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Great Barrier Reef

Great Barrier Reef

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Great Barrier Reef

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  1. Great Barrier Reef Threats and Sustainable Management

  2. Great Barrier Reef - Facts • Located off coast of Queensland, Australia • Largest collection of reefs in the world • Home to wide variety of fish, seagrasses, coral and other invertebrate species • GBR World Heritage Area is the largest in the world • Covers 30 million hectares

  3. GBR - Threats • Sedimentation and nutrient run-off • Commercial shipping • Commercial fishing • Crown of Thorns starfish • Global warming and coral bleaching

  4. GBR - Management • To preserve environment asset, reef must be carefully managed! • ‘Sustainable Management’ • The use of components of biological diversity in a way and at a rate that does not lead to the long term decline of biological diversity, thereby maintaining its potential to meet the needs and aspirations of present and future generations (Reichelt 2005, p. 7)

  5. Ningaloo Reef vs. GBR • Located off coast of Western Australia, near Exmouth • Extends over 260 kilometers • Are management plans from the GBR transferable to Ningaloo Reef?

  6. Terrestrial Inputs • Increased sedimentation is a result of human activity - land clearing, agriculture, urban development and industry • Riverine discharge dominated by flood events resulting from cyclones and monsoons • Estimated 15-28 tons of sediment deposited into the lagoon annually (Haynes 2001) • Largest discharges originate from the Burdekin and Fitzroy catchments

  7. The Great Barrier Reef and its catchments (Productivity Commission 2003)

  8. Terrestrial Inputs: Croplands and Grazing • Croplands responsible for the greatest impacts on sediment yield • Major crops: sugarcane, mangoes, bananas, lychees, tomatoes and cotton; sugarcane being the largest • Nitrogen and phosphorus are associated with fertiliser use, much of which is not absorbed and reaches the lagoon • Elevated nutrient levels promote phytoplankton growth, encourage macro algae blooms, and results in weakened coral skeletons • Cattle grazing - largest single use of land • Woodland and vegetation clearing contribute to run-off, overgrazing worsens erosion

  9. Terrestrial Inputs:Turbidity and Flood Plumes • Turbidity smothers corals and reduces light availability - adversely affects algae symbionts and seagrass beds • Freshwater plumes lower salinity causing stress on coral resulting in excessive mucous release and loss of zooxanthellae • Agricultural and urban storm and waste water carry unnatural quantities of heavy metals into lagoon • Potentially toxic and can cause growth and reproductive problems

  10. Terrestrial Inputs:Land Management • Avoid further clearing of coastal wetlands and riparian vegetation • Maintain fringing vegetation along stream and river banks • Improved farming and grazing practices will lead to improved water quality

  11. Terrestrial Inputs:Land Management CANEGROWERS Code of Practice for Sustainable Cane Growing: • Fertiliser application, soil management, native vegetation, irrigation and drainage • Green cane harvesting/trash blanketing - used by majority of cane growers in GBR catchment Grazing: • Spelling -Rotation of grazing pastures in order to maintain adequate ground cover

  12. Terrestrial Inputs:Ningaloo • Not currently under the same pressure as the GBR due to sparsely populated coastline • Unless restrictions are established, development of the coastal region and increases in population will lead Ningaloo to face similar threats

  13. Shipping in the GBR • Several major international shipping routes intersect the region • Cargo includes bauxite, alumina, manganese, iron ore, general container freight and oil • 2500 ships transit the GBR every year (Hugget et al. 2001)

  14. GBRWHA Principal Shipping Routes (Great Barrier Reef Marine Park Authority 1998)

  15. Impact of Shipping in the GBR Accidental Pollutants • result from grounding, collision or structural failure • oil or other noxious chemical • potential to cause serious environmental damage Operational Pollutants • result from day-to-day operation • waste products • e.g. oil, sewage, garbage and greenhouse emissions • antifoulants from hull paints • toxic to many marine organisms • introduce marine pests from ballast water

  16. Management of GBR Shipping • implemented through International Maritime Organisation (IMO) • MARPOL (73/78) • world's first Particularly Sensitive Sea Area in 1990 • compulsory pilotage • mandatory vessel reporting system (REEFREP) • REEFPLAN

  17. Future of GBR Shipping • grounding MV Carola, MV Peacock and MV New Reach demonstrate grounding potential is not eliminated • areas deemed high risk remote from established stockpiles of response equipment

  18. Ningaloo vs. GBR: Shipping Density

  19. Fisheries at the GBR • There are many important recreational and commercial fisheries at the GBR • Fisheries at the GBR: • Prawns, scallops, reef fish, rock lobster and sea cucumber

  20. Environmental Impacts of Fisheries • Fishing affects coral reefs directly and indirectly • Directly: • Reduces abundances of target and non-target species • Trawling and dredging destroy benthos • Indirectly: • Impacts on biological interactions • Affects the whole ecosystem

  21. Management of Fisheries in GBR • Management based on input restrictions eg. gear specifications, bag limits • Queensland DPI&F has effectively reduced fishing effort while maintaining catch levels • Zoning is used: • 6 different zones are used • 33% of the GBRMP is ‘no-take’ areas • This management was introduced to help depleted species recover

  22. Management of Fisheries in GBR • Sustainable management is currently occurring • Further improvements could be to change the focus from single species’ management to ecosystem based approaches

  23. Crown of Thorns Starfish • COTS widespread throughout GBR • Reddish brown echinoderm • Only venemous seastar • Typically 1ft. in diameter • Feeds on live hard coral – mainly branching tubular and staghorn coral (Aeropora) • Prefers to live in deep water along reef fronts

  24. How COTS Affect GBR • Individual COTS consumes 2-6 sq. m coral/year • Populations can grow faster then coral growth; leads to extensive loss of coral • Indirectly affects other organisms • Substantial coral deaths in the GBR since 1960’s • Since then many outbreaks have occurred as COTS have spread southwards along the coast via currents

  25. What causes COTS Outbreaks • Not known what the major cause of COT growth • Nutrients released via land runoff from human activities increase phytoplankton (important COTS food source) • Fishing and shell collecting has decreased COTS predators

  26. What is Being Done? • Extensive surveying of COTS have occurred in many sections of the GBR since 1985 • Most tourism sites have control systems in place for COTS • Divers inject deadly Soduim Sulphate solutions into COTS tissues -doesn’t affect other species • COTS exist in natural numbers in Ningaloo off Dampier; may be a threat in the future

  27. Global Warming - Threat • Elevated levels of greenhouse gases in the atmosphere  global climate change • The worlds oceans are a sink for atmospheric CO2 • GBR  elevated sea surface temperatures, caused by El Niño Southern Oscillation events

  28. Global Warming - Impact • Increased CO2 in water  dissolution and weakening of coral skeleton • Elevated SSTs  corals become ‘stressed’, expel some zooxanthellae, and are bleached • 1998 – worldwide mass coral bleaching event - Approximately 87% of the inshore reefs of the GBR were affected - Pacific, Indian Ocean, Red Sea, Persian Gulf, Mediterranean, Caribbean regions AND Ningaloo Reef

  29. Global Warming - Management • Cannot be managed on site – GBR • Global problem – global responsibility • Coral bleaching “canary to the coal mine” – is the destruction of coral reefs an indication of the damage that could be caused by global climate change in the future?

  30. GBR - Review

  31. Conclusions • Extremely important environmental feature under threat • Needs to be better managed • Possible with better administration and tougher legislation • Sustaining of the reef is a viable future!