Long-term changes in macrofaunal communities off Norderney (East Frisia, Germany) in relation to climate variability

Abstract

Macrofaunal samples were collected seasonally from 1978 to 1995 in the subtidal zone off Norderney, one of the East Frisian barrier islands. Samples were taken with a 0.2 m2 van Veen grab at 5 sites with water depths of 10 to 20 m. Interannual variability in biomass, abundance and species number of the biota were related to interannual climate variability using multivariate regression models. Changes in the biota were described in relation to human impact and seasonal and long-term meteorological variability. Our analyses suggest that macrofaunal communities are severely affected by cold winters, whereas storms and hot summers have no impact on the communities. It appears that mild meteorological conditions, probably acting in conjunction with eutrophication, have resulted in an increase in total biomass since 1989. A multivariate model found the following strong relationship: abundance, species number and (less clear) biomass in the second quarter are correlated with the North Atlantic Oscillation (NAO). The mediator between the NAO and benthos is probably the sea-surface temperature (SST) in late winter and early spring. On the basis of our results, we suggest that most of the interannual variability in macrozoobenthos can be explained by climate variability.