Mapping marine habitats – Exploring and monitoring, from human impacts to climate change

Earth is our Blue Planet, covered with water. We started mapping the marine environment several decades ago, with increasingly sophisticated instruments mostly relying on acoustics. They have helped us discover mid-ocean ridges, hydrothermal vents, submarine canyons and rich habitats and ecosystems. We are increasingly using the oceans and the seabeds, harvesting resources like fish and hydrocarbons, increasing commercial and recreational shipping, but also measuring the effects of climate change and developing marine renewable energies. As we start mapping more places, in more detail, and monitoring human impacts on marine ecosystems, we are creating very large datasets, throwing challenges for data storage, long-term data access, reliable interpretation and comparison between regions and between times.
This keynote speech will present a personal perspective on the last decades, focusing on international projects covering nearly all oceans (except the Antarctic) and nearly all depths (except the Mariana Trench). The mapping of mid-ocean ridges is a good example of how sonars have improved in coverage and resolution over the years, helping us map volcanic chains, discover hydrothermal fields, and change our understanding of plate tectonics. I have used the same techniques to map tsunami-generating areas around Europe, better quantifying present and future risks and (at the other end of the scale), deep-sea shipwrecks. Multi-aspect sonars have proved essential to map buried objects, often related to toxic waste, and using sonars upside down, we can also monitor the impacts of marine renewable energies on their surrounding ecosystems. I will also present my collaborations on measuring soundscapes around the world, improving seismic mitigation, designing techniques to follow the evolution of fragile marine habitats in Europe and Canada, and assessing changes in Arctic ice. These studies remind us of how essential acoustics is, as well as how useful to monitoring and acting on human impacts and climate change.