Population abundance and species composition of chaetognaths in the Bombay harbour-Thana and Bassein creek estuarine complex

Abstract

Detailed study on the abundance, distribution and species composition of chaetognaths from the Bombay harbour-Thana and Bassein creek estuarine complex was carried out from October 1985 to September 1986. Percentage contribution of chaetognaths to total zooplankton biomass varied from as low as 0.01 to as high as 25.78%. Unlike earlier studies in the same area, the present study recorded the presence of only 4 species viz. Sagitta bedoti, S. enflata and S. bedoti being the most common, dominant and tolerant of them. Total absence of S. eflata in the interior stations receiving large quantities of sewage and industrial effluents signifies a highly sensitive nature of this species. The present study shows a general decrease in the species diversity but an overall increase in the population density of chaetognaths. S. bedoti and S. oceania dominated the complex indicating adaptation of these hardy species to the prevailing water quality