Coastal roots: the history of seagrass in Northern Ireland

Abstract A considerable knowledge gap exists in relation to the presence and even existence of seagrass within Northern Ireland’s waters. Peer-reviewed publications on the historical ecology of seagrass are scarce and a collated timeline of references directly focusing on Northern Irish seagrasses does not exist. Recognising abiotic and biotic induced environmental change within key marine features such as seagrass is vital when attempting to measure the biodiversity and carbon sequestration services they provide. The research undertaken during this study identified three distinct periods within the archival records, which could be matched to the ecological history of seagrass in Northern Ireland. The first period (extensive and dense seagrass meadows from 1790 to 1880) was characterised by extensive seagrass meadows which were dense and healthy. The second period (degradation from 1880 to 1940) saw the beginnings of decline in seagrass from the 1790s, initially from anthropogenic influences and later from the seagrass wasting disease) and the final period (signs of recovery from 1940 to present day) showed small amounts of local regrowth of seagrass but at far reduced densities compared to the historical baseline described. These three defined periods all delivered varying degrees of anthropogenic stressors which determined the conservational health of seagrass in Northern Ireland. Seagrass habitats have become integral components in future-proofing the coastal marine environment against the effects of climate change and its associated impacts. Therefore, it is envisaged that the historical baseline that this manuscript provides will greatly benefit habitat managers in protecting, repairing, and restoring lost seagrass meadows.