Amphibian vocalizations: novel ecotoxicological bioindicators

TRUDEAU V.L.; ZHANG S; FARMER E; SALGADO COSTA C.; NATALE G. S.

Quebec

Workshop; CANADIAN ECOTOXICITY WORKSHOP; 2019

The vocalizations of male frogs and toads are critical forattracting mates and reproducing. Consequently, disruptionof such vocalizations by pollutants have been of concern sinceRachel Carson?s 1962 book ?Silent Spring?. Two case studiesof disrupted amphibian vocalization will be presented. Adultmale Silurana (Xenopus) tropicalis were exposed to controlconditions or a commercial mixture of naphthenic acids(NAs), an industrial contaminant from petroleum. Matingcalls were induced by injection of human chorionicgonadotropin (an analog of luteinizing hormone) andrecorded using underwater microphones. The NAs reduced orcompletely inhibited calling. We also studiedpremetamorphic tadpoles of Ceratophrys ornata (Argenrinianhorned frog), the first vertebrate known to vocalize as larvae.Sounds are emitted during conspecific interactions and whentouched to experimentally simulate an interaction, perhapsto avoid siblicide in this highly aggressive, carnivorous, andcannibalistic species. Exposure to the acetylcholinesteraseinhibitor chlorpyriphos (CPF; insecticide) disrupted thisunique behaviour. In addition to standard ecotoxicologicalendpoints in C. ornata tadpoles (mortality, swimming,abnormalities and growth inhibition), we show that soundproduction is extremely sensitive to water-borne CPF. Forboth examples, potential mechanisms of disruption will bediscussed.