Trends in biomass, density and diversity of North Sea macrofauna

Abstract

Total biomass and biomass of large taxonomic groups (polychaetes, molluscs, crustaceans, echinoderms) and species diversity of the macrofauna were determined for almost 200 North Sea stations sampled synoptically by seven vessels during Spring 1986 and for 120 additional stations sampled in earlier years by the Marine Laboratory in Aberdeen. There exists a clear and significant decreasing trend in biomass with latitude, both in total biomass and for the different taxonomic groups. Apart from latitude, sediment composition and chlorophyll a content of the sediment also infuence total biomass and biomass of most groups significantly. Biomass increases consistently in finer sediments and sediments with a higher chlorophyll a content. The same trends are found for the results within laboratories. Some interaction exists, indicating weak laboratory and zonal effects. Diversity, as measured by Hill's diversity index N, = (exp H') shows a clear and significant trend with latitude. Towards the north of the North Sea diversity increases considerably. The trend is also found for laboratories separately and is everywhere equally strong. Also longitude and depth show an effect on diversity. Sediment variables have no clear influence on diversity. Other diversity measures show the same trend but are more variable than N,. Total density tends to increase towards the north, but sediment related variables have a larger influence. Mean individual weight becomes considerably smaller towards the northern part of the North Sea.

Benthic macrofauna communities of the submersed Pleistocene Elbe valley in the southern North Sea

“…A negative correlation of biomass with latitude was found by Heip et al (1992), which holds true also for the macrozoobenthic community of the Pleistocene Elbe valley. Duineveld et al (1991) stated a more complex image of biomass distribution; nevertheless, they also found an increased biomass in the area of the island of Helgoland.…”

“…Later studies aimed at creating detailed pictures of the biotic community structure of the seaXoor and its connections to biotopes, pollutions, and nature conservation (e.g. Caspers 1939;Stripp 1969;Salzwedel et al 1985;Duineveld et al 1991;Heip et al 1992;Künitzer et al 1992;Rachor and Nehmer 2003). Gear and methods employed have constantly been improved, and with the introduction of computers the possibility arose to analyse vast amounts of data from exhaustive surveys with statistical methods (Salzwedel et al 1985).…”

Regional patterns of continental shelf polychaete diversity: examples for the North Sea, English Channel, Irish Sea and Outer Bristol Channel areas

“…The decrease in diversity with increasing latitude and depth is a well-documented pattern that has been described for some marine groups such as copepods, gastropods and bivalves (Rex et al 1993;Rombouts et al 2009), although an increasing number of researchers have shown that this pattern is not as universal as it was thought to be (Clarke 1992;Heip et al 1992;Roy et al 2000;Kindlmann et al 2007;Rees et al 2007). Dauvin et al (1994), using a smaller database, had already shown this for polychaetes of the northeastern Atlantic.…”

“…This may also be related to not only the reduced salinities there, but also the high climatic and hydrological variability and disturbing human influences, including pollution and eutrophication (Rees et al 2007). According to Heip et al (1992), the effect of longitude on diversity possibly shows the importance of current patterns on species distribution. These seemingly west-to-east trends shown with univariate methods could indicate that the eastern North Sea is generally impoverished in diversity.…”

Biogeomorphology of coastal seas

“…Given the high biodiversity in the subtidal area (e.g. Heip et al, 1992), insight is needed in the relation between geomorphodynamic processes and biota for the conservation and management of the biodiversity in the coastal zone. Moreover, these benthic organisms are known to influence their habitat, resulting in biogeomorphological interactions.…”