Ribeiroia - Parasite-induced Malformations and Amphibian Conservation

Parasite-induced Malformations and Amphibian Conservation

Perhaps the most unexplored, complex and vital aspects of trematode-caused amphibian malformations are the population-level consequences. Do these parasites and the malformations they induce pose a conservation risk? While no direct evidence linking trematode deformities and amphibian population declines exists, there are legitimate reasons for concern (Johnson and McKenzie 2008). For instance, in multiple species of frogs and toads, laboratory studies show that even low levels of Ribeiroia infection can induce 30-95% mortality (see Johnson et al. 2010). Correspondingly, multi-year field studies show that in localities of high infection and malformations in metamorphosing frogs, <2% of amphibians returning to breed exhibit malformations, suggesting Ribeiroia infection and malformations have deleterious consequences for individual survival and fecundity (Johnson et al. 2001). In specific wetlands that have historically exhibited a high prevalence of infection and malformations, several amphibian species have notably declined or disappeared (see Johnson and McKenzie 2008 for review). In light of these data, and the increasing evidence that Ribeiroia infections are on the rise (Johnson and McKenzie 2008), it is prudent to treat Ribeiroia ondatrae as a threat to amphibian populations and diversity, particularly in combination with other stressors.