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 we stern Mediterranean. It appears to be adaptable to life under quite differe nt oceanographic conditions, yet no morphological features have been identi fied that distinguish any of the populations occurring in different areas b etween which exchange must be supposed to be restricted. The genetic, physi ological, behavioural and ecological investigations that are being carried out on M. norvegica in the Kattegat, the Clyde Sea area and the Ligurian Se a (the EU MAST III PEP Project) in order to study its adaptability must be closely related to the physical environment within which the respective pop ulations occur. This paper presents a summary of the hydrographic condition s found in the Kattegat and the Clyde Sea area in summer and in winter, dur ing each research cruise, and places them in the context of current underst anding of the hydrography in each area. An account of the hydrography of th e Ligurian Sea is in preparation (Dallot et al., in preparation). The data will be used in the further analysis of genetic, physiological and behaviou ral adaptability of M. norvegica, and will be available for use as appropri ate to supplement other hydrographic studies in the regions concerned.