Macrofauna standing stock of the Dogger Bank. A comparison: II. 1951–1952 versus 1985–1987 are changes in the community of the northeastern part of the Dogger Bank due to environmental changes?

Abstract

During April/May 1985–1987 some of Ursin's ( Ursin, 1960) stations on the Dogger Bank from April/May 1951–1952 were revisited. This paper concentrates on results from the ‘Tail End’, the northeastern part of the Dogger Bank. The polychaete species Ophelia borealis and Goniada maculata, which were dominant species in 1951–1952, showed similar distributions in 1985–1987 on the whole of the Dogger Bank. Changes in the macrofauna distribution are obvious in the increase of opportunistic small polychaete species like Spiophanes bombyx, Scoloplos armiger and Magelona spp. In 1985–1987 these species occurred in high individual numbers per m 2 all over the Dogger Bank in contrast to 1951–1952, when they were found only in few individuals. Extensive patches of the bivalve species Spisula subtruncata discovered at the northeastern border of the Dogger Bank in the fifties were not found. Only small, fast-growing species like Abra prismatica, Tellina fabula and Montacuta bidentata occurred in high individual numbers per m 2. In 1987 the total biomass shows a reduction of about 30% in the area compared with 1950–1954 Some hypotheses are given to explain the changes in macrofauna distribution on the Dogger Bank between 1950–1954 and 1985–1987, taking into account the increasing eutrophication and pollution.