The Coral Disease Working Group is targeting investigations to address what has promoted the rapid emergence of coral disease which has been seen at unprecedented levels over the last 20 years; to understand this emergent problem; and to develop tools and responses that can be used for its management.
The Disease Working Group aims to fill critical information gaps about coral reef disease, build capacity internationally, and develop situations for managing and conserving reef ecosystems.
Major areas of focus for coral disease are:
- Global impact
- Global warming and human impact
- Causes, reservoirs and vectors
- Disease resistance
- Capacity building
Global impact of coral disease
Coral disease stands out as a primary factor in the deterioration of many coral reefs with surveys indicating significant and damaging new diseases are beginning to appear.
The Coral 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 human impact
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 Coral 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.
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 Coral 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 able to be cultured, 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 Coral 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.