Assessing the state of marine (benthic) biodiversity in the Northeast Atlantic

International audienceThe Northeast Atlantic, a highly productive maritime area, has been exposed to a wide range of direct human pressures, such as fishing, shipping, coastal development, pollution, and non-indigenous species (NIS) introductions, in addition to anthropogenically-driven global climate change. Nonetheless, this regional sea supports a high diversity of species and habitats, whose functioning provides a variety of ecosystem services, essential for human welfare. In 2017, OSPAR, the Northeast Atlantic Regional Seas Commission, delivered an assessment of marine biodiversity for the Northeast Atlantic, including that of benthic temperate reef communities. This assessment examined biodiversity indicators separately to identify changes in Northeast Atlantic biodiversity. Here, we expand on this work and for the first time, a semi-quantitative approach is applied to evaluate holistically the state of Northeast Atlantic benthic marine biodiversity, including benthic-pelagic coupling and xeno-biodiversity (i.e. NIS). Our analysis reveals widespread degradation in marine benthic ecosystems and biodiversity, much of which is likely the result of cumulative effects of multiple human activities, such as overexploitation, the introduction of NIS, and climate change. The status of many indicators, however, is uncertain due to gaps in data, unclear pressure-state relationships, and the non-linear influence of some pressures on biodiversity indicators. Lessons learned from this regional assessment will drive future improvement methods to progress towards a better integrated assessment of wide-scale marine benthic ecosystems Synergies between science and policy throughout the assessment process were identified as a critical enabler to delivering holistic and scientifically-robust biodiversity assessments