Determination of Habitat Suitability Index and the most significant factors on distribution pattern of Capoeta capoeta in Roodbabol River, Mazandaran Province.

Presence-absence and abundance of each fish species in a river habitat depends on several factors and they prefer a specific range of each habitat factor. The present study was carried out to investigate habitat suitability index of Capoeta capoeta and the effect of habitat factors on its distribution and abundance in Roodbabol branch of the River Babolrood (Mazandaran Province). To do, fish sampling was performed at 20 sampling stations during December 2017 and January 2018 and 11 habitat factors were measured at each sampling station. Then, habitat suitability curves for each parameter and suitability index of each station were obtained using HABSEL software. Also, determination of distribution pattern of C. capoeta and its relation with the best habitat factors were surveyed using dbRDA analysis according to its abundance at each station in Primer+Permanova (Ver. 6).Based on the HABSEL results, C. capoeta inhabiting in Roodbabol prefers wide locations with low water flow speed, temperature between 14 to 18°C, average depth (22 to 30 cm), average altitude (140-180 m), average EC (260-300 μS/cm), small grain size of substrate rocks (100-125 mm), high level of dissolved oxygen (12 to 13 mg/l), and average salinity (1.5-1.7 mg/l) which are covered by bush and shrubs and shadow level is 41-70%. Also, dbRDA graph based on DistLm model indicated that factors of depth and width in the first order and water flow with EC in the second order affected the abundances differences of C. capoeta among various stations.