 Ocean acidification is, in fact, the increase in acidity of the surface marine waters. This is mainly due to the increased emissions of CO2 by human activities that is partly taken up by the oceans. When I say partly, it's about 25% of the man-made CO2 that are taken up by the ocean. That means about 24 million tons daily that are taken up by the oceans. This CO2, once in the water, will be trapped, partly trapped in the waters but will be transformed in carbonic acid. And this carbonic acid will finally increase the acidity of the waters. So this increase in acidity in the water has a major effect on the chemistry of the water. And eventually, it is modifying the equilibrium of the carbonates. The carbonates are in fact the main building blocks that are used by many marine organisms to build their skeleton. So when you decrease the availability of these carbonates, that's what happens when you increase the acidity, the organisms can no longer have access to these carbonates to build their skeleton. And so it's reducing the skeleton. And many organisms depend on these skeletons to survive, to grow, to reproduce. And using some nuclear techniques, we can assess quite easily how these organisms are able to grow, are able to produce their skeleton, are able to build their skeleton under different acidity scenarios. And this can be done almost only thanks to nuclear applications, like the incorporation of calcium in the skeleton that is tracked using the radioactive calcium. Some very tiny organisms that are the base of many marine food chains are directly affected. Their life is based on the integrity of their skeleton. When they cannot build their skeleton, they die. And when they die, of course, the organisms that are feeding on them are dying as well. As soon as you are affecting the food chain, all the organisms feeding on other ones can potentially be affected. And the ultimate level of this food chain is man. And indeed, many communities in the world are relying heavily on seafood as main sources of protein. And when you decrease, well, you affect the seafood organisms, the food chains, you will affect, finally, the seafood sources for this population. And this is, of course, a direct impact on seafood security. One of the major purpose of our work is to assess the sensitivity and the resistance of marine organisms to ocean acidification. This is a global stressor. And so we need to know to have this information in order to propose some adaptation or mitigation strategies. It has, of course, a major impact on fisheries and aquaculture. And we have, for instance, to determine some species that are more resistant to this stressor to allow the reorienting some aquaculture or fisheries practices. But with the observation that are made nowadays in the marine environment and the information we have from the last 200, 250 years, the scientists can predict that the acidity is increasing a lot at a rate that is the fastest that was ever observed. And we know now that by the end of 2100, the acidity will have increased by 150% in the oceans.