Microhabitat preferences of spined loach, Cobitis sp. in the Grabia River--multivariation approach

The pattern of microhabitat preferences of spined loach was examined in a natural, unpolluted lowland river. This fish co-occurred with 9 other species but non-random association was noted only with Ukrainian Lamprey, the most abundant species in the studied fish community. Spined loach was distributed only in areas adjacent to river banks. Microhabitat variables configuration available for the examined fish was represented by three axes obtained by principal component analysis. The presence/absence distribution pattern of spined loach was negatively dependent on the abundance of gravel and pebbles (component 1) and positively related to low velocity (component 3). The abundance of coarse sand (component 2) had no effect on the spined loach distribution pattern and fish randomly used this type of microhabitat. Although that substratum particle size plays an important role in spined loach distribution, in the natural environment this fish realised its microhabitat preferences by the avoidance of unfavourable configuration ofmicrohabitat variables such as high velocity and coarse-grained substrata (gravel and pebbles).