The microcopepod fauna in the Gulf of Aqaba, northern Red Sea: species diversity and distribution of Oncaeidae (Poecilostomatoida)

Abstract

A total of 23 species and three groups of form variants of oncaeid copepods have been identified, which were collected in small mesh net samples taken along a transect from the northernmost Red Sea (>27°N) to the Gulf of Aqaba down to a maximum depth of 800 m. Two of the species were present only in the Red Sea main basin, but were not recorded in the Gulf. By comparing the present results with previously published data from the central and southern Red Sea a first assessment of the zoogeographical distribution of Oncaeidae in the entire Red Sea has been achieved. The species diversity of Oncaeidae in the Gulf of Aqaba appears to be considerably lower compared to the southern Red Sea, where 31 oncaeid species and four groups of form variants have been found. The observed latitudinal gradient in species numbers of Oncaeidae generally corresponds to the gradients observed for various other zooplankton taxa in the Red Sea. First data on the vertical distribution of oncaeid species in the Gulf are provided.