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Kelp Forests

4. Habitat Issues / Threats

Historical records suggest that some kelp forests are much reduced in areas in southern Australia. This is particularly true for forests of Giant Kelp in Tasmania. Various factors have been attributed to causing this decline including global warming and changing nutrient levels. Researchers are however largely at a loss to explain the extensive loss of giant and string kelps. .

In other places nutrients from land based sources such as sewage outfalls, stormwater runoff, or rain and groundwater coming form catchments contributes to the excessive growth of epiphytic algae that grow on the surface of the larger kelps. If this growth is beyond the capacity of grazers to remove them eventually the plants are unable to absorb sufficient light themselves to stay alive and die off.

Undaria pinnatifida
(image from http://crimp.marine.csiro.au)
Another threat to Australian algal communities is the arrival from other countries of other species that can grow at faster rates that native species and compete with them for space on rocky reefs. Undaria pinnatifida is a species cultivated widely in Japan and Korea for food where it is used as a sea vegetable called 'wakame'. Unfortunately this plant has become established on both the East Coast of Tasmania as well as recently spreading along the western shores of Port Phillip Bay. It is an aggressive coloniser that can replace native seaweeds and reduce the habitat available for other species.

Next -  What can we do to protect our kelp forests?   

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What can we do to protect our kelp forests?
Macrocystis pyrifera seaweed culture
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