SHORT-TERM VARIATIONS OF THE ZOOPLANKTON COMMUNITY NEAR THE STRAITS-OF-MESSINA (NORTH-EASTERN SICILY) - RELATIONSHIPS WITH THE HYDRODYNAMICREGIME

Zooplankton samples were collected near the Straits of Messina over tw o 24-h periods in May 1988 and January 1989. Ln this area, the complex system of currents which circulate through the Straits still affects both biotic and hydrological factors even near the shore. Copepoda, Cl adocera, Chaetognatha and Appendicularia together with some meroplankt onic taxa make up the zooplankton assemblage collected during the two periods. The community structure changes greatly in terms of biomass a nd density during the 24-h cycle, and in terms of species composition between the two sampling months. The variability of biomass and densit y could be ascribed to the effect of the special current system in the area, whereas variations in species composition could be related to t he seasonality demonstrated by the zooplankton community. These factor s combined are responsible for the peculiar condition described in the paper. (C) 1996 Academic Press Limited