Influence of upwelling on the chaetognath community along the Southeastern Arabian Sea

Community structure and distribution of chaetognaths were investigated along the upwelled and non-upwelled waters of Southeastern Arabian Sea (SEAS) from the coastal, shelf and open ocean regions. With the onset of monsoon, intense upwelling along the southern part of SEAS (8° 28′ N) and a weak coastal upwelling along the northern counterpart (15° 30′ N) was evident. Zooplankton biomass was observed to be high in the upwelled waters with the dominance of copepods. Chaetognaths were also observed in significant numbers all along the SEAS, however maximum numerical abundance was observed in the southern upwelled waters. Chaetognaths belonging to 10 genera were identified of which genus Flaccisagitta (54%) made the most dominant group along the entire study area followed, in order of abundance, by Serratosagitta (20%), Mesosagitta (18.2%), Sagitta (12.3%), Ferosagitta (11%) and Krohnitta (6.4%). Flaccisagitta were observed to be abundant in the upwelled waters along with Pterosagitta, Serratosagitta, Sagitta, Krohnitta and Ferosagitta whereas genus Mesosagitta dominated the non-upwelled waters of northern transects.