Abstract
AbstractNearly all aquatic ecosystems are affected by sublethal levels of anthropogenic chemical contamination, but other agents of large‐scale anthropogenic disruption of ecosystems have received more attention. Consequently, ecologists do not fully appreciate how sublethal contaminant exposure affects ecosystems. Sublethal contaminants can affect ecological systems directly via their impacts on an organism's fitness or indirectly by changing the strengths of species interactions. This study investigated how an emerging class of contaminants—pharmaceuticals and personal care products (PPCPs)—influences food webs by affecting the biology of organisms and by interfering with predator–prey interactions. Specifically, we investigated how three common PPCPs—caffeine, DEET (N, N‐diethyl‐meta‐toluamide), and triclosan—affect the strength of the interaction between a common mosquito predator (i.e., mosquito fish) and mosquito larvae as well as how these PPCPS affect mosquito survival, life history traits, and oviposition site choices. We found that all three PPCPs, individually and combined as a mixture, reduced predator consumption rates. Relative to a contaminant‐free control, the presence of predator cues reduced mosquito oviposition and larval abundance for all PPCP treatments except for DEET. Predator cues reduced mosquito adult emergence across PPCP treatments; however, mosquitoes that were exposed to caffeine did not emerge as adults even in the absence of predator cues. This study shows that the effects of PPCPs are diverse and can interact with mosquitoes and their predators in ways that cannot be predicted by their individual effects. In a contaminated world, ecologists need to better understand how sublethal concentrations of ubiquitous, biologically active pollutants might challenge what we think we know about how ecological systems function.
Highlights
Most aquatic ecosystems are affected by anthropogenic chemical contamination (Gessner and Tlili 2016), but other agents of large-scale anthropogenic disruption of ecosystems have received more attention (Bernhardt et al 2017)
Predation experiment In the absence of predators, all larvae survived in the caffeine, triclosan, control, and mixture treatment after 5 h, and nine out of the 10 larvae in the DEET treatment survived which suggests that the pharmaceuticals and personal care products (PPCPs) concentrations used in this study did not induce immediate mortality
Consumption of mosquito larvae by G. holbrooki was estimated by assuming a Type II functional response, according to Rogers random predator model, but allowing model parameters to vary by treatment (McCoy and Bolker 2008)
Summary
Most aquatic ecosystems are affected by anthropogenic chemical contamination (Gessner and Tlili 2016), but other agents of large-scale anthropogenic disruption of ecosystems (e.g., rising CO2 concentrations, biodiversity loss, nutrient pollution) have received more attention (Bernhardt et al 2017). Community structure and function is defined by trophic interactions which are influenced by the ability of individuals to detect and respond to one another and their surroundings (Laska and Wootton 1998). Abiotic factors, both synthetic and natural, frequently alter the interaction strength between species due to their impact on organismal detection and subsequent behavioral responses (Dunson and Travis 1991). Pesticides and metals can modify the ability for prey to detect or respond to predator cues which could disrupt trophic interactions (reviewed in Lu€rling and Scheffer 2007, Van Donk et al 2016)
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