| Institution: | (1) Biotechnical Faculty, Department of Biology, University of Ljubljana, Ve na pot 111, SI-1000 Ljubljana, Slovenia;(2) Fisheries Research Institute of Slovenia,  upanieva 9, SI-1000 Ljubljana, Slovenia |
| Abstract: | The relationship between caddisfly assemblage structure and four selected environmental variables (substrate, water depth, flow type and amount of the coarse particulate organic matter) was investigated in a Slovenian lowland stream. Caddisflies were sampled at four stream reaches according to selected microhabitat types. All together, 168 quantitative samples were taken at 21 sampling points between October 1998 and July 1999. Of 48 collected species, 30 were included in the analysis. Significant correlation was observed between species and environmental variables. As a complement to a CCA biplot representation, species assemblages within the community were also determined using cluster analysis. Nine groups and subgroups were established. Most caddisfly species prefer coarse substrate in shallow water (5–10 cm) with chute water flow, whereas few species were found on fine substrate in deep water. A significant positive correlation was found between mean substrate size and total number of species, and between indices of species richness and diversity, whereas depth did not show any correlation with these parameters. Seven species were found mostly in marginal habitats, whereas four (Potamophylax rotundipennis, Anabolia furcata, Athripsodes bilineatus and Lithax obscurus) did not show any strong preferences for selected parameters. In addition, habitat preferences were associated with the feeding types of the caddis larvae. |
