Tropical coastal ecosystems are among the most biodiverse areas on Earth. And they’re also on the front lines of effects caused by human activity. That’s why it’s becoming increasingly important, especially as human populations increase, to manage the impacts of runoff and wastewater that flow into the sea.Tropical coastal ecosystems are among the most biodiverse areas on Earth. And they’re also on the front lines of effects caused by human activity. That’s why it’s becoming increasingly important, especially as human populations increase, to manage the impacts of runoff and wastewater that flow into the sea.