Climate constrains lake community and ecosystem responses to introduced predators

Abstract

Human activities have resulted in rising temperatures and the introduction or extirpation of top predators worldwide. Both processes generate cascading impacts throughout food webs and can jeopardize important ecosystem services. We examined the impact of fish stocking on communities and ecosystems in California mountain lakes across an elevation (temperature and dissolved organic carbon) gradient to determine how trophic cascades and ecosystem function vary with climate. Here, we show that the impact of fish on the pelagic consumer-to-producer biomass ratio strengthened at low elevation, while invertebrate community composition and benthic ecosystem rates (periphyton production and litter decomposition) were most influenced by predators at high elevation. A warming climate may therefore alter the stability of lake ecosystems by shifting the strength of top-down control by introduced predators over food web structure and function.

Taxonomic, functional and phylogenetic metacommunity ecology of cladoceran zooplankton along urbanization gradients

“…Large zooplankton species are known to be more vulnerable to high temperatures and pollutants (Moore andFolt 1993, Symons andShurin 2016). Competition among zooplankton species is often size mediated, as numerous studies have demonstrated that large zooplankton species are stronger competitors and tend to competitively exclude smaller species from local communities (Brooks and Dodson 1965, Dodson 1974, Shurin 2001, Symons and Shurin 2016. The higher temperatures in more urbanized ponds and perhaps also other unmeasured anthropogenic pressures, such as pollution, could have acted as a filter and selected against larger species in our study system, thus resulting in significant pure effects of urbanization on body size and phylogenetic turnover ( Fig.…”

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

“…Across our study region, lake catchments received the most precipitation during winter months (November-February; data not shown), when precipitation falls as snow. The relatively large proportions of community variation attributable to temperature, solar radiation, and precipitation underscore the vulnerability of mountain zooplankton communities to climate change, which may be compounded by climate-mediated changes to other more local environmental variables, such as land cover alteration or enhanced predation rates by exotic fishes (Messner et al 2013, Symons andShurin 2016). For instance, low winter snow accumulation may lead to reduced water levels or desiccation in smaller temporary ponds, while high rates of runoff from large snowpack may disrupt biota in mountain lakes (Girdner and Larson 1995).…”

Rapid evolution of thermal plasticity in mountain lakeDaphniapopulations

“…Changes in temperature might directly affect zooplankton physiology or indirectly influence zooplankton through bottom–up effects. Often the effects of temperature cannot be disentangled from the effects of nutrients, as low elevation, warm, lakes in Sierra Nevada (CA) also have greater primary productivity as well as higher levels of detritus and dissolved organic carbon (Symons and Shurin ). Hence, the effect of lake temperature on size at maturity could be confounded or be a synergistic response to high temperature and food availability, which can potentially increase growth and/or egg production of zooplankton (Kvile et al ).…”

“…Often the effects of temperature cannot be disentangled from the effects of nutrients, as low elevation, warm, lakes in Sierra Nevada (CA) also have greater primary productivity as well as higher levels of detritus and dissolved organic carbon (Symons and Shurin ). Hence, the effect of lake temperature on size at maturity could be confounded or be a synergistic response to high temperature and food availability, which can potentially increase growth and/or egg production of zooplankton (Kvile et al ). In our common‐garden experiment, food availability was controlled, leaving only the effect of temperature, thus indicating that differences in size at maturity are physiological adaptations in response to temperature.…”

“…Recent studies demonstrate that genetic adaptation can rescue populations from extinction in response to changing climatic conditions (Nussey et al , Bradshaw , Bradshaw and Holzapfel ), including rapid adaptation of increasing thermal tolerance (Geerts et al , Padfield et al ). Adaptive responses can prevent population decline if there is sufficient genetic variation and selection on heritable traits that increases fitness (Gomulkiewicz and Holt ).…”