Patterns of fish communities along a mountain river : the Upper Coruh river (Turkey)

Distribution of fish communities along the submountain river (upper Coruh River, Northeastern of Turkey) was assessed to evaluate course of the longitudinal pattern in fish species diversity. The watershed area of Coruh Basin is 21.000 km[^2], river length 376 km and it flows into Black Sea in northeastern Turkey at average discharge of 149 m[^3] s[^-1] (range: 45.2.1215 m[^3] s[^-1]). Fixed-site electrofishing sampling at five sites located 15.210 km from river source at 2100-950 m a.s.l (Q values ranged 5.200 m[^3] s[^-1]) was conducted from March 2001 to March 2002. A total of 12 species were collected. Number of species (8-10) did not differ among sites suggesting no longitudinal changes, but Shannon-Wiener biodiversity index (H') increased downstream from 1.23 to 1.82. Two distinct fish assemblages were identified. Most abundant species were Leuciscus cephalus and Alburnoides bipunctatus. Both Oncorhynchus mykiss and Cyprinus carpio collected rarely are exotic fishes for Coruh River.