Management Concern: High    

Adequacy of Information: Moderate

Summary extracts from Outlook Report 2009

• Little is known about most symbiotic relationships
• One of the most significant symbioses is that between zooxanthellae and various host organisms, including hard corals, soft corals, anemones, sponges, flatworms and molluscs.  Zooxanthellae photosynthesise like other green plants, however up to 95 percent of the nutrients produced are used by the host organism.
• Coral bleaching is the breakdown of this symbiotic relationship with stress to the corals causing them to expel their zooxanthellae, thereby turning white.  This is likely to occur more frequently in the future as sea temperatures increase with climate change.
• Symbiodinium exists as a number of strains with different tolerances for temperature which may have implications for coral reefs in the face of climate change. It is likely that the relevant prevalence of strains will change in response to climate change.
• Increased concentrations of suspended sediments and agricultural chemicals are having significant effects inshore close to agricultural areas. Much continues to be done to improve water quality entering the Great Barrier Reef but it will be decades before the benefits are seen.

What do we know?

Relevant pages from Outlook Online include:

• Symbiosis in coral reefs
  
• Turtle barnacles
• Identity and diversity of coral endosymbionts
• Vulnerability of coral reefs of the Great Barrier Reef to climate change
  
• Projected vulnerabilities of components of the Great Barrier Reef ecosystem to climate change
• Differential susceptibilities of corals to bleaching 
  
• Coral reef bleaching: ecological perspectives (pre-1993)
  
• Climate change, coral bleaching and the future of the world's coral reefs
• 1997-98: Unprecedented thermal stress to coral reefs?
  
• Bleaching events in 1998 and 2002 
• Coral survival following bleaching  
• Scientific consensus statement on water quality in the Great Barrier Reef
  
• Reef exposure to river contaminants ecosystem risk index
  
• Catchment influence on the Great Barrier Reef
  
• Inshore Reef Health
  
• Water quality effects on hard coral richness
  
• Water quality effects on richness of phototrophic octocorals
  
• Water quality effects on richness of heterotrophic octocorals
  
• Water quality in the GBR - guidelines and current status
• Development intensification and water quality pressures on the Great Barrier Reef ecosystems
• River mouth monitoring - nutrient, sediment and pesticide loads
• Development intensification and water quality pressures on the Great Barrier Reef
• Great Barrier Reef exposure model: total suspended solids
• Inshore reef health - nutrient, sediment and pesticide loads
• Land-sourced pollutants and their impacts on water quality 
• Changes in algal, coral and fish assemblages along water quality gradients
  
• Rapid smothering of coral reef organisms by muddy marine snow
  
• Terrestrial run-off and its effects on reef ecology  
  
• Role of elevated organic carbon and microbial activity in coral mortality 

Existing policies and management actions

• Great Barrier Reef Marine Park Zoning Plan 2003
  
• Australian Government policy on climate change 
• Queensland Government climate change policies and strategies 
• Climate Change Action Plan 2007-2012
• Water Quality Guidelines for the Great Barrier Reef Marine Park (2009)
  
• Regional Water Quality Improvement Plans
  
• Reef Rescue Marine Monitoring Program
• Improving water quality
• Coastal ecosystem protection

Future management requirements

• Future management requirements in this area are being guided by ongoing assessment of emerging research outcomes and issues identified by the Great Barrier Reef Outlook Report 2009.

Defined research questions

• What are the key factors that lead to coral bleaching and how can these be predicted?
• What are the mechanisms behind bleaching resistance and resilience?
• To what extent do interactions, and any synergies, between local, regional, and global stressors influence coral bleaching response patterns, associated mortality, and the extent and rate of recovery?
• What will be the effects of climate change on microbial processes and symbioses?

Related information

• Current Research and Monitoring