Cadmium (Cd) is a common industrial and agricultural heavy metal found in the natural environment that disrupts the endocrine systems of vertebrates. Amphibians are particularly vulnerable to endocrine disruptors because of their aquatic habitats and permeable skin. Endocrine disruptors are known to negatively affect amphibian acoustic behavior, but whether and how the ubiquitous pollutant Cd impacts this crucial amphibian signaling system remains unknown. Male black-spotted frogs (Pelophylax nigromaculata) show phonotactic responses to female receptive calls by emitting advertisement calls and moving towards females during the mating season, essential for reproductive success. To study whether long-term (60 d) exposure to low Cd concentrations (10(-8), 10(-7) and 10(-6) M) affects male phonotaxis, we recorded male responses to female calls following Cd exposure during the breeding season. We found that Cd adversely affected advertisement call characteristics (call latency, call duration and call rate), the proportion of individuals that responded and the time to first movement of the male. These results indicate that long-term exposure to Cd at environmentally relevant concentrations alters phonotaxis in male P. nigromaculata.
Keywords: Cadmium; Calling behavior; Pelophylax nigromaculata; Phonotaxis.
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