Thrice as easy to catch! Copper and temperature modulate predator‐prey interactions in larval dragonflies and anurans

Abstract

Abstract. Amphibians are important indicators of environmental health, and their populations are in worldwide decline. The causes of these declines are diverse and not well understood. In some cases multiple stressors and complex causal mechanisms have been identified. Experimental studies have shown that contaminants can cause the failure of Lithobates sylvaticus tadpoles to initiate predator avoidance behaviors, potentially leading to increased tadpole capture and injury. Copper is a contaminant known to negatively affect amphibians and other aquatic organisms at sub-lethal levels. Mining waste, certain pesticides, vehicle exhaust and brake pad dust are sources of copper, which can enter hydrologic systems through runoff. Additionally, temperature is known to influence predator-prey interactions of ectotherms and is predicted to rise in some areas as climate changes. We examined how copper and temperature affected behavior and predation dynamics between an odonate predator (Aeshna sitchensis) and larval L. sylvaticus prey. We found that sublethal concentrations of copper near the analytical detection limits for this element (1.85 lg Cu/L) significantly reduced tadpole and odonate activity. Above-average temperatures (228C) significantly increased tadpole activity and decreased dragonfly activity, compared with ambienttemperature treatments (178C). These behavioral responses culminated in an approximately three-fold increase in the number of dragonfly attacks on tadpoles in the elevated-temperature, copper-exposed treatments. We suggest that increased concentrations of dissolved copper and elevated water temperatures are harmful to amphibian prey through maladaptive behavioral responses in the presence of predators.

Consequences of dam‐altered thermal regimes for a riverine herbivore's digestive efficiency, growth and vulnerability to predation

“…This result is contrary to expectations based on short-term behavioural and modelling studies (Anderson, Kiesecker, Chivers, & Blaustein, 2001;Hayden et al, 2015) that survival might be low at higher temperatures because predator attack rates and capture success increase as tadpoles become more active in warm water. This result is contrary to expectations based on short-term behavioural and modelling studies (Anderson, Kiesecker, Chivers, & Blaustein, 2001;Hayden et al, 2015) that survival might be low at higher temperatures because predator attack rates and capture success increase as tadpoles become more active in warm water.…”

Stormwater wetlands can function as ecological traps for urban frogs

“…], copper in combination with elevated temperatures [Hayden et al. ]). This interesting trend and the fitness impacts of these altered behaviors warrants further investigation.…”

“…Predator avoidance was negatively correlated with levels of the heavy metal quotient. Copper, lead, and zinc were the three metals most correlated with the heavy metal quotient, and all three can affect predator avoidance of frogs (lead and zinc [Lefcort et al 1998], copper in combination with elevated temperatures [Hayden et al 2015]). This interesting trend and the fitness impacts of these altered behaviors warrants further investigation.…”

Protectiveness of Cu water quality criteria against impairment of behavior and chemo/mechanosensory responses: An update

“…That case of underprotectiveness was related to impairment of attraction of rusty crayfish to a food odor in water that contained 6.3 μg Cu/L (Lahman et al ). No underprotectiveness would have occurred in the studies with wood frogs (Reeves et al ; Hayden et al ), 3 cladocerans ( D. pulex in Hunter and Pyle ; D. magna in Simbeya et al ; Daphnia pulicaria in DeMille et al ), a larval dragonfly ( Aeshna sitchensis in Hayden et al ), and another study with rusty crayfish (Lahman and Moore ). The behavioral endpoint in the latter rusty crayfish study was decreased success in orienting toward a food odor at 428 μg Cu/L.…”