Potential ecotoxicological effects of global change on organisms inhabiting high-mountain lakes in the Alps

Abstract

High-mountain lakes in the Alps are highly sensitive freshwater ecosystems, increasingly impacted by climate change, pollution, and anthropogenic disturbances. This discussion assesses the ecotoxicological effects of global change such as rising temperatures, earlier snowmelt, glacier retreat, permafrost thaw, increased ultraviolet radiation, and pollutant deposition on aquatic organisms. A systematic literature search identified only nine studies explicitly addressing these ecotoxicological aspects. Given the limited availability of studies on Alpine high-mountain lakes, this analysis draws mainly on research from other high-altitude aquatic ecosystems. Rising temperatures alter metabolic rates, species distributions, pathogen susceptibility, and trophic interactions, disrupting ecological balance. Glacier retreat and permafrost thaw modify nutrient cycling, favoring cyanobacteria over diatoms, with cascading effects on food webs. These temperature shifts also increase oxygen demand and metabolic stress in aquatic organisms. Biofilm and zooplankton community shifts further destabilize food web dynamics, while macroinvertebrate assemblages become dominated by thermophilic taxa, affecting organic matter decomposition and nutrient availability. Amphibians are particularly vulnerable, as warming facilitates disease outbreaks like chytridiomycosis. Additionally, glacial melt and permafrost thaw release toxic substances, which bioaccumulate across trophic levels, inducing oxidative stress and reproductive impairments in fish, amphibians, and invertebrates. Contaminant biomagnification threatens entire food webs, compromising ecosystem as well as human health. Increased ultraviolet radiation exacerbates oxidative stress and interacts with pollutants, intensifying physiological damage. Future research should prioritize long-term monitoring, controlled exposure experiments, and predictive models. Conservation strategies must mitigate contaminants and enhance ecosystem resilience to protect biodiversity in these fragile environments.

Keywords: Amphibian; Aquatic organisms; Chemical pollution, climate change; UV radiation.