Coral Disease Working Group
Coral reefs are under increasing stress from a number of causes, including climate warming, poor water quality and over fishing. Disease outbreaks cause not only coral loss, but they can result in significant changes in community structure, species diversity and reef-associated organisms. Coral diseases potentially impact both well-managed and unmanaged reefs indiscriminately. However, strategies for dealing with disease outbreaks are currently non-existent. The increasing frequency with which diseases influence and alter reef communities means they must be considered and incorporated into management plans.
Background
The CRTR Disease Working Group’s research will provide us with a greater understanding of the ways in which coral diseases can alter reef function and the conditions under which outbreaks may occur.
Global impact of coral disease
Coral disease stands out as a primary factor in the deterioration of many coral reefs with preliminary surveys indicating significant and damaging new diseases are now beginning to appear.
The CRTR Program Disease Working Group is conducting a global coral disease census across 24 high priority sites. This major assessment is designed to catalogue syndromes for the first time, and reveal whether disease outbreaks are correlated with climate warming anomalies.
In each location the impact and prevalence of coral disease is being measured.
Global warming and anthropogenic inputs
Increases in disease following warming events may be because corals have lower ability to fight disease while under temperature stress, or because bacteria are more virulent. While connections between poor water quality (nutrient loading and sedimentation) and disease are of increasing concern, evidence of direct links and synergistic effects are limited.
The CRTR Program Disease Working Group is measuring nitrogen and sediment loading at key research sites. The team will use molecular and enzymatic techniques to assess differences in microbial communities - in coral mucus, water and sediment between sites with different loadings, and between healthy and bleached corals. There will also be an evaluation of climate and anthropogenic influences on changes within microbial communities.
The causes, reservoirs and vectors of corals disease
Current research on disease reservoirs and vectors is hampered by a lack of knowledge of the pathogens causing the majority of coral diseases. To date there are only five coral diseases for which the microbial cause is known.
The Disease Working Group is developing a suite of techniques to facilitate the identification of pathogens in coral. Because only a small percentage of bacteria in nature are culturable, the identity and source of pathogens will be confirmed using various molecular fingerprinting techniques. Eventually a micro-array chip of global coral disease will be developed.
Coral resistance to disease
The microbial communities associated with coral are very complex, existing both inside the coral animal and in the surface mucous layers (SML). These normal communities protect the coral from disease. When the community structure changes, corals may become more susceptible to disease. Both bleaching and disease appear to change the microbial community profiles in the SML.
The goal of the Disease Working Group’s immunological work is to develop assays to determine general antimicrobial activity. Once resistant compounds are identified, they will be incorporated into a chip of biomarkers for stress. Field sampling will eventually allow the team to quantify and estimate the response of corals to different experimental treatments of enhanced nutrients and temperature, and map the spatial extent and variation of disease resistance in the field.
Our Research
Research Activities
Over the last 20 years, unprecedented increases in disease on coral reefs have contributed significantly to coral reef degradation. Disease-related damage of coral reefs has been well documented in the Caribbean, but recent observations of coral disease in other regions of the world are just beginning. Disease occurrence in these other regions may be a potential harbinger for further outbreaks and impacts associated with increasing climate warming.
The Disease Working Group is targeting investigations to address the causes of this rapid emergence of coral disease, to understand the impacts of the problem and to develop tools and responses that can be used for management.
Research Update
The Disease Working Group has answered many pressing questions including which disease syndromes are infections; which Centres of Excellence involved in the CRTR Program have the largest coral disease problems; which Centres of Excellence would be the most suitable for identifying local factors that might impact on disease; and whether climate factors would affect coral disease levels.
Impact of fish farms
As part of its study of the impact of local environmental factors on coral health, the Group has found that the fish pens in Bolinao Bay (Philippines) have a strong influence on the bacteria population, nutrient input, primary production and the patterns of energy and carbon flux in the surrounding waters. Researchers are working to identity specific bacteria from fish farms that reside on the surface of reef corals, and whether aquaculture plays a role as an incubator, conveyor and facilitator of disease into natural populations.
Disease in a warming ocean
The Group has made significant discoveries in the Caribbean and Australia regarding the potential impacts of heat stress, associated with climate warming events, on the outbreak of coral disease. In collaboration with the Remote Sensing Working Group it is developing new models to predict disease outbreaks using satellite monitoring data. The models use predicted sea temperature data and can identify the potential efficacy of various management strategies for future scenarios.
Other causes of coral disease
The Group continues to survey the prevalence of coral disease in Caribbean, Yucatan and Australian coral reefs, and is making progress in determining agents that cause coral disease such as skeletal eroding band, brown band and white syndrome.
Tools for Management
The Disease Working Group has developed important new tools for coral reef managers and researchers across the Western Atlantic and the Indo-Pacific to identify and address coral disease – the Coral Disease Handbook: Guidelines for Assessment, Monitoring and Management and two sets of underwater identification cards. These will be launched at the 11th International Coral Reef Symposium in July 2008.
Handbook
Designed for reef managers by international experts in coral disease, the Handbook outlines procedures for describing indicators, measuring impacts, monitoring outbreaks, assessing causes, and managing reefs to minimize losses due to disease. This handbook helps managers not only to document and manage disease on their reefs, but also enables them to contribute to our scientific understanding of this grave and increasing threat.
Underwater Cards Caribbean
These Underwater Cards for assessing the health of coral reefs have been designed so that scientific, professional and recreational divers can all assist with gathering information on the occurrence of coral reef diseases in the Caribbean. These cards will assist in the identification and monitoring of diseases in Caribbean coral and other reef organisms.
Underwater Cards Indo-Pacific
These Underwater Cards for assessing the health of coral reefs have been designed so that scientific, professional and recreational divers can all assist with gathering information on the occurrence of coral reef diseases in the Indo-Pacific. These cards will assist in the identification and monitoring of diseases in Indo-Pacific corals and other reef organisms.
Who we are
Working Group Members
- Working Group members bring international expertise and experience to this targeted research.
Project Partners
- Working Group partners bring capacity to this research endeavour.
Links
- IMAGES: Coral Disease Working Group
Contact
CRTR Program Disease Working Group:
Chair: Dr C Drew Harvell
Cornell University
Co-chair: Dr Garriet W Smith
University of South Carolina
Project Executing Agency:
Global Coral Reef Targeted Research and Capacity Building for Management Program
The University of Queensland
Brisbane QLD 4072
Australia
Tel: +61 7 3346 9942
Fax: +61 7 3365 4755
Email:
Information Resources
- Poster: CRTR Program Disease Working Group [download]
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Brochure: CRTR Program Summary [download]
- Research Update, July 2008 [download]
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In 2007 the Oceanography Society published a feature article by the CRTR Disease Working Group:
- Coral Disease, Environmental Drivers, and the Balance between Coral and Microbial Associates [download full article 2.3MB (with permission, Oceanography Society)]
- Coral Disease, Environmental Drivers, and the Balance between Coral and Microbial Associates [download summary text 30kB]
- Coral Disease Handbook: Guidelines for Assessment, Monitoring and Management and two sets of underwater identification cards [More] [Order Handbook, Caribbbean cards, Indo-Pacific cards online]