RSPB) Angus Garbutt, Principal Scientist, UK Centre for Ecology & Hydrology Chris Graham, Head of Ocean Regeneration, Marine Conservation Society Tom Godfrey, Founder, Earth Change Dr Ian Hendy, Coastal Ecologist, Senior Lecturer, University of Portsmouth Chloë James, Seagrass Project Officer, Cornwall Wildlife Trust Prof Chris Laing, University of Exeter Dr Sally Little, Nottingham Trent University Louise MacCallum, Solent Seascape Project Manager, Blue Marine Foundation Niall McGrath, CEO, Robocean Ltd. Anouska Mendzil, Senior Science Officer, Project Seagrass & Swansea University Nigel Mortimer, Estuaries Officer, South Devon National Landscape Estuaries Partnership Dr Simon J. Pittman, School of Geography
In a new blog series, our Conservation Trainee Abi David explores some of the amazing creatures that call seagrass meadows their home. Sea hares are odd looking creatures. They are mostly soft bodied but have a small internal shell, which separates them from their close relatives – sea slugs. The sea hare gets it name from the two rhinophores sticking out from the top of the head as they look like the ears of hares. However, these appendages aren’t used for hearing, but for taste and smell. A sea hare’s favourite snack is seaweed, but they also eat seagrass. Interestingly, the colour of the seaweed species most prominent in their diet influences the colour of the sea hare individual, for example: diets made from mostly sea lettuce will lead to a green body colour and reddish-maroon sea hares will be eating mostly red seaweeds. Sea Hare on seagrass. Photo Credit Lewis M Jefferies A Sea Hare within an Orcadian seagrass meadow. Photo Credit Lewis M Jefferies When threatened, they can produce a cloud of ink which the sea hare can hide in to confuse predators. Scientists have found that this ink has antibacterial properties, thought to be useful in healing wounds and combating harmful bacteria. Additionally, they can produce a slime on their skin which makes the sea hare less tasty and puts predators off from eating it. Sea hare species can range from 2 to 70cm, but the ones found around the UK – Aplysia punctata or dotted sea hare – are on the smaller size of 7 – 8cm and can be found throughout the year in rock pools and shallow waters. They lay their eggs in long string-like structures attached to seagrass, with the seagrass meadow acting as a nursery environment when the eggs hatch. They are hermaphrodites, meaning individuals have both male and female mating organs. Despite this, they still reproduce with others, usually in a line with multiple individuals. Sea Hares in seagrass As well as seaweeds, sea hares will consume seagrasses too. As with many marine species, seagrass meadows provide an important nursery habitat. By attaching developing eggs to seagrass leaves, the eggs are protected from strong currents and predators, as well as providing a food source for newly hatched sea hares. Some species, such as the Phyllaplysia taylori or eelgrass hare, live solely on seagrass. Evidence has shown presence of sea hares increases seagrass productivity as a result of grazing on epiphytes on the leaves. A build-up of too many epiphytes will block the leaves ability to photosynthesize, so these little creatures can be very handy for us seagrass scientists! Sea Hare (with egg strings) on a blade of seagrass. Photo credit Lewis M Jefferies But do sea hares benefit society? Yes! They form an important part of diets around the world. For example, in Hawaii, people wrap the sea hare in to leaves and cook it in an underground oven, called an imu. In the Philippines, egg strands, known as lokot, are eaten raw with vinegar and spices. Samoa, Kiribati and Fuji also have sea hares as part of the traditional diet. Often it is women that will go out and collect the sea hares at low tide on mudflats and seagrass meadows and then sell them at markets, so sea hares have an important economic benefit to these societies too. For further information about how grazers such as the sea hare are beneficial to seagrass, look at this article.
