The seafloor is the ocean’s foundation. Not so long ago, many scientists assumed the ocean floor was a vast plain, lifeless and without currents.

In the 1960s, scientists using early submersibles discovered that the ocean bottom is made up of familiar landscape features including great plains, deep canyons, mountain ridges and large seafloor hills, known as seamounts.

 Like land-based environments, life in the ocean is linked in ways that scientists are still coming to understand. Scientists are continuously learning about what happens to the rest of the ocean when one marine species is depleted or even disappears.

We do know, however, that while many fish and marine mammals travel thousands of miles around the world in their lives, others are only located in very limited areas and cannot survive the loss of their one special habitat.

U.S. waters (three to 200 miles off shore) cover 23 percent more area than the nation’s lands. Beneath the surface, the seafloor consists of a mosaic of habitats including smooth sand, mud, rocky ridges, deep-sea canyons and seamounts.

The incredible biodiversity of the oceans is especially concentrated around complex habitats of geologic structures (e.g., gravel, boulders, crevices, rock pinnacles, overhangs) and structures created by animals such as sea anemones, sponges and deep-sea coral. The marine food web and healthy marine ecosystems rely on diverse, relatively undisturbed, complex seafloor habitats.

Recent science has shown us that the tops of seamounts are actually often covered with thousands of years of coral growth. When such slow-growing animals are damaged or killed, the years, decades or centuries may be needed for the corals to recover.

Numerous studies have found that heavily trawled areas can suffer biodiversity crashes, particularly in complex habitats. Scientists do not yet fully understand how the trawling-induced impacts on one species will affect other species. The longer we allow bottom trawling to occur in these habitats, the more likely we will lose species that are important for the marine ecosystem, food, medicines, and technological advances.