Alpine ecosystems are particularly vulnerable to climate change due to their pronounced seasonal temperature fluctuations. Future projected atmospheric temperature increases may alter the phenology of insects in the Australian alps, imposing nutrient limitations on alpine food webs.
Aquatic insects are one of the main biological components in Australian alpine ecosystems and have a prominent role in cross-ecosystem nutrient fluxes between aquatic and terrestrial environments. Aquatic insects are particularly high in poly-unsaturated fatty acids (PUFA) that are essential but limited in terrestrial ecosystems. Cross-ecosystem fluxes, driven by emerging aquatic insects, transport these scarce nutrients to land, where they are consumed by terrestrial animals. As an initial step toward understanding nutrient dynamics in these systems, we conducted a study to quantify temporal and spatial variation in the abundance and diversity of alpine insects and the transfer of aquatic insect fatty acids into the terrestrial environment.
Insects were sampled monthly at Falls Creek, Victoria, Australia from November 2024 until May 2025 using emergence and malaise traps. Temperature loggers were deployed over the same time frame to collect water and air temperature data. The abundance and biomass of insect orders were determined, and fatty acids were quantified to explore seasonal variation in aquatic and terrestrial insects.
Insect emergence rates and biomass varied significantly across seasons peaking in summer and declining into autumn. Preliminary findings revealed significant differences in PUFA levels between aquatic and terrestrial insects. These results suggest seasonal variation in the cross-ecosystem transfer of insect-derived fatty acids in alpine ecosystems. Further analyses for the study are currently in progress. Future focus will explore seasonal variation through development of models that link antecedent temperatures with biomass and fatty acid loads. Moreover, these models will be used to infer how nutrient landscapes may shift with changing climate under future climate scenarios.