Seagrass in the Stour, Orwell and Blackwater 2020/21.
Abstract
This report presents the results of a comprehensive survey conducted in summer 2021 to assess the status of Zostera eelgrass populations in the Stour, Orwell and Blackwater estuaries in north Essex and Suffolk, UK. The survey utilized shore-walking and drone techniques to map the distribution and abundance of Zostera species, particularly focusing on Z. noltei and Z. marina. Results indicated a significant decline in eelgrass meadows throughout the 20th century, with new locations for Z. noltei identified in 2021. The majority of observed eelgrass patches were small in size, indicating high fragmentation. Eutrophication and encroachment by opportunistic macroalgae and grass species were identified as potential threats to eelgrass habitats. Restoration strategies, including reseeding or transplanting shoots, are proposed to mitigate these threats. Collaboration among global seagrass conservation organizations is emphasized as crucial for ensuring the future resilience of Z. noltei in the face of environmental changes.