In a new blog series, our Conservation Trainee Abi David explores some of the amazing creatures that call seagrass meadows their home. Cuttlefish are molluscs and join squid and octopuses in the Cephalopod family. Predominantly found in temperate and tropical areas, 120 species can be found around the world. Cuttlefish have an internal shell, known as the cuttlebone, which helps with buoyancy. By changing the gas to liquid ration, they can determine how much they float. Their diet generally consists of small molluscs, crabs, shrimp, small fish, octopuses and worms. To catch their prey, they use suckers attached to their two tentacles, which shoot out and grab unsuspecting victims. The flamboyant cuttlefish (Metasepia pfefferi) even uses venom to subdue its prey. To escape predators themselves, they can propel themselves forwards or backwards by expelling a powerful jet of water from their mantle cavity (main body). Cuttlefish in seagrass, Cornwall, UK. Credit Shannon Moran Ocean Image Bank Cuttlefish. Credit François Baelen Ocean Image Bank Like other cephalopods, cuttlefish have quite sophisticated eyes. They have two spots of highly concentrated sensor cells on their retinas – meaning they can look both forwards and backwards at the same time. This ability is aided by their W- shaped pupil, giving them a wide field of vision. It is thought cuttlefish eyes are fully developed before hatching, enabling them to begin observing their environment whilst still in the egg. Part of why I love cuttlefish so much is their ability to change colour using skin cells called chromatophores. They do this by expanding and contracting these cells to resemble colours and patterns found within their environment for camouflage and warning off predators. I could go on a lot more about this amazing ability, but this article by Gilmore, Crook, & Krans, gives a nice, detailed overview. So how do they utilise seagrass? Seagrass is an important habitat for cuttlefish. Many other creatures such as crabs, worms and snails call seagrass home, basically providing them with an all you can eat buffet. Additionally, like many other species, cuttlefish lay eggs on seagrass leaves as meadows provide a sheltered environment safe from currents and tides that may wash eggs away. Once these eggs have hatched, seagrass meadows provide a safe nursery site from predators. Cuttlefish eggs in seagrass, Dale, West Wales Why do we need cuttlefish? As with every other species on the planet, cuttlefish have their own unique purpose in the ecosystem. They are predators of a variety of species, meaning they help control populations – which is important to maintain a healthy ecosystem balance. They themselves are prey for commercial fish species such as Atlantic cod. In parts of the Mediterranean, Asia, and Europe, they provide an important part of human diets. Cuttlefish are, in my opinion, a hugely underrated species. Not only are they super cool with their colour changing abilities, but they are also an important part of many habitats and ecosystems across the globe. More information: Gilmore, R., Crook, R. & Krans, J. L. (2016) Cephalopod Camouflage: Cells and Organs of the Skin. Nature Education 9(2):1
Around the archipelago of Orkney, are some of the UK’s most pristine seagrass meadows. With numerous sheltered bays, low numbers of inhabitants, and crystal-clear waters, Orkney’s shores provide the ideal conditions for seagrass. However, much remains unknown about these important ecosystems. The Highland Park funded Sjogras Partnership was established to bridge these knowledge gaps. Now in its fourth year, Professor Joanne Porter’s MSc International Marine Science students from Heriot Watt University Orkney and Dr. Elizabeth Lacey and Dr. Calum Hoad from environmental charity Project Seagrass have focused on developing our scientific understanding of the pristine seagrass meadows found around Orkney’s shores, with mapping and quantifying the ecosystem services provided by Orcadian seagrass being top priorities. Often referred to as ‘marine powerhouses’, seagrass meadows can provide numerous benefits for the surrounding environment. Havens of biodiversity, they provide habitat, food, and shelter to thousands of species of fish, invertebrates, mammals, reptiles, and birds. As important fishing grounds, seagrass meadows provide access to food sources and support the livelihoods of millions of people around the world. Seagrass meadows can also trap carbon within the seabed and, if left undisturbed, can store this for millennia. Locating and mapping Orcadian meadows enables local protection, while gathering data to understand these habitats furthers seagrass science, impacting broader understanding and wider conservation efforts. Year 1 | 2022 During the first year of the partnership, then Heriot Watt University student Katy Waring set out to develop methods to assess the ecosystem services provided by seagrass around Orkney. This involved surveying seagrass meadows around Orkney’s shores using Baited Remote Underwater Videos (BRUVs), a non-invasive research tool, to collect data. Katy worked with local engineering firm Hamnavoe Engineering to design and develop the BRUVs and deployed them off Stronsay’s shoreline in the bay of Franks during the 2022 survey. This research provided evidence of the vital ecosystem service that Orcadian seagrass plays in providing habitats and spawning grounds to a variety of marine species, including Pollock and Atlantic Cod. Year 2 | 2023 In year two, then student Oliver Lee supported Dr Esther Thomsen of Project Seagrass to map seagrass meadows using a WINGTRA drone. Building on Katy’s research, Oliver went on to further document the biodiversity within Orcadian seagrass meadows through subtidal surveys at Mill Bay, Stronsay and at Tankerness, Orkney mainland. His research found an abundance of species inhabiting Orkney’s seagrass – further emphasising the significant role that these meadows have for the marine environment. Year 3 | 2024 Year 3 of the partnership supported the research of then students, Emily Powers and Emma Retson. Emily undertook surveys to understand variances of biodiversity in seagrass beds around the Isles. Her research explored how species diversity may be impacted by abiotic factors (such as seabed depth and tidal current flow) and found a higher richness of biodiversity in beds exposed to high tidal ranges and stronger tidal streams. Emma’s research focused on comparing infauna (animals living in the sediment beneath the seafloor) data from different sites and the influence of seagrass density on this. Sediment samples were extracted to enable the biodiversity associated within the sediment to be quantified. Local Stromness based expert Inga Williamson of Biotikos Ltd providing taxonomic expertise in identification of the infaunal organisms. Looking ahead In the summer months of 2025, the Sjograss Partnership