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Seagrass Decline in Southern Australia

Healthy seagrass provides benefits to animals, plants and people.

The seagrass beds of Southern Australia provide habitat for many marine animals - they are known to be vital nursery areas for young fish. Seagrass beds also stabilise the seafloor by reducing the scouring effects of wave action and by trapping suspended particles.

Australia has the highest diversity of seagrasses in the world. Its temperate waters are known to have the oceans' largest areas of seagrass.

These unique temperate seagrass beds are under constant threat. Increased nutrient run-off from farm land, stormwater drains and sewage disposal devices can cause algal blooms - these can smother and eventually kill the seagrass. Sediments washing into the sea cloud the water, reducing the light necessary for the plants to grow. Increased nutrient run off and sedimentation have both been linked to massive die-back of seagrasses in New South Wales and Victoria. In Western Port Bay, Victoria, around 85% of the total biomass of seagrass has been lost over time.

The loss of seagrass has direct consequences for fishing industries, as many commercially important fish species spend the first few years of their lives living in seagrass beds. Once lost from an area, seagrasses do not readily recover. Australian marine biologists are mapping and studying seagrass beds so that they can further understand their importance and vulnerability.


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