Abstract: Oceanic islands with reduced species richness provide an opportunity to investigate the emergence, maintenance and transmission of infectious diseases threatening wildlife. On Amsterdam Island, in the southern Indian Ocean, massive and recurrent mortality of the nestlings of Indian yellow-nosed albatross (Thalassarche carteri) has been attributed to avian cholera caused by Pasteurella multocida, a bacterial pathogen of likely human introduction. To understand the annual dynamics of pathogen prevalence, we measured the shedding of bacterial DNA by the albatrosses during four successive breeding seasons. The screening of 583 bird swabs by Real-Time PCR revealed an intense circulation of P. multocida during each study year, with a steady increase of infection prevalence across the breeding season. In the three years of highest pathogen prevalence, the epizootics were associated with massive die-offs of nestlings, inducing low annual fledging success (< 20%). These findings and developed PCR protocol have crucial applications for refining wildlife conservation plans aiming at controlling this disease.

Abstract: The present report is a synthesis of all studies conducted around the long-term ecological research (LTER) monitoring of introduced salmonid species in the sub Antarctic Kerguelen islands over the 2015- 2020 period, within the SALMEVOL-2 project. The monitoring encompasses the history of eight species, five of which are still present in Kerguelen, the data and collections spanning five decades and tenths of rivers. Based on this monitoring, but also thanks to various field experiments, we have undertaken to study the evolutionary ecology of these species, using the invasive Brown trout as flagship model, under the premise that the Kerguelen situation, where rivers were previously void of any fish species, could be an anticipation lab of the situation developing at the poles due to climate change. Our findings pertain to life history traits such as individual growth, migration between freshwater and marine ecosystems, microbiomes, but also proximal and ultimate mechanisms of adaptation in relation to the local environment. We also begin to investigate how the expanding metapopulation structure, resulting from multiple invasion events, may affect life history traits evolution.