||Oceanolica Acta (0399-1784) (Gauthier-Villars), 1997 , Vol. 20 , N. 2 , P. 399-419
|WOS© Times Cited
||metazoan, non-calanoid copepod, Oncaea, Levantine sea
||The abundance and vertical distribution of micrometazoans sampled with fine nets of 0.05 mm mesh size were studied in different regions of the Eastern Mediterranean Sea down to a maximum depth of 1850 m. Significant east-west differences in biomass, total metazoan abundance and/or species composition of non-calanoid copepods were not recorded. The vertical gradient for total plankton biomass and abundance of major taxa was more or less consistent, showing no secondary maximum at inter mediate water layers. The copepods were dominated by poecilostomatoids (genus Oncaea) which accounted for about 50 % of total copepod numbers in the water column. The greatest relative abundance of poecilostomatoids (up to 80 %) was found in the mesopelagic zone, at 100 m to 1050 m. In the epipelagic zone, calanoids were most numerous, however. In the bathypelagic zone below 1050 m depth, harpacticoids (Microsetella spp.) were next in abundance to poecilostomatoids. More than 56 non-calanoid species were recovered of which 28 belonged to the genus Oncaea. Dominant Oncaea species in the epi- and upper mesopelagic zone were O. zernovi, O. ivlevi and Oncaea sp. K. Below 450 m and down to the deepest stratum sampled Oncaea longipes and Oncaea sp. 1 were most abundant. No Oncaea species had its main population centre in the bathypelagic zone. The results are compared with published data on micrometazoans in other tropical oceans (e.g. Red Sea, Arabian Sea) and the absence of a true bathypelagic microcopepod fauna in the Eastern Mediterranean is discussed. Similar to the Red Sea, the dominance of individual species among non-calanoids appears to be less pronounced than that reported for calanoids in the meso- and upper bathypelagic zones of the Eastern Mediterranean.