The FANNS programme took place between 2024 and 2026. One of the focuses within the programme was on improving the natural environment through a series of restoration trials across multiple Special Areas of Conservation in South and West Wales. These trials aimed to establish the most effective methods of planting seagrass out into the field.
Carmarthen Bay and Estuaries SAC
Following site assessments and stakeholder engagement, Ellis Bay in Llanelli was identified as the site for the restoration trials within the Carmarthen Bay and Estuaries SAC.
Zostera noltei was identified as the most appropriate species for restoration at this site due to the estuary’s intertidal nature and sediment characteristics.
In May 2024, the Project Seagrass team were joined in the field by Carmarthen Bay & Estuaries European Marine Site Officer Judith Oakley and Carmarthen Conservation Coordinator Paul Aubrey. 75 Zostera noltei cores were transplanted from a healthy donor meadow near Llanelli to the Llanelli trial site using the plug method.
Monitoring later that summer in August 2024 demonstrated positive results with a significant percentage (40 %) increase in growth from the initial core size, indicating strong early establishment and expansion. These results were highly encouraging, suggesting that Llanelli site conditions were suitable for Zostera noltei transplant success.
Building on the success of the 2024 trial, further planting took place in May 2025. 72 Zostera noltei transplants were collected from the donor meadow. The 2025 planting plots were located further towards the foreshore to enable the team to explore planting into alternative sediment types and to more closely reflect the distribution of the natural meadow on the western side of the Bay.
Monitoring of both the 2024 and 2025 planting efforts took place in August 2025 with the 2025 planting plots evidencing significant loss. Shortly after transplanting, the site experienced a period of elevated temperatures followed by storm events. Sediment redistribution around the plots was evident during the team’s monitoring which may have destabilised newly planted cores, while heat stress would have compounded physiological stress following transplantation.
The previous years planting survival was more varied but generally stronger with plots located closer to the low shore within muddier sediments showing higher survival rates and successful expansion, in some cases demonstrating up to 35% growth relative to the original core size. Plots positioned closer to the foreshore experienced comparatively greater loss.
The contrast between 2024 and 2025 results highlights the importance of sediment stability and micro-site selection in transplant success.
Given the positive expansion observed in 2024, there is a strong case for scaling up transplant effort within suitable sediment areas across the bay with plans for further transplant trials in Llanelli to build upon this learning.
Severn Estuary SAC
Within the Severn Estuary SAC, Butetown foreshore in Cardiff was selected as the site for planting trials. This location was identified based on Habitat Suitability Modelling, desk-based reviews, and in-field surveys which revealed the presence of three small, isolated Zostera marina seagrass patches at the site.
In May 2024, the Project Seagrass team planted 60,000 Zostera marina seagrass seeds at the Cardiff site, using the Direct Injection Seeding (DIS) planting method developed by The Fieldwork Company. Monitoring later in the summer revealed no germination success from these planting efforts which led to a smaller repeat trial in 2025. A further 3,200 seeds were planted using the DIS method, this time adopting a Seagrass Hug configuration. The Seagrass Hug method has been developed by Anouska Mendzil, Senior Science Officer at Project Seagrass and Swansea University, and aims to determine whether surrounding seed plots with more established seagrass transplants provides protection for emerging seeds in restoration practices. This trial was undertaken in collaboration with the Seagrass Consortium.
A total of 525 seagrass transplants were planted at the Cardiff site as part of the trials with varying degrees of success. 75 Zostera noltii transplants planted in 2024 initially showed signs of survival which would have established the presence of an additional seagrass species at the site, creating the potential for future development of a mixed meadow. However, by 2025 these transplants had been lost. 450 Zostera marina further transplants from the Project Seagrass Nursery were planted out in 2025, using coir pots of varying sizes and a mixture of plants that had been hardened outdoors in ponds at the Seagrass Nursery, while the remainder were grown inside the polytunnel. These trials allowed the team to undertake a comparison of transplant establishment by container type and nursery conditioning to inform future restoration approaches. Whilst monitoring highlighted that there had been significant loss from the initial number of transplants planted, several shoots persisted across the different planting methods. However, remaining shoots were generally found to be stressed and silt-covered, indicating environmental pressures at the site.
Throughout the programme of work, environmental data was gathered at the site to allow the team to monitor site conditions which might have impacted the success of the planting. Several environmental factors are likely to have influenced the restoration success at this particular site including elevated wave energy, high pool temperatures, silt smothering within intertidal pools, high epiphytic load, and the potential that the Zostera marina nursery stock used (from a source population in North Wales) may not represent the optimal ecotype for this environment.
The Cardiff trials demonstrated that the Direct Injection Seeding method is not suitable for restoration at Cardiff under current site conditions. Transplant-based approaches showed limited but measurable persistence, with container type influencing relative survival. However, overall survival rates remain low, suggesting that environmental constraints may outweigh methodological refinements at the current scale of intervention.
Further trials using transplants from a seagrass meadow in Stolford will allow the team to trial whether plants with a more comparable ecotype show higher levels of success at the site.
Pembrokeshire Marine SAC
Dale Bay within Pembrokeshire SAC, continued to serve as a primary restoration site as part of the FANNS programme. Restoration activity in Dale focused on seasonality trials and planting method comparisons.
Seasonality trials
In autumn 2024, 150 Zostera marina transplants were planted using the metallic pin method. This trial was replicated in May 2025 with the support of volunteer freedivers from the local area. This marked the first time freedivers have been engaged in volunteer-based subtidal seagrass transplanting in the UK.
Monitoring in October 2025 highlighted that the spring 2025 transplants showed higher average shoot density than the autumn 2024 transplants, indicating stronger performance from spring planting relative to autumn planting at this site.
Planting medium trials
In March 2025, 30 volunteers joined the Project Seagrass team for a Spot and Plant event in Dale Bay. This involved seagrass planting to compare the success of different planting mediums.
150 sediment-intact hemp bags were used as part of the trial alongside 150 bare-root shoots secured with bamboo mossing pins. Whilst monitoring in May 2025 showed that both methods had experienced some loss, biodiversity observations made by the team at this early stage included crabs, flatfish and egg deposition on seagrass leaves, indicating rapid ecological use of the plots. Further monitoring in October 2025, saw both planting approaches demonstrating substantial growth with increased in plant length, and increased shoot number by approximately 30% across both treatments. Two dense seagrass plots are now established within Dale Bay as a result of these trials, contributing to the expanding mosaic of restored patches.
A further Spot and Plant event took place with the support of local volunteers and Swansea University students in March 2026. A further 180 seagrass transplants and 40,000 seeds were planted with ongoing monitoring planned to determine the success of these most recent planting efforts.
The FANNS programme was made possible thanks to the support of the Nature Networks Programme, being delivered by The National Lottery Heritage Fund on behalf of Welsh Government. Project Seagrass is grateful to our funders, partners, and members of the community for making this work possible.
