Temporal Irregularities in the Macrobenthic Community and Deep-Water Advection in Wismar Bay (Western Baltic Sea)

Wismar Bay is a shallow coastal embayment in the Western Baltic Sea which is polluted by various industries. Macrobenthos data collected between 1986–91 are examined for qualitative and quantitative changes attributable to oxygen depletion and the subsequent time needed for recovery. Regular oceanographic surveys since 1976 indicate one episode of oxygen deficiency, caused by deep-water intrusion into the study area. However, principal component analyses show that the benthic community alternated between periods of relative stability and sudden change at both of the deeper sites examined. Deep-water intrusions from outside the bay are documented twice followed by sudden changes in the benthic community, but similar events may also have occurred in other years. The benthos showed little resilience when impacted, and the changes in the benthic community during July–August are proposed to monitor the future influence of the deep-water intrusions.