The Vertical Distribution of Micro- and Small Mesozooplankton in the Central Red Sea

AbstractThe abundance and taxonomic composition of plankton sampled with nets of 0.1 mm mesh size were determined at the Atlantis II Deep, central Red Sea, in October and November 1980, from the surface to a depth of 1650 m. The fine mesh nets yielded three times as much total plankton biomass and thirty times the number of metazoan organisms compared to what was collected during earlier investigations using nets with a larger, 0.3 mm mesh size. The patterns of vertical distribution, determined by using the two different mesh sizes, were similar with respect to the gradients of plankton abundance but different with regard to the relative proportions of species and higher taxa. When the smaller metazoans were included by the use of fine mesh nets, cyclopoid copepodids became more numerous than the calanoid copepodids in all depth layers sampled, and their relative importance increased with depth. Between 200 m and 1050 m depth, over 50% of all copepodids belonged to the cyclopoid genus Oncaea. A review of ...