Nitrogen runoff from farms is a major factor affecting the health of the Great Barrier Reef and is linked to outbreaks of the damaging crown-of-thorns starfish
Giant sea snails emit a scent that frightens the crown-of-thorns starfish
, the reef's chief predator.
The colourful coral faces a number of pressures including climate change, poor water quality from land-based runoff, the crown-of-thorns starfish
, which eat coral, and the impacts of coastal development and fishing.
The world's largest living organism has shrunk by about half over the past 30 years as a result of climate change, ocean acidification, pollution and crown-of-thorns starfish
, which prey on coral, the Independent reported.
They tracked populations of coral-eating crown-of-thorns starfish
and found that even low-intensity fishing of the starfish's predators enabled it to multiply significantly and destroy the reef.
They found even light levels of fishing caused populations of the coral-consuming crown-of-thorns starfish
to grow because this removed the starfish's predators, such as wrasse and triggerfish, from the sea.
Chemistry professor Daisuke Uemura told the 2000 International Chemical Congress of Pacific Basin Societies hosted by the American Chemical Society (ACS) that his team found that arachidonic acid and a-linolenic acid in sea urchins attract crown-of-thorns starfish
The crown-of-thorns starfish
made a big splash in the mid-1960s--and another in the early 1980s--when unusually large numbers of the species devastated live coral on Australia's Great Barrier Reef.
More marine tourism operators, community organisations and commercial reef users now have the opportunity to take part in the fight against crown-of-thorns starfish
infestations on the Great Barrier Reef.
In addition, climate change, crown-of-thorns starfish
and cyclones are also contributing factors.
It is also working to reduce outbreaks of the predatory coral-feeding crown-of-thorns starfish
The Great Barrier Reef was granted world heritage status in 1981, but has since faced numerous threats from coral bleaching to cyclones, runoff, Crown-of-thorns starfish
and commercial activity, the report added.