A contribution to the study of the surface and deep zooplankton in the Strait of Sicily

Abstract

Analysis of 34 hauls of plankton in the Strait of Sicily, from 5 to 21 May 1970, enabled us to make a systematic, quantitative and ecological study of all zooplankton systems present. Vertical fishing was performed with a standard IlAIl type closing net and sampling of the zooplankton was carried out by the techniques already utilized in 1970 and 1971. Species of Atlantic origin were found throughout the Strait but they were fished in greater number in those places where the influence of the Atlantic water mass was most felt. It was established that the bathygeography of the Strait, as well as the local circulation within the water mass, causes bathymetrical inversions among the deep species with some interference of diurnal migrations. The stenothermia of certain s pecies ] particularly the Copepoda, Chaetognatha, Euphaus lids and Thaliacea was demonstrated and confirmed.