Ecological investigation of zooplankton abundance in the river Haraz, northeast Iran: Impact of environmental variables

摘要: The influence of physicochemical properties Haraz river on its zooplankton composition and abundance were investigated at three sites for one year between August 2009 July 2010. present study records the first time aspects zooplankton diversity in relation to the environment river. Only groups of found: Rotifera with eighteen genera; Cladocera nine Copepoda six genera. was predominant group (64.89%), followed by (19.62%) (15.32%). Upstream, abundance 805 individuals/m3, while it varied from 922 1126 ind/m3 downstream. Alkaline pH nutrients main environmental factors which affected Site variation dominance, diversity, evenness richness calculated. revealed that presence certain species, such as Lepadella sp., Mesocyclops Polyarthra sp. Brachionus sp. is considered be a biological indicator for eutrophication. calculated Jack1 values 1 3 7.624, 16.426 19.221, respectively. Shannon-Wiever species index (H’) also different all viz., site (1.992), 2 (1.21) (2.48). Simpson’s dominance index (H) value was highest (0.692), indicating maximum whereas 3 lowest (0.227) highest. Overall, our results showed changes water quality have considerable effects assemblages can potentially affect functioning these ecosystems.