will continue working together to better understand the health and extent of Orkney’s seagrass. This year, Dr. Elizabeth Lacey plans to establish ‘sentinel’ sites around the Orkney archipelago. These sites will be chosen to represent the characteristics of seagrass habitats across the islands. By routinely monitoring the sentinel sites into the future, the Sjograss Partnership will improve our picture of the dynamics and drivers of seagrass health in Orkney. In turn, this understanding could help us understand how and why seagrass is changing across Scotland. Within these sentinel sites, HWU PhD candidate Millie Brown is working on ecosystem services (carbon sequestration) of blue carbon habitat mosaics, as part of her SMMR funded scholarship research and MSc project student Alisha Underwood will be studying properties of the sediment associated with seagrass at Finstown and Tankerness. In addition, as part of setting up the sentinel sites, Dr. Calum Hoad from Project Seagrass will be experimenting with high-tech methods for mapping the extent of each seagrass meadow. In the water, the team will use a remotely controlled boat to capture echosounder data. In the air, the team will use sophisticated sensors attached to drones to take thousands of images of the seagrass meadows. From space, satellites will take pictures of Orkney every few days while the team is on the ground. By combining all of these types of data with data collected by hand (and snorkel!), the team will map the sentinel seagrass meadows of Orkney. Examining the strengths and weaknesses of each data source will help the team think about how best to map seagrass across the rest of Orkney, Scotland, and the UK. Hear more in person and get involved! The Sjogras Partnership will be working at seagrass meadows across Orkney from 19th July until 1st August. There are a few opportunities to meet the team in person, to learn more about seagrass, and even to see some seagrass in person: Renewables Revolution Open Day, 2-5pm on 23 July 2025, at the Orkney Research and Innovation Centre, where the Sjogras Partnership will be showcasing Orkney’s seagrass. A guided snorkel over a local seagrass meadow near Kirkwall on Sunday 27th July. Sign up will be necessary and spaces limited. The Orkney International Science Festival Family Day, 10-12.30 and 1-3pm on 6th September, at the Pickaquoy Centre, Kirkwall, where Project Seagrass and the local Heriot Watt team will be ready to talk all about seagrass science. We hope to see you there!
Artificial reefs might help to restore the ocean’s ability to fight against climate change. The reefs boost the productivity of seagrass meadows by attracting fish, which can improve the ability of these habitats to lock up more carbon dioxide beneath the waves. Breeze blocks placed in one of the ocean’s most endangered habitats provide an unexpected lift for fish. Seagrass meadows are found across the world, reaching from the tropics up into the lower reaches of the Arctic circle. They are incredibly valuable habitats, providing a nursery for young fish as well as sucking vast quantities of carbon dioxide from the atmosphere. However, with an area of seagrass the size of a football pitch being lost every 30 minutes, it’s more important than ever to find out how to turn things around. A new study in the Caribbean has shown that artificial reefs can help to bolster their growth in the tropics, even as threats such as fishing and nutrient pollution continue. Dr Jacob Allgeier, a co-author of the paper, says, ‘By attracting fish, whose faeces provide concentrated nutrients for the seagrass, the artificial reefs increase the primary production of the entire ecosystem.’ ‘We are now investigating how this cascades up the food web. The new energy has to go somewhere, so we are quantifying how it affects invertebrates and fish with our evidence suggesting that it is fuelling increases in both.’ The findings of the study were published in Proceedings of the Royal Society B. Artificial reefs and seagrass One of the biggest issues affecting seagrass is nutrient pollution, often from the release of human sewage. While the influx of nutrients can initially boost the growth of the meadows, it also promotes the growth of algae which reduces the amount of sunlight getting to the seagrass and harms it in the long run. Alongside fishing which causes levels of the fish faeces that fertilise the meadows to drop, it was thought that the combination of these two issues might work in unexpected ways to hinder the growth of seagrass. But the current study has revealed some surprising results. It has found that the productivity of seagrass in both disturbed and undisturbed meadows was increased by the presence of an artificial reef, while algae didn’t actually seem to pose an issue, even in areas where nutrient pollution was high. Mona Andskog, the PhD student who led the research, explains, ‘Artificial reefs built in seagrass create a positive feedback loop. They attract fish that use the reefs for shelter which, in turn, supply new nutrients from their faeces that fertilise the seagrass around the reef.’ ‘This increased primary production can increase invertebrate production by providing more food and shelter for invertebrates, which in turn provide more food for fishes.’ Experiments in Haiti, at some of the most fished sites included in the study, also showed that the artificial reefs were providing additional benefits to the fish. Large numbers of small fish were found at the site because of the difficulty in using nets around the reef, meaning that the overall biomass of fish was at times larger than in unfished areas measured elsewhere in the study. While artificial reefs present a promising option for tropical seagrasses, they’re likely to have a much more limited impact on temperate meadows. These waters already tend to have higher nutrient levels, meaning that any contribution the reef would made to overall growth would be small. The scientists now hope to explore how the placing of artificial reefs can affect seagrass ecosystems, as well as expanding their research to the Dominican Republic. ‘We will be testing how different configurations of artificial reef clusters can affect the production and fish community composition,’ Jacob says. ‘This includes the number of artificial reefs in each cluster, as well as their arrangement.’ ‘As with this research, we hope to simultaneously use the reefs to test fundamental questions about production in these highly impacted ecosystems as well as optimising the positive feedback that is initiated by the artificial reefs.’ More information: Mona A. Andskog et al, Seagrass production around artificial reefs is resistant to human stressors, Proceedings of the Royal Society B: Biological Sciences (2023). DOI: 10.1098/rspb.2023.0803 This story is republished courtesy of Natural History Museum. Read the original story here.
