Searching for Shetland’s lost seagrass: establishing the baseline distribution and abundance of seagrass in the Shetland Islands

Seagrass habitats are among the most productive and valuable marine ecosystems—supporting biodiversity, protecting coastlines, and capturing carbon. However, these habitats are now vulnerable, following widespread loss across the UK. This study assessed the historical and current distribution of seagrass beds in the Shetland Islands, focusing on subtidal eelgrass beds (Zostera marina). Analysis of historical records from 1837 to 2020 identified 73 instances of Z. marina across 12 sites. Small Unmanned Aircraft Systems (UASs or drones) were employed to survey these sites, with aerial imagery analysed to identify subtidal marine features. These features were ground-truthed via community-led snorkel and paddleboard surveys. The presence of extant Z. marina beds were confirmed only in Whiteness Voe and Weisdale Voe. Across these two sites, 14 eelgrass beds were identified with an estimated total area of 1.62 hectares. The Whiteness Voe beds were dense and in good condition, while the Weisdale Voe bed was sparser. No evidence of Z. marina was found at the other 10 sites, indicating continued habitat decline since the 1990s. The study highlights the utility of UASs in mapping remote seagrass habitats and underscores the importance of preserving detailed historic records to guide future conservation and restoration efforts.