Feeding habits of Perlodidae (Plecoptera) in the hyporheic habitats of Alpine streams (Trentino-NE Italy)

Toltal of 75 nymphs of Dictyogenus fontium, Perlodes intricatus and Isoperla (cf) rivulorum and 22 juvenile Perlodinae were collected in hyporheic habitats of the Noce Bianco watershed (Trentino, NE Italy). The identification of their life stages allowed considerations regarding their presence in the hyporheos, mainly used as a refuge habitat, particularly during vulnerable phases of their life cycle (neanid stage and pre-imaginal phase). This function is possible, given the more stable environmental conditions and the minor predatory pressures in this habitat. The gut content analyses of the three species assigned them to the engulfers-carnivorous functional feeding group, with slight resource partitions between the two largest species. P. intricatus appears to feed on less mobile and fleshy preys while D. fontium prefers more sclerotized and active preys. The results indicate that the hyporheos acts not only as a refuge area but also as a trophic habitat for some Perlodidae species.