Essai de classement bathymetrique des formes zooplanctoniques en mediterranee

Research on the vertical distribution of zooplankton in the western Mediterranean is still rare. With the exception of the Thor's campaigns covering the whole of the two basins, vertical fishing has long remained rare and localised. Nonetheless, for some ten years now the practise has been growing, from combined deep harvests to hydrological reports. It is in this context that the Institute of Maritime Fishing carried out, with the oceanographic ships President Theodore Tissier in 1958 and Thalassa in 1961 and 1963, several series (respectively K, N, and P) of vertical samples, at various levels throughout the western basin, but most especially in the Ligurian-Provençal channel and in the central sector (figure 1) that are the subject of this paper. We will find in the previous research work of M.L. FURNESTIN and ARNAUD (1962) and RAMPAL (1967) the complete characteristics of the 24 stations, corresponding to as many instances of surface fishing and 68 deep samples. Although the harvesting devices used during the three campaigns are different (Schmidt-type net in 1958 and closing Discovery in 1961 and 1963), it is possible to make qualitative, if not quantitative, comparisons of the results. Some results have already been published based on this material, or are about to be published; here are the details: President Theodore Tissier campaign, 27 September- 8 October 1958: Copepods (MAZZA, 1967), Pteropods (RAMPAL, 1967) and Euphausiacea (CASANOVA-SOULIER, soon to be published); Thalassa campaign, 7-12 January 1961: Copepods (MAZZA, 1962), Chaetognaths (M.L. FURNESTIN, 1962), Euphausiacea (SOULIER, 1963), Pteropods (RAMPAL, 1966), Cladoceres and Thaliacea (CASANOVA, 1964 and 1966); Thalassa campaign, 17 and 18 November 1963: Copepods (MAZZA, 1967), Pteropods (RAMPAL, 1967) and Euphausiacea (CASANOVA-SOULIER, soon to be published). This attempt at bathymetric classification relies on the full set of this research as well as on my personal observations focusing on the following groups: Jellyfish, Siphonophores, Cephalopods, Ostracoda, Mysidacea, Amphipods, Decapod Crustaceans, Chaetognaths, Appendiculates, Thaliacea and Fish.