Application of biotic indices in assessing the ecological quality status of Bahrekan estuary (Persian Gulf).

The aim of present study was to examine the macro invertebrates as an assessment tool for characterization of the state of Bahrekan estuary in Persian Gulf, by using different biotic indices. An investigation on benthos was carried out during autumn 2008 to summer 2009 in the Bahrekan estuary (Persian Gulf). In order to identify and assess the benthic community structure, seasonal sampling was done from 21 stations with three replicates using van veen grab (./285 m2). The ecological indices, such as (AMBI, BI and Bentix), Shannon-Wiener index (H'), species richness (S) were applied to the available benthic species data, and evaluated comparatively. The grain size of sediments and total organic matter as essential factors in distribution and population diversity of macrobenthos communities were also analysed. According to the results, 17 groups of macrobenthos were identified. Out of 111 genus/species identified in this study, Gastropoda was the dominate group (79.8%), followed by Bivalvia (5.5%). Pyrgohydrobia sp. belonged to gastropoda was dominant in all of seasons. The results showed that all of the stations are characterized as muddy bottom and Bahrekan estuary are classified in slightly to moderate pollution status.