Historical records reveal the antiquity of seafloor ecosystem transformation: a global view

Bottom trawling and dredging gears have devastating impacts upon vulnerable marine seafloor habitats, but the antiquity of their use means that the true magnitude of change is often obscured. Within Europe, bottom trawling and dredging started centuries ago, with no scientific oversight of the initial impacts of these gears to seafloor structure and functioning. We describe how historical records published over a period of >350 years were used to evidence historical transformation of Europe’s seafloor ecosystems. We uncovered the loss of at least 17,000km2 of native oyster reef, largely driven by the 19^th century intensification of trawling and dredging. The collapse of this once dominant coastal and shallow seafloor ecosystem occurred more than 100 years ago and points to a previously unreported restructuring and ‘flattening’ of European seafloor ecosystems. We will present the findings from this study and our collation of similar evidence from around the world to rewrite the known history of seafloor ecosystem transformation. In so doing we aim to alert the conservation and restoration communities to the magnitude of seafloor restructuring that has occurred, highlight the implications of this transformation for biodiversity, ecosystem service provision, and carbon storage, and subsequently raise ambitions for global restoration and management.