Investigation on the effects of some environmental factors on abundance and biodiversity of macrobenthos community in Karaj River

Macrobenthos community like other animals are affected by their peripheral environment and their diversity is dependent on their sensitivity to the environmental factors. The aim of this study was to investigate the impacts of some environmental factors on abundance and biodiversity of macrobenthos community in Karaj River. Samples were taken from 10 stations in two seasons and 11 environmental factors were measured. A total number of 8032 macrobenthos belonging to 10 orders and 38 families were identified. Baetidae and Chironimidae were the most abundant in autumn and spring, respectively and changes in altitude (2 seasons) and temperature (autumn) and depth (spring) were the most driving factors in determining pattern of abundance and combination of species. Biodiversity pattern and seasonal changes in the variety of benthic invertebrates in the Karaj River were also determined by the abovementioned environmental factors. Altitude, temperature and depth had effects on the habitat which was further responsible for changes in biodiversity, abundance, species’ structure and combination.