Long term changes of macrozoobenthos in the Arkona Basin (Baltic Sea)

In 2001–2004 extensive studies of the macrozoobenthos community within the German Arkona Basin were undertaken. The results with consideration of the habitat conditions prevailing in different depth zones are presented. By multidimensional scaling we distinguished two separate macrozoobenthos communities (global r = 0.758, p = 0.1), one predominant in a habitat with sandy sediment or gravel and stones at water depths < 35 m (8–11 psu) and the other preferring a muddy habitat with higher salinity (11–23 psu) at water depths > 35 m. Additionally, long-term changes in selected benthic species of the Arkona Basin are described by comparing the recent macrozoobenthic data with data sets of the last 80 years. Special emphasis was placed on the use of historical data as a tool of assessment of changes of macrozoobenthic communities with respect to different habitat conditions. While the distribution patterns of several species under investigation have changed between the different time periods, nevertheless, with few exceptions no consistent changes from the past to present days were observed. The species composition of the macrozoobenthic community in the shallower area was very similar during all time periods. Only in deeper waters did we find differences, which may be explained by past changes in hydrography (e.g. salinity, oxygen). In both depth ranges a 3–10-fold increase of abundance from the past to the present has been observed that might have been caused by eutrophication.