Mercury is a harmful substance that builds up in marine life, affecting the food chain and potentially harming humans. Scientists studied how climate changes and extreme events like floods impact mercury levels in phytoplankton in the southern Baltic Sea. They found that heavy rain and erosion can increase mercury accumulation in phytoplankton, especially when certain types of algae are abundant. After a cliff eroded, mercury levels in phytoplankton increased significantly. This shows that environmental changes can lead to higher mercury levels in marine organisms, which can eventually affect people who consume seafood.