What is seagrass
Seagrasses form the 'meadows' of coastal waters. They are vascular,
flowering plants with roots, making them quite different from
seaweed, which is an alga. Their large root system is essential
for the uptake of nutrients and for anchoring them to the sand.
It is estimated that seagrasses cover 5000 km² of the sheltered
waters of Gulf St Vincent. The dominant seagrasses are ribbon-weed
(Posidonia spp.) and wire-weed (Amphibolis spp.)
and in the shallower regions, paddle-weed (Halophila spp.)
and eel-grass (Zostera and Heterozostera spp.).
Seagrass provides habitat for a large variety of marine animals,
including fish, and stabilises the sand, reducing erosion. Seagrasses
also reduce wave energy, which can help to stop coastal damage
during storms.
What is happening to seagrass
Seagrass is commonly lost when nutrient levels in the water increase.
These nutrients cause a large number of epiphytes to grow on the
seagrass leaves, causing them to become too heavy and to break
off. The nutrients also encourage more microscopic algae to grow
in the water, reducing the amount of light getting to the seagrass,
particularly in the deeper regions.
Over 50km² of seagrass have been lost from the Adelaide
metropolitan coastline. This has been attributed to the effects
of discharges such as sewage effluent and sludge and also stormwater.
Reports
Seagrass Coverage Report (952KB
PDF)
Links
Adelaide Coastal Waters Study
Coast
& Marine Branch of the Department of Environment & Heritage
This page was last modified 21-06-2006
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