|
||||||||||||||
|
|
||||||||||||||
|
RUN-OFF CAUSES CONCERN FOR REEF19 November 2001 The amount of sediment and nutrients washed off the land and into the Great Barrier Reef World Heritage Area has risen considerably since European settlement, according to a new brochure released by the Cooperative Research Centre for the Great Barrier Reef World Heritage Area (CRC Reef) today, funded by the Myer Foundation and the Great Barrier Reef Research Foundation. Run-off is not likely to reach most of the reefs in the Great Barrier Reef World Heritage Area because they are more than 20 kilometres from the coast. The areas at highest risk from land-based run-off are between Port Douglas and Hinchinbrook Island, and between Bowen and Mackay, according to Dr Williams, Deputy CEO of CRC Reef. Widespread impacts of run-off will be gradual and difficult to detect. While there is currently little evidence of widespread deterioration of nearshore systems, there are some localised impacts from the increase in run-off. "We can't be sure about the extent of the impacts of increasing run-off on coral reefs because scientists have only been doing large-scale systematic studies in the Great Barrier Reef World Heritage Area for a relatively short time. So, we don't know what coral reefs looked like before European settlement and how much reef systems normally change over the long-term", says Dr Williams. "It is also difficult to separate the impacts of run-off on coral reefs from other disturbances such as cyclones, predation by crown-of-thorns starfish and coral bleaching. We know coral reefs can recover from these acute disturbances but the effect of chronic, sublethal stress, such as run-off, on reef systems is difficult to recognise and not well understood", says Dr Williams. "One of the greatest concerns is that the impacts of run-off will stress coastal systems and push them beyond a critical threshold so that they cannot recover from a major disturbance". "Because there is some uncertainty about the impact of run-off on the Great Barrier Reef World Heritage Area, we can't be sure that some of our inshore reefs are not close to their thresholds. This is good reason to take action now to reduce the amount of sediments, nutrients and pollutants that wash off the land and into the World Heritage Area to maintain the quality of reef waters and the health of biological communities." Significant improvements have been made in sustainable land use practices, but some practices continue to threaten the Great Barrier Reef World Heritage Area. No sector on its own is responsible - we must all help care for this Area. For more information or a copy of the brochure 'Land Use and the Great
Barrier Reef World Heritage Area' contact:
|
