Cumulative impacts of multiple stressors on freshwater biodiversity and ecosystem function likely increase with elevation, thereby possibly placing alpine communities at greatest risk. Here, consideration of species traits enables stressor effects on taxonomic composition to be translated into potential functional impacts. We analyzed data for 47 taxa across 137 mountain lakes and ponds spanning large latitudinal (491 km) and elevational (1,399 m) gradients in western Canada, to assess regional and local factors of the taxonomic composition and functional structure of zooplankton communities. Multivariate community analyses revealed that small body size, clonal reproduction via parthenogenesis, and lack of pigmentation were species traits associated with both introduced non‐native sportfish and also environmental conditions reflecting a warmer and drier climate—namely higher water temperatures, shallower water depths, and more chemically concentrated water. Thus, historical introductions of sportfish appear to have potentially induced greater tolerance in zooplankton communities of future climatic warming, especially in previously fishless alpine lakes. Although alpine lake communities occupied a relatively small functional space (i.e., low functional diversity), they were contained within the broader regional functional structure. Therefore, our findings point to the importance of dispersal by lower montane species to the future functional stability of alpine communities.

The cumulative impacts of multiple environmental and anthropogenic stressors on freshwater biodiversity have been studied in systems across the globe. The magnitude of multiple interdependent stressors on alpine systems may lead to increased primary productivity and jeopardize these unique communities. In this review, the consequences of individual stressors on alpine lake and pond ecology are synthesized, as well as the cumulative and potentially synergistic or antagonistic effects of multiple stressors. Beside temperature variability, other stressors reviewed include ultra violet (UV) radiation, organic pollutants, nutrient deposition, and biological invasions. Each stressor was evaluated individually and in combination with increasing water temperatures. In alpine environments, climatic warming is anticipated to increase with elevation, therefore amplifying the effects of temperature-related responses. The purpose of this review is to highlight the ecological effects of climate change on alpine lakes and ponds in the Rocky Mountains of North America and fill knowledge gaps between disciplines of aquatic studies. This work underscores that to better understand and face the overall effects of climate change on alpine biota, investigations must continue to assess the compounded impacts of multiple stressors. Emphasis must be put on the standardization of monitoring methods across alpine regions to aid in consistent trend and prediction analysis within the context of both current and future climate change.

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