Contaminant-induced behavioural changes in amphibians: A meta-analysis

Environmental contamination contributes to the threatened status of many amphibian populations. Many contaminants alter behaviour at concentrations commonly experienced in the environment, with negative consequences for individual fitness, populations and communities. A comprehensive, quantitative evaluation of the behavioural sensitivity of amphibians is warranted to better understand the population-level and resultant ecological impacts of contaminants. We conducted a systematic review and meta-analysis evaluating behavioural changes following exposure to contaminants. Most studies were conducted in North America and Europe on larval stages, and 64% of the 116 studies focussed on the effects of insecticides. We found that a suite of contaminants influence a wide range of behaviours in amphibians, with insecticides typically invoking the strongest responses. In particular, insecticides increased rates of abnormal swimming, and reduced escape responses to simulated predator attacks. Our analysis identified five key needs for future research, in particular the need: (1) for researchers to provide more details of experimental protocols and results (2) to develop a strong research base for future quantitative reviews, (3) to broaden the suite of contaminants tested, (4) to better study and thus understand the effects of multiple stressors, and (5) to establish the ecological importance of behavioural alterations. Behavioural endpoints provide useful sub-lethal indicators of how contaminants influence amphibians, and coupled with standard ecotoxicological endpoints, can provide valuable information for population models assessing the broader ecological consequences of environmental contamination.