Insights into spatio-temporal dynamics of invertebrate communities from two alpine pasture ponds

This study aimed to characterise the composition, structure and trophic organisation of the macroinvertebrate communities of two pasture ponds – one natural and one artificial – in the Italian Prealps. Faunal composition was studied during the snow-free period in 2003–2004 and compared with data collected in 1984–1985. Insects (i.e., Coleoptera, Diptera and Heteroptera) prevailed (58%), followed by Tubificidae (40%). Overall, higher taxonomic diversity was assessed in the natural pond, which was less disturbed by livestock and humans. The invertebrate assemblages also had different inter- and intra-pond functional characteristics based on the substrate type (e.g., silt-mud sediments were dominated by collector-gatherers, burrowers and drought-tolerant taxa), vegetation cover and hydrological regime. The faunal composition of the two ponds was different from that reported 20 years prior due to the meteorological conditions (e.g., 2003 was exceptionally hot and dry), human activities (e.g., biomanipulation practices) and natural factors (e.g., siltation); these results emphasise the high vulnerability and resilience of alpine ponds.