Trichoptera diversity in Icelandic springs

Abstract
The aim of this study was to characterize the Trichoptera fauna of freshwater springs in Iceland and to relate distribution of caddis larvae to environmental properties of the springs. Out of a total of 48 springs sampled, Trichoptera larvae were found in only eleven. Larval densities were low, as was species diversity. Only three of the 12 species known to occur in Iceland were found: Apatania zonella, Limnephilus griseus, and Limnephilus affinis. The occurrence of A. zonella in springs in North-Iceland may suggest that springs might play a role as refugia for this species that is otherwise excluded from the area by larvae of the predatory caddis species Potamophylax cingulatus, which seems to be absent from spring habitats. Caddis larval abundance was higher in rheocrene springs and in springs with sandy substrate, and decreased with increasing water temperature. Presence or absence of Trichoptera larvae, on the other hand, was not associated with any of the environmental variables measured.