Assessment of aquatic ecosystem health in Gorgan Bay based on biotic indices

The relationship between spatial patterns of macrobenthic community characteristics and environmental conditions (dissolved oxygen, temperature, salinity, organic matter content and sediment particle size) was studied at ۱۲ stations in Gorgan Bay (South Caspian Sea, Iran), seasonally in ۲۰۱۷. A total of ۸۸۰۳ individuals belonging to ۱۱ families and ۱۱ species were identified. Three species of polychaeta including Streblospio gynobranchiata, Tubificidae and Hediste diversicolor were the most dominant group in terms of abundance, making up ۷۹.۳% of all specimens. The highest density (۴۷۳۳ ind m-۲) was observed at St. ۱ while the lowest (۱۱۶۶ ind m-۲) at St. ۹. Biotic indices (i.e. AMBI, BOPA and BENTIX) were used to determine the quality of the bay. Gorgan bay is divided into two distinct zones (eastern and western regions) based on MDS analysis and ecological status. Generally, eastern part of the bay revealed the lowest abundance and biodiversity of macrobenthos. Our results suggest the effect of sediment particle size and TOM as significant parameters on distribution of macrobenthic community in Gorgan bay, South Caspian Sea.

کلیدواژه ها:

Gorgan Bay ، Environmental parameters ، Biotic indices ، Spatial distribution