A Functional Approach to Zooplankton Communities in Mountain Lakes Stocked With Non‐Native Sportfish Under a Changing Climate

Abstract

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.

Quantifying seasonal succession of phytoplankton trait‐environment associations in human‐altered landscapes

“…While correlated variables emphasized trait syndromes underlying the seasonality of functional groups with preferences for distinctive lake types (e.g., Reynolds et al 2002), our analysis was also limited by availability of trait information. For instance, except for greatest axial linear dimensions, all traits were categorical (binary) and thus apt to cluster in ordination space (Petchey and Gaston 2006; Redmond et al 2018). Continuous measures, such as demographic or stoichiometric rates, can further distinguish related species and offer other, potentially more mechanistic, functional insights (e.g., Edwards et al 2013; Meunier et al 2017).…”

“…Trait-based functional approaches provide mechanistic understanding of community structure (e.g., niche characteristics; McGill et al 2006) and means of translating effects of environmental change on species diversity into potential consequences for ecosystem functioning (e.g., Lavorel and Garnier 2002;Petchey and Gaston 2006;Redmond et al 2018). Recognition of species traits as fundamental to niche differentiation and broader ecosystem properties has increased in recent decades (e.g., Díaz and Cabido 2001;Hooper et al 2005; Weiss and Ray 2019) along with advancements in functional classification of phytoplankton (reviewed by Salmaso et al 2015;Weithoff and Beisner 2019).…”

Factors of surface thermal variation in high-mountain lakes of the Pyrenees

“…Temperatures increase can drive changes in water bodies’ communities, such as functional traits, composition, biomass or abundance. For instance, in Canadian lakes, it was found that water temperatures were negatively related to zooplankton body size, a similar effect to the one produced by fish predation, and these combined effects would be non-additive [ 58 ]. Therefore, lakes warming would favour smaller zooplankton species.…”

Macroecological drivers of zooplankton communities across the mountains of western North America

“…For instance, alpine ecosystems are frequently compared to those in the arctic on the basis of their biological and environmental similarities (Billings 1973), and both are projected to experience increasingly rapid climate change (Bradley et al 2004, Pepin et al 2015. However, barring the existence of impermeable dispersal barriers, the alpine environment may provide critical climate change refugia for organisms forced from lower elevation habitats by increasing temperatures (Redmond et al 2018). However, barring the existence of impermeable dispersal barriers, the alpine environment may provide critical climate change refugia for organisms forced from lower elevation habitats by increasing temperatures (Redmond et al 2018).…”

“…The distinctive topographic complexities of mountain regions may also impede biological connectivity, with the potential implication of reducing propagule pressure and the ability for species to reach and colonize novel habitats (Dong et al 2016). However, barring the existence of impermeable dispersal barriers, the alpine environment may provide critical climate change refugia for organisms forced from lower elevation habitats by increasing temperatures (Redmond et al 2018). Further, mountains are the source of headwaters and often exist in remote or protected areas, providing unique opportunities for detecting subtle effects of regional drivers not blurred by the confounding impacts of more pronounced local perturbations (e.g.…”