Abstract

The purpose of this study is to evaluate the seasonal diversity of benthic macroinvertebrates in the Bahrekan bay (situated in the northwest of the Persian Gulf) using diversity and evenness indices. Physiochemical parameters of water, grain size analysis and percentage total organic matter (TOM) of sediment were assessed during four seasons. Hence, the samples of benthic macroinvertebrate and sediment were obtained from fifteen sites along the Bahrekan Bay, from November 2008 to August 2009. The diversity of benthic macroinvertebrates in fifteen sites was calculated. Also, the differences between physico-chemical parameters of sea water, percentage TOM and grain size of sediment and diversity indices were determined (P = 0.05). The diversity of all stations was compared with each other in each season. The correlation coefficients of all above parameters were determined. The highest diversity was obtained in winter (Simpsson index: 0.13 ± 0.01, H´: 3.47 ± 0.06) and the lowest diversity was obtained in autumn (Simpson index: 0.16 ± 0.01, H´:3.17 ± 0.06). The annual mean of Simpson diversity index was 0.15 ± 0.04 which indicated that macrobenthose in Bahrekan bay have a good variation. The results of Shanon–Wiener, Brilluin and N1 (number of equally common species) indices confirmed the results of Simpson index. In stations where diversity had little fluctuations based on N1 index, the degree of the fluctuations were more recognizable. At stations near the shoreline, the diversity indices was categorized as moderate pollution (H´: 1 - 3) due to the fishing activities.

Key words: Benthic macroinvertebrate, biological indicators, species diversity, ecological status, Persian Gulf.