Project Seagrass have an ongoing voluntary seagrass survey in the Isles of Scilly which Natural England part fund. The purpose of this project is to continue to collect data to contribute to the ongoing condition assessment of the seagrass beds which are a feature of the Isles of Scilly Complex Special Area of Conservation (SAC).
In this report, we present novel data from an ongoing, spatially replicated, annual study of a comparatively un-impacted, temperate eelgrass habitat, based around the Isles of Scilly, UK. Five sites were assessed: Broad Ledges Tresco, Higher Town Bay, Little Arthur, Old Grimsby Harbour, and West Broad Ledges. Metrics include eelgrass (Zostera marina) shoot density, number of leaves per shoot, maximum shoot length, as well as semi-quantitative recording of signs of wasting disease and epiphyte cover on a leaf-by-leaf basis. Findings from this year’s survey, as well as their place in continuous time series from 1996, are presented and analysed. This represents 26 years of continuous annual monitoring around the Isles of Scilly.
The synthesis of these findings indicates concerning declines in eelgrass at Old Grimsby Harbour since the start of monitoring in 1996 and with no obvious change in downward trajectory since SAC designation in 2005. However, analysis of long-term trends at different scales point to patch creation and loss, rather than within-patch dynamics, as the key processes to focus on to identify causes of decline. Elsewhere across our sampling locations within the Isles of Scilly SAC, eelgrass remains in good condition.