Effects of some physico-chemical parameters of water and substrate sediments on abundance and biomass of Streblospio gynobranchiata (Annelida, Spionidae) in the Southeast of Caspian Sea (Goharbaran)

This study was carried out in line with the Caspian Sea water transportation program to the central plateau on the Southeast shores of the Caspian Sea (Goharbaran region) since 2013-2014. Sampling was performed monthly and there were 8 stations at depths of 5, 10 and 15 meters in 2 transects. The purpose of this study was to investigate the relationships between some physico-chemical parameters of water and total organic matter, distribution, abundance and biomass of Streblospio gynobranchiata (Spionoidae) in the different depths. The results showed that the highest abundance and biomass were in the Eastern transect with mean 1437.1±269.17 ind.m-2 and 0.711±0.131 g.m-2, respectively. A positive correlation was found between the abundance and biomass of S. gynobranchiata with TOM and at 0.01 level, salinity and water temperature at 0.05 level based on Pearson correlation test. The abundance and biomass of S. gynobranchiatain different seasons was fluctuating, with the highest abundance 1550.08±185.22 ind.m-2 and 0.775±0.09 g.m-2 recorded in winter and in January, respectively .So there was a significant difference between the abundance and biomass in different months (p<0.05). This could be due to the approach to the period of water disruption following the seasonal changes and the creation of a bioturbation in the seabed and a deposit feeder species.