Would you like to view our US Site?

Executive Summary:

Located at the centre of the southern North Sea, Brown Bank (also known as Brown Ridge, and as Bruine Bank in Dutch) is a ridge formed by a series of large-scale sandbanks in Dutch and UK waters. It is a recognised area of ecological interest, due mainly to the high abundance of cetaceans and seabirds in the area. To date, however, Brown Bank has been granted very limited protection. The UK side is protected for a single species (harbour porpoise), within the Southern North Sea MPA. No protection is in place for the Dutch side, although it qualifies for inclusion in the Natura 2000 network due to the high numbers of seabirds that it supports, particularly common guillemot and razorbill. Despite the known importance of Brown Bank for marine life, relatively less attention has been paid to its benthic biodiversity. To address this information gap, Oceana carried out two research surveys in 2016 and 2017, to gather information about benthic species and communities. Surveys were carried out via a remotely operated vehicle and infaunal grab sampling, aided by a multibeam echosounder and side-scan sonar. In total, 204 taxa were identified. These taxa included nine priority species for conservation, and a range of commercially fished species, including fishes for which Brown Bank provides spawning or nursery habitat. The most noteworthy discovery was the presence of biogenic reefs formed by ross worm (Sabellaria spinulosa), a sedimentary polychaete. These reefs covered a total area of 1023 m2 on the Dutch side of Brown Bank, and hosted a variety of associated species, including various crabs, common dragonet, and lesser spotted dogfish. Such biogenic reefs have nearly disappeared from Dutch waters, and ross worm reefs were previously thought to have been long-extinct in the area. On the basis of this important discovery, Oceana recommends that Dutch waters of Brown Bank be protected immediately, in order to safeguard the fragile reefs. Such measures to protect and recover the reefs are required under both EU and international conservation frameworks. Critically, anthropogenic threats to the seabed must be minimised – particularly bottom fishing, which is intensive in the area. In parallel with protecting the newly discovered reefs, Oceana urges the Netherlands and UK governments to carry out comprehensive benthic habitat mapping of Brown Bank, to identify any additional ross worm reefs and to assess their condition and extent.

Download the Report