The effects of fluctuations in North Sea flows on zooplankton abundance

Abstract

Time series of annual mean zooplankton abundance observed by the Continuous Plankton Recorder Survey in the North Sea during the last three decades are compared with transports from a depth-averaged storm-surge model by means of multiple regression analysis. In the northern areas, more than half the variance of Calanus finmarchicus can be accounted for by the winter flows. There are no statistically significant relationships in other North Sea areas or by using the flows from other seasons. This is consistent with the accepted view that this copepod overwinters in the North Atlantic and enters the North Sea in the early spring. The model flows are strongly related to the strength of the North Atlantic Oscillation (NAO), which may explain the recently reported association of C.finmarchicus with the NAO. Other species do not exhibit statistically significant relationships with any of the model flows.