Influence of Sea Grasses on the Productivity of Coastal Lagoons

Wood, E.J.; Odum, W.; Zieman, J.

Sea grasses in coastal lagoons act in several ways to control or modify the ecosystem. 1. They act as food for a very limited number of organisms such as the parrotfishes, surgeon fishes, Australian garfishes, the Queen conch, sea urchins, and some nudi branchs. The green sea turtle formerly grazed heavily on the turtle grass, hence the name. It has been found, however, that certain urchins grind up the sea grasses but do not appear to digest them, and this may well apply to other animals which appear to graze on them. 2. They serve as hosts for large number of epiphytes which are grazed extensively for example by the mullets. These epiphytes may be comparable in biomass with the sea grasses themselves. 3. They provide large quantities of detrital material which serves as food for certain animal species and for microbes which in turn are used as food by larger animals. 4. They provide organic matter to initiate sulfate reduction and an active sulfur cycle. 5. They bind the sediments and prevent erosion. This also preserves the microbial flora of the sediment and the sediment-water interface. 6. They tend to collect organic and inorganic material by slowing down current and stabilizing the sediments. 7. The sea grasses have a rapid rate of growth (up to 9 mm per day, average 2 to 4 mm per day) and produce between 2.2 and 10 gm of dry leaf per m^2 per day.

Influence of Sea Grasses on the Productivity of Coastal Lagoons

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