Mangroves are salt-tolerant trees that provide a nesting area for a variety of birds. The submerged roots are a nursery and breeding ground for most of the marine life that migrates to the reef. Mangroves trap and produce nutrients for food and habitat, stabilize the shoreline by trapping debris and silt, and filter land-based pollutants. Seagrasses are flowering marine plants that are an important part of the food web. They provide food for turtles, manatees, and a variety of fish, and habitat for filter-feeding organisms and foraging sealife such as sea urchins and sea cucumbers.
Seagrasses are a nursery ground for pink shrimp, lobster, snapper and other sealife.
They filter the water by trapping sediments, release oxygen into the water and stabilize the ocean bottom with their roots. Diverse Many cultural and historical resources are found within the Lower Keys Region of the Florida Keys National Marine Sanctuary. Lighthouses were built along the Florida Keys prior to the Civil War to prevent shipwrecks along the reef. The Sand Key Lighthouse off Key West and the Sombrero Lighthouse off Marathon are still navigational aids. Numerous shipwrecks and the remains of Spanish galleons add to the variety of swimming, snorkeling, diving, photography and recreational boating activities within the sanctuary.