Les poissons et les courants

The distribution of marine species according to climatic environmental conditions has been of interest to biologist for a long time. Biologists distinguish fauna from cold regions from fauna of temperate regions and have geographically classified them into provinces. In North Atlantic waters, from north to south, are recognised the following provinces: the Arctic Province that stretches from the North Pole to the Barents Sea; a Boreal province that covers the shelves of Scandinavia and the British Isles; the Atlantic-Mauritanian province (temperate) that includes the Lusitanian province and the Mauritanian province between which may be intercalated a rather distinct Mediterranean domain; finally, more to the south, a Guinean province (tropical) that straddles the equator. The distribution of these provinces is nearly symmetrical in the southern hemisphere from Antarctica to the equator. In a fundamental study on zoogeography, Ekman (1953) addressed the distribution of fauna according to the provinces. These major divisions, which are particularly applicable in the neritic zone that spans the continental shelf, often correspond somewhat to an analogous distribution of species on either side of the equator. Its has been long known that in the Arctic and Antarctic regions with comparable climatic conditions, similar forms have been found, particularly in species from families Zoarcidae, Lophiidae and Gadidae. Bipolarity can be explained by progressive adaptation of these fishes to the deep, cold sea under warm surface waters whose layers are quite thick at the equator but thin out in higher latitudes....