Neuston composition in central Arabian Sea

Abstract

Composition of neuston in the Arabian Sea (lat. 16-19ᵒN., long. 60-72ᵒ E) was studied. The standing stock ranged between 1.5 and 49.3 ml (100 m²)^-1. Copepoda was generally the dominant group, forming on average 50.5% of the total organisms. But at some stations where the biomass was high, aggregation of the mysid <i>Siriella gracilis</i> was observed. The copepods <i>Undinula vulgaris, Acrocalanus gibber, Bestiola similis, Euchaeta rimana, Paracalanus</i> spp, <i>Labidocera</i> spp, <i>Oncaea</i> spp and <i>Corycaeus</i> spp commonly occurred in the surface layer. Chaetognaths were dominated by Sagitta enflata and decapod Crustacea by <i>Lucifer</i> typus. Many other taxonomical groups were also present, but in small numbers. Significant variations were not observed in the biomass and the commonly occurring species of copepods between day and night. Surface temperature at the southwest leg of the study area was relatively low ( < 28 ᵒC) and incidentally recorded high biomass values.