Coral reefs and the marine organisms that live within and around them are at risk from exposure to the toxic substances within oil as well as smothering. Exposed sandy, gravel or cobbled beaches are usually cleaned by manual techniques. Although oil can soak into sand and gravel, few organisms live full-time in this habitat, so the risk to animal life or the food chain is less than in other habitats, such as tidal flats. Sheltered beaches have very little wave action to encourage natural dispersion. If timely cleanup efforts are not begun, oil may remain stranded on these beaches for years.
Tidal flats are broad, low-tide zones, usually containing rich plant, animal, and bird communities.
Deposited oil may seep into the muddy bottoms of these flats, creating potentially harmful effects on the ecology of the area. Salt marshes are found in sheltered waters in cold and temperate areas. They host a variety of plant, bird, and mammal life. Marsh vegetation, especially root systems, is easily damaged by fresh light oils. Mangrove forests are located in tropical regions and are home to a diversity of plant and animal life.