Interactions between temperature and predation impact insect emergence in alpine lakes

Abstract

While insect populations are simultaneously threatened by many local‐ and global‐scale stressors, the interacting effects of these factors remain poorly understood. These interactions between stressors, whether additive or antagonistic, may have profound effects on our assumptions about and predictions for any given system. Here we address this gap by exploring the interactive effects of introduced predators and elevated temperatures on emerging aquatic insects across alpine lakes. Using a crossed factorial field survey, we examine whether warmer temperatures either directly affect the magnitude or diversity of insect emergence, or mediate the impacts of predation via interactions with predator presence. Based on data from more than 11,000 insects collected across a two‐year period, we find a 71% reduction in insect emergence associated with an additional 3.6°C of water temperature in oligotrophic alpine lakes. While our work confirms prior findings that predator presence drives strong reductions in insect emergence, we find that the effects of predation are significantly weaker in warmer lakes (2% reduction in warmest lakes studied vs. 75% reduction in coldest). Combining our results with regional studies of predator communities to identify mechanisms suggests that the interaction effects between temperature and predator presence are likely due to changes in predator behavior across temperatures. Critically, to fully understand the multiple stressors that impact insect populations and predict their future effects, we must consider the interactions between stressors across spatial scales.

Climate change and the biodiversity of alpine ponds: Challenges and perspectives

“…Water temperature determines alpine ponds' community composition (Miller et al., 2021 ). Warmer waters have interactive effects with predation patterns on species growth, distribution, and intra‐guild competition (Loewen et al., 2020 ; Owens et al., 2023 ; Shepard et al., 2022 ; Symons & Shurin, 2016 ). For example, as waters warm and species migrate to higher elevations, preferential consumption of large body zooplankton by predators ( Oncorhyncus mykiss ) allows smaller body zooplankton to dominate colonization patterns (Jones et al., 2020 ).…”

Climate change and the biodiversity of alpine ponds: challenges and perspectives

“…Water temperature determines alpine ponds' community composition (Miller et al, 2021). Warmer waters have interactive effects with predation patterns on species growth, distribution, and intraguild competition (Loewen et al, 2020;Owens et al, 2023;Shepard et al, 2022;Symons & Shurin, 2016). For example, as waters warm and species migrate to higher elevations, preferential consumption of large body zooplankton by predators (Oncorhyncus mykiss) allows smaller body zooplankton to dominate colonization patterns (Jones et al, 2020).…”