Evaluation seasonal distribution patterns and biodiversity of macroinvertebrates communities in Aji-Su River (Golestan province)

Benthic communities are considered as bio-indicators in aquatic ecosystems. The purpose of the present study was to the biological evaluated of the Aji Sou River based macrobenthic population structure. Macrobenthic invertebrate samples were collected seasonally from 4 stations (each with 3 replications) for one year using a Surber sampler with a coating surface 30 × 30 cm. Totally, 1106 samples of benthic organism were identified, which highest frequency was observed for Diptera and Ephemeroptera in the autumn, while other frequent bastards had a low prevalence rate. The largest distribution of the benthos was obtained at stations 2 and 3. Multi-dimensional Scaling (MDS) and clustering chart show that, due to the frequency of Diptera,Oligocheta and Ephemeroptera orders at stations 2, 3 and 4 of the autumn and summer, the groups are separated in 3 separate sections. Diversity index (Shannon-Weaver), dominancy index (Simpson) and species richness (Margalof) was statistical analyzed. Results of this study indicate that the most diversity index (1.36±0.16), dominancy index (0.77±0.03) and species richness (1.37±0.21) were in fall season, while the lowest amount was obtained in the warm season (summer). There were significant correlations between the different index of biological and some water parameters, including temperature, Do, salinity, EC and TDS. Overall, the results were determined that aquatic insects constitute the dominant population of the benthic fauna in Aji-Su River. The Macrobenthos had the greatest density and diversity in the autumn.