Seagrass beds are a major component of tropical marine ecosystems throughout the world, and it is the most diverse in the lagoonal systems that are associated with coral reefs. Seagrass beds serve a number of ecological functions.
They trap and help to stabilise bottom sediments to aid in increasing water clarity. Clearer waters improve light penetration, and consequently increase photosynthesis and rates of organic matter production. Sediment trapping contributes to coastal accretion, while sediment stabilisation helps prevent coastline erosion, especially under storm conditions. The removal of terrigenous (originating on land) sediment from lagoonal and estuarine water is a very important function of seagrasses, and may be essential in some areas to allow sediment-sensitive corals to exist on adjacent reefs.
Seagrasses have a nursery function as it supports more fish than bare areas. In addition, they may provide food and shelter for migrating pelagic species including birds and turtles which consume the plants directly. The beds have a relatively high rate of primary production; some are capable of binding 1,000g of carbon per square meter per year; or three to five times the near-shore average for phytoplankton, which is attributed to their dense root system that receives dissolved nitrogen from the muddy sediment full of anaerobic bacteria and at the same time stabilise sediment reducing potential sediment erosion in shallow waters.
Our seagrass beds and the greater intertidal flats are home to a variety of shellfish and other marine organisms and plant life that support one another. Seagrass beds are found on some islands only including Malolo and Malolo Lailai, Qalito, Tavua, Yanuya, Mana and the greater Nadi Bay area on mainland Viti Levu.