Seagrasses are commonly found in shallow coastal marine locations. They are the only known flowering marine submerged grass. With nearly 60 species they form a diverse group and are found world-wide. They support complex food webs through both a physical and primary production role. Juveniles of many commercially important species of fish and invertebrates inhabit seagrass beds as a nursery area, others permanently over their entire lifecycle.

Florida seagrass bed. Taken by P. Gill, FKNMS, courtesy of NOAA.

"Over the last decade 290,000ha of seagrass loss have been documented. Projecting the rate to undocumented parts of the world, over 1.2million ha of seagrass have likely been lost." Short, F.T., & Wyllie-Echeverria, S. 2000.

The greatest threats to the world's seagrasses are humans. Urban pollution, agricultural runoff, industrial waste, terrestrial erosion, coastal development and dredging all contribute to their global decrease. Declining water quality is definitely their major threat, nutrient loading and sedimentation in particular. In the United States over 50 percent of the historical seagrass cover has been lost from Tampa Bay, 76 percent from the Mississippi Sound, and 90 percent from Galveston Bay.