Spatial and temporal variations of macrobenthic communities of the southern coast of the Caspian Sea, Pareh sar

In the present study, macrobenthos were sampled using a grab in Pareh Sar coast at 7 station and two depths (5 and 10 m) during 4 seasons in 2016. In total, 10472 individuals belonging to 22 Species from 13 families were counted. The highest abundance of macrobenthos (648±170.79) was seen in spring while the most biomass (36.21±2.5 gr/m2) was observed in winter. The most abundance group was bivalves (40%) followed by crustaceans (36%), annelids (22%) and gastropods (2%). PERMANOVA analysis showed that season and depth affected the abundance, biomass, species richness, species composition and community structure significantly. The results also showed that with increasing the depth from 5 to 10 m, macrobenthos abundance enhanced in spring, summer, autumn and winter by a magnitude of 4, 2, 1 and 9, respectively. Furthermore, Shannon index, spices richness and biomass increased from 5 to 10 m depth. According to our results, it can be concluded that abundance, biomass and diversity index of macrobnthic communities vary greatly with season and depth. Therefore, natural fluctuations of these variables should come into account while using macrobenthos for environmental impact assessment.