Habitat suitability index of Sefidrud hillstream loach (Oxynoemacheilus bergianus) in Taleghan River (Sefidrud River basin: Alborze province)

Study of habitat suitability indices play an important role to provide detailed description of habitat features of a species. Therefore, this study was conducted to investigate the habitat features and habitat suitability index (HSI) of Sefidrud hillstream loach (Oxynoemacheilus bergianus) in its distribution range within the Taleghan River. To study the habitat characteristics of this species in Taleghan River, its abundance and 12 habitat variables, including elevation (m), depth (cm), river width (m), slope (degree), flow velocity (m/s), water temperature (°C), EC (us), TDS (ppm), average diameter of substrate stones (cm), number of big stone (>25cm) and substrate index (%SI) at 33 stations from the downstream to upstream were measured. The result shows that suitable habitat of O. bergianus are areas with height ranges 1750-1800 m, depth in range of 10-40 cm, width in range of 12-24 m, flow velocity ranges 0.9-1.2 m/s, slope in range of 0.5-1 degree, pH in range of 7.5-8, water temperature in range of 13-15.5°C, EC in range of 630-740 µs, TDS in range of 200-250 ppm, number of big stone lesser than 5 piece per quadrate, average diameter of substrate stones less than 15 cm and substrate index percentage in range 4-6%. Presence of environmental features with a habitat suitability index of 0.524 indicated that Taleghan River is average habitat for O. bergianus in terms of habitat suitability index.