Could popular conservation strategies for amphibians impair their skin microbiota?

Amphibians are currently the most endangered animal class on earth, with over one third of extant species threatened with extinction. One of the main drivers of their decline is the rapid spread of emerging skin diseases, caused by pathogens that suppress immune responses in their host. Resistance observed in some amphibians is mainly provided by their skin microbiota, with a few bacterial symbionts showing inhibitory activity against pathogens. However, the composition of amphibian skin bacterial assemblages is strongly dependent on the micro-organisms available in their surrounding environment. Considering that current management approaches used for amphibian conservation consist in translocating individuals (to sites with reduced threats, whether in captivity or in-situ), their microbiota is likely to change in composition throughout these events. Such reorganization might lead to dysbiosis of the skin microbiota and to the loss of symbionts implicated in disease resistance.
We investigated the impact of in-situ translocation (transfers between natural sites) on the skin microbiota of spotted salamander larvae. We found that the diversity and community structure of their microbiota were not significantly affected by the translocation event, but rather by the environment of development of the larvae prior to the experiment, thus suggesting a strong selection of skin microbial assemblages in early life stages. We advocate for the integration of the microbiota to amphibian conservation practices, and propose to focus on the conservation of the amphibian holobiont.