MCCIP ARC Science Review 2010-11:Shallow and shelf subtidal habitats and ecology

There is evidence that climatic processes influence species abundance and community composition in soft-sediment habitats in the North Sea. There is no obvious signal of warming effects in sediments in southern and south-western areas where changes would be most expected. However, changes in crustacean abundance in some locations and the occurrence of previously undocumented species in others (e.g. brittle star Amphiura incana and shrimp Athanas nitescens) suggest some degree of climate-influence. Hard-substrate habitats in southern and south-westerly waters appear to be affected, with disease outbreaks in seafans, changes in algae distribution and abundance and the appearance and increased occurrence of a previously unrecorded warm-water barnacle all linked to increased seawater temperatures. Climate change is likely to impact the benthos in future. The changes documented in soft-sediment communities are expected to continue, and probably escalate, in response to the cumulative effects of seawater warming and ocean acidification. Species forming cold-water coral reefs and maerl beds may experience shifts in distribution as a result of intolerance to altered seawater temperature and chemistry, with knock-on effects on community composition and function. Future impacts on these habitats are likely to have socio-economic ramifications, as cold-water coral reefs and maerl beds are protected under European legislation and soft-sediment communities are an important food resource for commercial fish. There are knowledge-gaps in a number of areas. We are currently unable to fully assess the scale of benthic species and community responses in relation to climate change, understand links between impacts in benthic and pelagic systems or model future species distributions. An appropriate benthic monitoring and assessment programme, coupled with continued involvement in international initiatives, is essential for characterising climate impacts in UK benthos