Spatial and temporal variation in fish assemblage structure of Cekerek stream

In this study spaital and temporal variations in fish assemblage structure of Çekerek Stream in relation to environmental parameters were investigated at 8 stations seasonally sampled between 2017 and 2018. A total of 1255 fish individuals belonging to 13 fish species of 2 families were obtained with electroshoker. Of the fish sampled, Squalius seyhanensis was the dominated fish species with 30.28 % by number. This species was followed by Capotea banarescui (23.51%), Capotea sieboldii (13.63%), Alburnus geokani (8.05%), Chondrostoma angorense (7.33%), Oxynoemacheilus sp. (5.18%) ve Barbus anatolicus (4.54%), Pseudorasbora parva (3.11%), Oxynoemacheilus kosswigi (2.87%), Rhodeus amarus (1.20%), Alburnoides kurui (0.16%), Carassius auratus (0.08%) and Vimba vimba (0.08 %). Çekerek Steram's catch per unit effort (CPUE), Species Diversity Index (H') and evenness (J) were 258.65 (indiviuals/30 min), 1.95 and 0.76, respectively. Canonical Correspondence Analysis showed that environmental parameters explained 52.8 % of fish assemblage structure. Conductivity, salinity and pH were the most, dissolved oxygen was the second important parameter affecting the fish assemblage. Theoritically number of fish species in streams increases from the upstream to the downstream. This trend of increase in Çekerek Stream was observed until station 4 which is located to the entrance of Çekerek Dam Lake. Number of fish species decrased in river sction below the Dam Lake. This situation showed the negative effects of dams on stream ecology were true for Çekerek Stream. Keywords: Yeşilırmak River Basin, Fish Assamblage, Spaital and Temporal Variation, Environmental Parameters, Çekerek Stream, CCA.