Habitat use of two nemacheilid fish species, Oxynoemacheilus bergianus and Paracobitis sp. in the Kordan River, Iran

Abstract

Understanding habitat ecology of fish is a basic step for developing management and conservation measures. In this study, the habitat use and selection of two little-known nemacheilid species, Oxynoemacheilus bergianus and Paracobitis sp., in the Kordan River, Iran were analyzed. The river was sampled at 66 equally spaced sites. A number of environmental variables and the relative abundance of each species were recorded at each site. O. bergianus mostly selected lower parts of the river, with lower depth and width, higher velocity, finer substrate, sparse riparian vegetation, less shade, and boulder cover. Paracobitis sp. mostly selected higher parts of the river, with higher slope, lower width, lower velocity, relatively higher depth, course substrate, bushy riparian vegetation, moderate shade, and different types of cover. In some cases the distribution patterns of both species were different from mentioned maximum habitat selection patterns. The intraspecies distribution patterns were similar for different size groups of each species, while the patterns were significantly different at interspecies level. The habitat characteristics may explain the strategies adopted by the two species to reduce interspecific competition for space and maximize net energy gain, or adaptation to the specific parts of the river.