Abundance of pelagic chaetognaths in northwestern Persian Gulf

Abstract

The abundances and species compositions of chaetognaths were investigated on the northwestern coasts of the Persian Gulf in Khuzestan province (2004–2005). Highest mean chaetognath abundance was observed during the summer (324.7±97.6 indiv. m⁻³), while lowest values occurred during the winter (79.3±18.6 indiv. m⁻³). Six species were identified, Sagitta bedfordi, S. enflata, S. ferox, S. hexaptera, S. neglecta and Krohnitta pacifica. Sagitta ferox was most abundant. It represented 49.7% of total chaetognath numbers. Abundance variation throughout the year cycle seemed to be related to environmental factors. The correlation coefficients between abundance of chaetognaths and the water temperature were significantly positive but there was no significant relation for abundance and salinity. However, salinity values in the Persian Gulf are very high compared with other regions and perhaps pelagic chaetognaths species that inhabit this region are adapted to very high salinities of up to 45.