Investigation the presence of Hediste diversicolor in the sediments of Southern coasts of Caspian Sea (۲۰۱۹)

The purpose of this study was to investigate of distribution, density and biomass Hediste diversicolor of substrate sediments on the Southern coasts of the Caspian Sea (Bandar Torkman, Amirabad and Babolsar), were evaluated using a Van Veen Grab in triplicates during ۲ seasons in ۲۰۱۹. Sampling was done in spring and summer and ۶ stations at depths of ۵, ۱۰ and ۳۰ meters of the ۳ transects. In spring, the results showed that the highest density and biomass in Bandar Torkman (respectively) ۶۴±۱۹.۶۲ ind.m۲ and ۰.۶۲۸±۰.۱۸ g.m۲. Also showed that the mean (±SE) of density and biomass were in the Amirabad and Babolsar transect (respectively) ۳۰±۱۰ ind.m۲ and ۰.۲۴۲±۰.۱۲۲ g.m۲, ۳۵±۱۲.۵۸ ind.m۲ and ۰.۲۸۶±۰.۰۹۶ g.m۲ in spring. So, there was a significant difference between the density and biomass in different transects (p<۰.۰۵) in spring. According to this study, in summer, the highest density and biomass in Bandar Torkman transect with mean ۸۹±۲۹.۸۳ ind.m۲ and ۰.۰۷۶±۰.۰۲۱ g.m۲ recorded. Also showed that the mean (±SE) of density and biomass were in the Amirabad and Babolsar transect respectively) ۴۰±۱۲.۵۸ ind.m۲ and ۰.۰۵۲±۰.۰۱۵ g.m۲, ۴۰±۷.۶۳ ind.m۲ and ۰.۰۳۲±۰.۰۰۵ g.m۲ in summer. So, there was a significant difference between the density and biomass in different seasons (p<۰.۰۵), which is due to their reproductive cycle. According to these results, it was concluded that the macrobenthic in obtaining and different places have a large limit on the density, if you use these communities to influence the environment, you have to consider them natural.