Land Use Impacts: Aquatic Ecology

  • seagrass

    Seagrass in Nantucket.

Human activities on land can have far-reaching consequences for life in the water. Fertilizers help crops and grass grow, but also release nitrogen and phosphorus into the water, where those nutrients fertilize the growth of algae. Massive algal blooms can block light, create low-oxygen “dead zones” and intensify coastal acidification, making life difficult or impossible for many fish and invertebrates people rely on.

Mercury pollution is another familiar example. Mercury works its way towards the water from coal burning, mining, industry and improperly discarded compact fluorescent light bulbs. On its way, microbes in the soil can transform it into methylmercury—the neurotoxin infamous for its presence in some seafood and particularly dangerous to developing embryos.

Besides directly releasing pollutants, land use can have more subtle impacts as well. Paved roads, parking lots and other impervious surfaces can exacerbate the flow of pollution into the water. Because these surfaces don’t absorb water, they make it easier for nutrients and other harmful chemicals to run off into streams during rainstorms. Manmade structures that help shorelines resist erosion, like riprap and bulkhead, can eliminate shallow-water habitat important to small fish and crabs. They can also harm seagrasses and other underwater plants because of the high wave energy they create. Without the food and habitat seagrasses provide, many other aquatic animals suffer, including juvenile blue crabs.

Scientists at SERC work to understand the problems and find solutions. They’re constantly searching for ways to use the land that benefit the watershed and the life within it, from living shorelines to chemicals that can trap mercury before it reaches the water. Browse through the projects below to find out more.