How organic pollution and habitat alteration influence the trophic habits of Perlodes intricatus (Pictet, 1841) in alpine rivers?

In this study, we analysed the diet of two populations of Perlodes intricatus (Pictet, 1841) inhabiting river sections characterised by different environmental quality. Macrobenthic communities and nymphal gut content data were acquired in a nearby pristine environment and in a station compromised by sewage discharges. No differences in size were detected between these populations. Both populations select positively Chironomidae as prey, but marked differences are evident between their diet. Nymphs from pristine station feed on a wide range of prey, but also include algae and organic detritus. By contrast, nymphs from polluted station show a different and restricted trophic spectrum, likely because of the reduced prey availability. Interestingly, the occurrence of fine organic detritus in these latter nymphs is much higher, evidencing a shift to a more collector-gatherer feeding. This study shows that some Perlodidae can survive and develop in contaminated environments, also due to their trophic plasticity.