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.