Response of macrozoobenthos to a temporal lowering of chlorinity: a large-scale field experiment in the Dutch delta area

Since construction of a dam and sluices on the Krammer-Volkerak estuary in 1969, the salinity has increased and in addition to the existing brackish water fauna, marine organisms have begun to colonize the area. For an experimental period during the winter of 1979-80, freshwater discharge through the sluices was doubled. Before and after sampling of the macrozoobenthos revealed that species diversity decreased immediately after the period of higher discharges, though later a recovery was noted. It was concluded that a reduction in salinity during the winter would have few serious effects on the habitat, and mussels (Mytilus edulis) would be unaffected.