Jersey seagrass report

This report reviews seagrass biology, ecology, and global status before focusing on seagrass meadows around Jersey, Channel Islands, highlighting their distribution, biodiversity, health, and carbon storage capacity. Seagrass ecosystems support marine biodiversity, coastal protection, and climate change mitigation. However, Jersey’s seagrass habitats have shown significant changes in recent years, reflecting both their ecological importance and the pressures they face. Mapping efforts using aerial photographs reveal seagrass distribution and extent along Jersey’s coast, notably in St Aubin’s Bay, Grouville Bay, and St Catherine’s Bay, and offshore at Les Minquiers and Les Écréhous. Historical and current data reviewed in this report reveal both expansion and contraction of seagrass meadows over different time periods. Jersey’s seagrass meadows are critical for biodiversity, providing habitats for commercially important species and contributing to blue carbon. However, the health of these meadows varies, with some areas showing signs of stress due to pollution, declining water quality, and coastal activities. Many research studies have been carried out on Jersey’s seagrass habitats over the past couple of decades with various focuses including but not limited to:
• Biodiversity
• Distribution and extent
• Impact of pollution
• Fisheries value
• Carbon storage
This report summarises all the local research on seagrass and brings together the key findings, identifying critical knowledge gaps and proposing directions for future research. This report highlights the recent expansion of seagrass meadows, likely due to natural regeneration and local conservation efforts. While this expansion is promising, further research is needed to understand the impact of human activities–such as coastal development, anchoring, and pollution–on these habitats. The future health and extent of Jersey’s seagrass meadows remains uncertain. A clearer understanding of what constitutes a “healthy” seagrass meadow in Jersey is essential for effective management and conservation. While biodiversity assessments show that seagrass supports diverse species, there is limited knowledge of the trophic networks and the long-term changes in species composition, especially for populations dependent on seagrass for critical life stages. Additionally, while current data highlights the significant role of Jersey’s seagrass beds as carbon sinks, more research is
needed to assess their carbon sequestration potential fully. This report synthesises current research on Jersey’s seagrass, emphasising the need to protect these habitats to enhance their contribution to biodiversity, fisheries, and climate resilience. It stresses the
importance of integrating seagrass conservation into broader marine spatial planning. Despite protections from mobile fishing gears, areas of high human activity overlap with these key habitats. Improved management of water quality, anchoring, and development is necessary to sustain seagrass expansion and long-term ecosystem health. By addressing knowledge gaps through research and adaptive management, Jersey can continue to protect and expand its seagrass meadows, which provide vital ecosystem services.