Distribution pattern and biomass estimation of benthic invertebrates in Aras reservoir

This study was carried out at monthly basis covering six sampling stations in Aras reservoir in 1995, The samples were collected by Ekman grab with 3 replicates, The results Showed that Oligochaetes were the dominant taxa in this reservoir which were observed all year round and had the highest abundance and biomass, The Chironomidae were the second dominant family. Gammaridae and Mysidae had the least abundance and biomass, Maximum biomass of Oligochaetes was observed in spring with the average figure of 19.03 g/m2 and minimum biomass was observed in winter with average biomass of 5.87 g/m2 Maximum and minimum biomass or Chironomidae were recorded in summer and spring, of which their correspond average biomass were 1.52 and 0.06 g/m2, respectively. The highest and lowest biomass of Mysidae family were observed in summer and spring with the average biomass of 0.46 and 0.00 g/m2, respectively. Gammaridae family observed only in summer. The differences of biomass of these 3 families were significant based on kruskal-wallis nonparametric test (p