Adverse effects of chronic copper exposure in larval northern leopard frogs (Rana pipiens)

Abstract

Northern leopard frogs (Rana pipiens) were exposed to environmentally relevant concentrations of copper in water (control and 5, 25, and 100 microg/L, as CuSO4) in a static renewal system for 154 d from posthatch stage to metamorphosis. After 10 d of copper exposure (from Gosner stages 19-25), survival of tadpoles was not significantly different between treatments (averages range from 96.7 to 99.3%), but a significantly higher incidence of deformities (p < 0.05) was observed in the 100-microg/L treatment. Tadpole growth rate was decreased in the 25- and 100-microg/L treatments relative to controls. Tadpole survival, swimming performance, percent metamorphosis, time to metamorphosis, and survival during and time required for tail resorption were also negatively affected in the 100-microg/L treatment. Copper concentrations in tadpole tissues ranged from 46.5 to 769.5 mg/ kg dry mass and were positively related to copper concentrations in the water. In conclusion, copper was shown to affect development, growth, survival, and behavior in larval northern leopard frogs at ecologically relevant concentrations. The existing U.S. Environmental Protection Agency freshwater-quality chronic criterion for copper appears to be protective for larval Rana pipiens.

Twice as easy to catch? A toxicant and a predator cue cause additive reductions in larval amphibian activity

“…Nevertheless, long-term reductions in activity as a result of either Cu (Redick andLa Point 2004, Chen et al 2007) or predators (Benard 2004, Relyea 2007 can result in a reduction in time spent foraging, resulting in smaller size or a longer time to metamorphosis over the course of a season (reviewed in Relyea 2007). These growth reductions or developmental delays may be due to either reduced foraging or higher metabolic costs of responding to toxicant or predator stress (Chen et al 2007, Relyea 2007. Copper in particular has been shown to cause lethargy, loss of equilibrium, apparent loss of appetite, reductions in growth, deformities, delayed metamorphosis, and mortality, but at concentrations at least 3-20 times higher than we tested here (Horne and Dunson 1995, Redick and La Point 2004, Chen et al 2007.…”

“…These growth reductions or developmental delays may be due to either reduced foraging or higher metabolic costs of responding to toxicant or predator stress (Chen et al 2007, Relyea 2007. Copper in particular has been shown to cause lethargy, loss of equilibrium, apparent loss of appetite, reductions in growth, deformities, delayed metamorphosis, and mortality, but at concentrations at least 3-20 times higher than we tested here (Horne and Dunson 1995, Redick and La Point 2004, Chen et al 2007.…”

“…Whereas short term activity reduction in response to predators has a clear risk-reduction benefit (Skelly 1994), short term activity reduction due to Cu has no fitness benefit, rather it is likely to just limit foraging and growth (Chen et al 2007). Long term activity reduction from Cu exposure could increase the time it takes for tadpoles to grow beyond the gape-limitation of the odonate predators in these systems, lengthening the time during which tadpoles risk predator attack (Urban 2007b).…”

“…Cu is a trace element essential for biochemical activities and enzyme function, but concentrations surpassing biological requirements can be toxic to aquatic life including amphibians (Eisler 1998, Chen et al 2007). Cu impairs ion exchange at the gill and interferes with osmoregulation (Eisler 1998).…”

Copper toxicity for Scinax ruber and Rhinella granulosa (Amphibia: Anura) of the Amazon: Potential of Biotic Ligand Model to predict toxicity in urban streams

“…Frogs are particularly susceptible to the effects of transition metals whose absorption is facilitated by their permeable skin. Tadpoles exposed to high concentrations of metals may present malformations, lower swimming performance and survival rate, longer metamorphosis time and changes in growth (Chen et al 2007;Garcia-Munõz et al 2009;Lance et al 2013).…”