The response of Calanus finmarchicus populations to climate variability in the Northwest Atlantic:: basin-scale forcing associated with the North Atlantic Oscillation

The North Atlantic Oscillation (NAO) is associated with decadal-scale forcing of climate and physical oceanography throughout the North Atlantic. Oceanographers have recently established correlations between the NAG and various processes at work in the shelf ecosystems of the NE Atlantic, correlations that have led them to suggest several hypotheses explaining the mechanistic basis of ecosystem and population responses to the NAG. Here, we incorporate these ideas into a new. conceptual framework for interpreting the responses of shelf ecosystems to climate variability on both sides of the North Atlantic. This conceptual framework, contrasting the relative importance of internal ecological dynamics versus advective exchange processes, is used to examine the trans-Atlantic responses of Calanus finmarchicus populations to the NAG. We conclude by proposing an NAG-based explanation for the trends in C. finmarchicus abundance observed from 1961 to 1989 on the NW Atlantic Shelf. (C) 2000 International Council for the Exploration of the Sea.