Abstract: Basal metabolic rate (BMR), the minimal energetic cost of living in endotherms, is known to be influenced by thyroid hormones (THs) which are known to stimulate in vitro oxygen consumption of tissues in birds and mammals. Several environmental contaminants may act on energy expenditure through their thyroid hormone-disrupting properties. However, the effect of contaminants on BMR is still poorly documented for wildlife. Here, we investigated the relationships between three groups of contaminants (organochlorines (OCs), perfluoroalkyl substances (PFASs), and mercury) with metabolic rate (MR), considered here as a proxy of BMR and also with circulating total THs (thyroxine (TT4) and triiodothyronine (TT3)) in Arctic breeding adult black-legged kittiwakes (Rissa tridactyla) from Svalbard, during the chick rearing period. Our results indicate a negative relationship between the sum of all detected chlordanes (∑CHLs) and MR in both sexes whereas perfluorotridecanoate (PFTrA) and MR were positively related in females only. MR was not associated with mercury. Additionally, levels of TT3 were negatively related to ∑CHLs but not to PFTrA. The findings from the present study indicate that some OCs (in both sexes) and some PFASs (only in females) could disrupt fine adjustment of BMR during reproduction in adult kittiwakes. Importantly, highly lipophilic OCs and highly proteinophilic PFASs appear, at least in females, to have the ability to disrupt the metabolic rate in an opposite way. Therefore, our study highlights the need for ecotoxicological studies to include a large variety of contaminants which can act in an antagonistic manner.

Abstract: In the current context of climate change, sea-surface temperature variation, sea level rise and latitudinal shifts of currents and hydrological fronts are expected to affect marine biodiversity of the sub-Antarctic Islands, particularly in coastal waters. Characterising the impacts of climate change on marine communities requires recording environmental modifications through the establishment of long-term monitoring. PROTEKER aims at the establishment of a submarine observatory consisting of multi-disciplinary research: oceanography, habitat mapping and species inventories, genetic, eco-physiological and trophic analyses. It also aims to provide scientific standards for the management of the Kerguelen Marine Reserve. Eighteen sampling sites of previous programs were revisited by scuba diving among which eight were selected for monitoring and were progressively equipped. ROV observations and beam trawling have also been conducted for contextualisation. These sites (Morbihan Bay (4), North (2) and South (2) coast) are monitored using photo/video surveys, temperature and salinity sensors, and settlement plots. Sessile communities collected on settlement plots will be characterised yearly through morphological and DNA techniques. Phylogeographical studies of target taxa are being conducted to improve our knowledge of endemicity and connectivity levels among sub-Antarctic islands.

Abstract: Results acquired over more than two decades now make it possible to outline the functioning of the pelagic ecosystem off the Kerguelen Islands. Although the structuring role of natural iron fertilization has been demonstrated both in terms of productivity and the structuring of pelagic communities, recent results raise questions about the paradigm of the coupling between carbon and silicon biogeochemical cycles in naturally iron-fertilized environments of the Southern Ocean. Similarly, new, recently published results highlight the role of biological processes, e.g. the partitioning of grazing between micro- and mesozooplankton, or the life cycles of primary producers (including senescence and resting spore formation) in the operation of the biological carbon pump. At the same time, several conceptual models have been developed to better describe the functioning of pelagic ecosystems with regards to the limiting nutritional factors of the first trophic levels. The synthesis of current data lays the foundation for the current functioning of the pelagic ecosystems surrounding the Kerguelen Archipelago while new ongoing and future studies, especially under the framework of the MOBYDICK Project, aim at achieving an in-depth understanding of the processes linking biogeochemistry and biodiversity in an end–to–end approach, i.e., from prokaryotes to apex predators.