Marine mammals are exposed to a wide range of human-related stressors, causing some potential detrimental health consequences. Killer whales and polar bears are among the most polluted animals on Earth. Killer whales are also in the spotlight of an intense whale tourism, while polar bears are at the forefront of climate change up in the Arctic. Alterations caused by pollutants, and stress related to climate change and whale tourism may thus interact, with possible combined effects associated with serious health consequences. Yet, our understanding in pollutants response in marine mammals remain poorly understood, and there is a lack of knowledge on the consequences when animals must cope with several stressors at the same time. To date, most of our knowledge relies on traditional approaches, which consist in examining the associations between the concentration of pollutants and specific health metrics. Although valuable, this approach suffers from important limitations to establish a mechanistic understanding and a causal link between pollutant exposure and health issues. In SLICE, we propose to complement this approach with the development of an alternative methodology through an ex vivo model. Practically, we will expose small tissue fractions to cocktail of pollutants and/or stress hormones (to mimic other stressors like climate change or whale tourism), and assess how the tissues react and what are the spill-over health related consequences. This is a novel cost-effective ethically sustainable approach to test responses to pollutants and stress separately or simultaneously, which is an important step forward to deepen our understanding of responses to multiple stressors in marine mammals. As charismatic animals, polar bears and whales have a strong potential to raise environmental awareness, and we will strive to communicate to a large audience the scientific knowledges generated by the project on threats of human stressors on marine mammals.
Marine mammals are relevant sentinels of oceans and human health. Arctic top predators, such as killer whales and polar bears, are among the most polluted species on Earth. They are also exposed to additional anthropogenic stressors such as climate change, resource limitations, habitat loss, and human coastal activities. However, cause-effect and mechanistic understanding in pollutants response in marine mammals remain poorly understood, and there is a lack of knowledge on the combined effects of multiple stressors. There is a need to develop alternative solutions and move from a reductionist perspective to a holistic and integrative strategy to understand the complex patterns of responses. In SLICE, we will combine experimental and field-based studies, together with the application of toxicogenomic approaches to advance the knowledge on toxicological responses to multiple stressors in killer whales and polar bears. We will develop an alternative methodology through an ex vivo adipose tissue slices model for both species and use it to characterize genome-wide transcriptional and lipidomics responses to pollutants and stress. This novel cost-effective ethically sustainable tool enables to test responses to pollutants and stress separately or simultaneously, which is an important step forward to deepen our understanding of toxicological responses to multiple stressors in marine mammals. In parallel, we will conduct correlative field studies to assess potential combined effects with pollutants and stress related to climate change for polar bears and whale tourism for killer whales. As charismatic megafauna, polar bears and whales have a strong potential to raise environmental awareness. Scientific knowledge generated by the project (and beyond) on threats of anthropogenic stressors will be communicated to the the scientific community, the public (focusing on young) and relevant stakeholders.