Ecological quality status of stressed coastal benthic ecosystems in Nayband Bay from the northern Persian Gulf, Iran using AMBI, M-AMBI, Bentix, and H´ indices

Nayband Bay has been greatly influenced by a variety of human disturbances over the last three decades. The present study was undertaken to assess the ecological quality status of macrobenthic communities in Nayband Bay sediments using four benthic indices namely AMBI, M-AMBI, BENTIX, and H´. The sediment samples were taken for macrobenthos extractions and determination of grain size analysis, Total Organic Matter (TOM), and Total Organic Carbon (TOC) using a Van Veen grab. A total of 47 macrobenthos taxa (genus and species) were identified among 34825 individuals in the sampling area. Polychaeta, Malacostraca, Bivalve, Gastropoda and Echiura were the most abundance taxon with 23 (48.9%), 11 (23.4%), 6 (12.7%), 5 (10.6%), and 2 (4.2%) species. The results showed that the macrobenthic communities were characterized by sensitive (EGI) or indifferent (EGII) species of AMBI ecological groups. The opportunistic species (EGIV and V) namely Capitella capitata, Cirratulus ciratus, and Scolelepis sp. were dominated at stations with high TOC. These stations were close to the beach, where the organic matter discharges and wastewaters have been released from industrial outfalls. In general, the EcoQs were “good” or “acceptable”, although four indices showed some differences in the EcoQs classifications for a given site. The results of the present study indicate that the complementary use of different indices, especially sensitivity/tolerance-based indices, is recommended for the ecological-status assessment of the Iranian coastal waters of the Persian Gulf.