Study of Biodiversity of Macrobenthos in Shadegan Wetland in Spring and Summer 2015 with Emphasis on Dominant Species

The aim of present study was examining the effects of changing seasons (spring and summer) on macrobenthos of Shadegan Wetland. The study was conducted in 2015 in seven stations along the wetland. To investigate the role of environmental factors on macrobenthic community changes, pH, temperature, EC, amount of dissolved oxygen and salinity were measured by portable HQ40d. Sediment sampling for identifying macrobenthos, the percentage of organic matter and sediment grain size analysis were done by Van Veen Grab Sampler with cross section of 0.025m2. The result of measuring physical and chemical factors showed a meaningful non-difference between the spring and summer seasons, but showed a difference in the number per square meter and the identified macrobenthos between the two seasons. The abundance was higher in spring. In spring, 48520 ind. 21 m2 from 6 macrobenthos classes were counted that the highest abundance were Gastropod (91.34 %), Oligochaeta (3.79 %), Polychaete (2.39 %), insects (1.73 %), Bivalves (0.65 %), and crustaceans (0.082 %). In summer, 48520 ind. 21 m2 from 6 macrobenthos classes were counted that the highest abundance were Gastropod (95.28 %), Bivalves (2.53 %), crustaceans (1.86 %), Oligochaeta (0.103 %), Polychaete (0.103 %), insects (0.103 %). In the study, the change of seasons has no significant effect on studied parameters such as temperature. In conclusion, the factors, except seasonal factors, affect the benthos abundance in spring and summer.