For approximately 3,000 years, generations of green sea turtles have returned to the same seagrass meadows to eat. This was discovered by Willemien de Kock, a historical ecologist at the University of Groningen, by combining modern data with archaeological findings. Sea turtles migrate between specific breeding places and eating places throughout their lives–this much was known. But the fact that this stretches over many generations highlights the importance of protecting seagrass meadows along the coasts of North Africa. The results were published in PNAS on July 17. When young green sea turtles hatch, their parents have already left for a long journey. The little turtles clumsily make their way off the beach into the ocean and, not yet able to navigate the long migration of their parents, float around for years. During this time, they are not very picky eaters, omnivores even. Then, at about five years of age, they swim to the same area where their parents went, to eat a herbivore’s diet of seagrass. Along the coasts of the eastern Mediterranean Sea, volunteers are active to protect the nests of the endangered green sea turtles. However, as Willemien de Kock explains, “We currently spend a lot of effort protecting the babies but not the place where they spend most of their time: the seagrass meadows.” And crucially, these seagrass meadows are suffering from the effects of the climate crisis. Analyzing sea turtle bones In the attic of the Groningen Institute of Archaeology at the University of Groningen, De Kock had access to boxes full of sea turtle remains from archaeological sites in the Mediterranean Sea area. The excavations were already done by her supervisor, Dr. Canan Çakırlar. “All I had to do was dig in some boxes,” De Kock says. By analyzing the bones, De Kock was able to distinguish two species within the collection of bones: the green sea turtle and the loggerhead turtle. De Kock was also able to identify what the sea turtles had been eating. This relied on a substance called bone collagen. By inspecting the bone collagen with a mass spectrometer, De Kock could detect what kind of plants the sea turtles must have eaten. “For instance,” De Kock explains, “one plant might contain more of the lighter carbon-12 than another plant, which contains more of the heavier carbon-13. Because carbon does not change when it is digested, we can detect what ratio of carbon is present in the bones and infer the diet from that.” Combining old and new Modern satellite tracking data from the University of Exeter then provided De Kock with information on the current traveling routes and destinations of sea turtles. Researchers from Exeter had also been taking tiny samples of sea turtles’ skins, which revealed similar dietary information as De Kock found in bones. De Kock was, therefore, able to draw conclusions, connecting diets of millennia ago to specific locations. She found that for approximately 3,000 years, generations of green sea turtles have been feeding on sea grass meadows along the coasts of Egypt and West Libya. The results for loggerhead turtles were less specific because they had a more varied diet. So, why is it relevant to know the eating habits of a species over many past generations? Because we collectively suffer from the shifting baseline syndrome: slow changes in a larger system, such as an animal population, go unnoticed because each generation of researchers redefines what the natural state was, as they saw it at the start of their careers. “Even long-term data goes back only about 100 years,” says De Kock. “But tracing back further in time using archaeological data allows us to better see human-induced effects on the environment. And it allows us to predict, a bit.” In fact, recent models have shown a high risk of widespread loss of seagrass in precisely these spots where green sea turtles have been going for millennia. This could be detrimental to the green sea turtle, precisely because of its high fidelity to these places. More information: de Kock, Willemien, Threatened North African seagrass meadows have supported green turtle populations for millennia, Proceedings of the National Academy of Sciences(2023). DOI: 10.1073/pnas.2220747120 Story provided by University of Groningen
