Diversity and community structure of epibenthic invertebrates and fish in the North Sea

TLDR

North Sea benthic invertebrate and fish community structure is a key indicator of anthropogenic and environmental impacts, yet benthic fauna are not routinely monitored unlike fish stocks. The survey aimed to assess epibenthic and fish diversity and community structure and to examine their relationships with environmental factors such as commercial trawling disturbance. In 2000, five nations conducted a coordinated survey sampling epibenthic and fish fauna at 270 stations across the North Sea. Results showed lower epibenthic diversity in the southern North Sea but higher fish diversity there, with depth contours delineating community boundaries, southern abundance dominated by free‑living species, northern by sessile species, and a hybrid zone off Norfolk and Flamborough extending to Dogger Bank.

Abstract

The structure of North Sea benthic invertebrate and fish communities is an important indicator of anthropogenic and environmental impacts. Although North Sea fish stocks are monitored regularly, benthic fauna are not. Here, we report the results of a survey carried out in 2000, in which five nations sampled the epibenthic and fish fauna at 270 stations throughout the North Sea. The aim of the survey was to investigate the diversity and community structure of epibenthic and fish communities and to identify relationships with environmental factors, including the frequency of commercial otter and beam trawling disturbance. Epibenthic species diversity was lower in the southern North Sea than in central and northern areas. Fish, conversely, were more diverse in the south. The 50 m, 100 m and 200 m depth contours broadly defined the boundaries of benthic and fish communities. The abundance of epibenthos of the southern North Sea was dominated by free-living species, whilst north of the 50 m contour sessile species prevailed. A hybrid area, with sessile species typical of the north and free-living species characteristic of the south, was found off the Norfolk and Flamborough coast stretching towards the Dogger Bank.