Tropical Sea Grass Ecosystems and Pollution

Zieman, J

Until recently, studies in the nearshore tropical environment have largely concentrated on the spectacular and complex coral reefs, and the dense, productive mangrove forests. However as marine science focuses on the living resources of the shallow, coastal seas, the vast beds of sea grasses bordering the tropical coastlines are being recognized as important resources. The significance of sea grasses in coastal ecosystems was documented early in the classic studies of Petersen (1918), but little further work on the ecological importance of these highly productive and easily studied areas followed until recently. Sea grasses are unique among submerged marine and estuarine plants due to the presence of an extensive root and rhizome system. Because of this system - high growth rates, and dense leaf development - sea grasses exert considerable influence over their environment. Wood et al. (1969) summarized the functions of sea grasses in estuarine and marine ecosystems as follows: (1) sea grasses have a rapid rate of growth and high organic productivity; (2) while alive, they act as food for only a limited number of organisms since the demise of the large sea turtles, but provide large quantities of detrital material which, along with its resident microbes, provide a majo1· food source for the estuarine ecosystem; (3) the leaves support large numbers of epiphytic organisms, which under favorable conditions, may be comparable in biomass to the sea grass leaf weight, and which are grazed extensively; ( 4) sea grasses provide organic matter which initiates sulfate reduction and maintains an active sulfur cycle in the estuarine sediments; (5) the dense leaves reduce the current velocity near the sediment surface and promote sedimentation of organic and inorganic particles; and (6) the roots and rhizomes bind the sediments and hinder erosion of the surface of the sediment…. Chapter sections include: Pollutants and stresses of tropical sea grasses, Dredging and filling, Eutrophication, Temperature and salinity, Wind and sea stress, Population explosions and overgrazing, Oil pollution, Metals, Physical disturbance and recolonization of sea grasses.

Tropical Sea Grass Ecosystems and Pollution

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