On the physical oceanography of the Kattegat and Clyde Sea area, 1996-98, as background to ecophysiological studies on the planktonic crustacean, Meganyctiphanes norvegica (Euphausiacea)

The euphausiid. Meganyctiphanes norvegica (M. Sars), has an extremely wide distribution around the North Atlantic, from Canada to the Arctic to the western Mediterranean. It appears to be adaptable to life under quite different oceanographic conditions, yet no morphological features have been identified that distinguish any of the populations occurring in different areas between which exchange must be supposed to be restricted. The genetic, physiological, behavioural and ecological investigations that are being carried out on M. norvegica in the Kattegat, the Clyde Sea area and the Ligurian Sea (the EU MAST III PEP Project) in order to study its adaptability must be closely related to the physical environment within which the respective populations occur. This paper presents a summary of the hydrographic conditions found in the Kattegat and the Clyde Sea area in summer and in winter, during each research cruise, and places them in the context of current understanding of the hydrography in each area. An account of the hydrography of the Ligurian Sea is in preparation (Dallot et al., in preparation). The data will be used in the further analysis of genetic, physiological and behavioural adaptability of M. norvegica, and will be available for use as appropriate to supplement other hydrographic studies in the regions concerned.