Managing Coral Disease
A coral disease response plan describes the steps for detecting, assessing, and responding to disease outbreaks. Because disease spread is at least partly dependent on transmission, managers may have options for directly intervening with the aim of reducing the severity or extent of impacts by controlling activities that increase risk of disease transfer. Disease can spread rapidly through a coral reef ecosystem, but disease outbreaks can also persist for months to years. This means that monitoring disease response may need to be sustained for many months or even years.
Like bleaching response plans, the type and scale of plan might vary greatly depending on your site and capacity. Recognizing and identifying coral diseases is critical for an effective disease response, and in many locations coral reef managers may need to rely on specialist expertise, or may implement a program to build capacity in this area. Fortunately, there are some excellent guides and tools ref to assist in the identification and management of coral disease.
Developing a Disease Response Plan
Planning before a disease outbreak occurs allows managers to quickly respond when the first signs of a disease outbreak are observed. It is critical to plan ahead for staffing, funding, communications, and monitoring. Having a plan in place will also help managers to gain credibility and political support with reef users and decision-makers. When developing disease response plans, it is important to include relevant stakeholders and partners, as well as senior officers from within the management organization. Clearly defining the roles and responsibilities of all organizations and individuals involved in a response is also crucial to the effectiveness of a plan.
There are some excellent examples of coral disease response plans, as well as other response plans that address multiple risks, including coral disease. Managers might also consider working with relevant scientists to develop coral disease outbreak risk forecasting tools, such as the one developed for the Great Barrier Reef.
Management Responses to Coral Disease Outbreaks
The nature of coral disease suggests that there may be potential to reduce the risk of an outbreak, or reduce the extent of an outbreak, through direct management interventions. It is important to determine the baseline conditions (i.e., what is normally present, and at what levels, in the coral community). Once managers determine “baseline” conditions, assessments can be made as to what represents above-normal disease levels and their potential for increased mortality. ref See the slides below for details on the techniques and strategies used by managers. Other management responses have been proposed, but most require further research and testing to determine their effectiveness and cost efficiency.
Direct management actions to alleviate infections may be possible in the case of a few pathogens.ref For example, there has been some success in controlling the spread of black band disease during warming anomalies by aspirating the band using large syringes or pumps. Clay or underwater epoxy putty can then be placed directly over the band ref to halt cyanobacterial growth left in the underlying coral skeleton. This technique has also been successfully attempted with yellow band disease, white plague and white band disease. If this approach is to be applied, it should be done with great care to avoid spreading cyanobacteria and other microorganisms from a diseased coral to surrounding corals.ref Surgical removal of diseased parts has also been used successfully to “treat” coral diseases.
Managers have restricted access to reef sites with high levels of disease with the aim of reducing risk of transmission by divers to unaffected sites. Another strategy involves controlling factors that exacerbate coral disease such as sedimentation and reduced water quality. ref During a disease event, managers may restrict the take of herbivorous fish so that algal grazers can keep algal blooms under control. ref Certain management actions that are specific to addressing coral disease will need to be implemented, such as biosecurity measures. Such measures include proper handling of diseased corals, reduction of movement between dive sites, and moving from non-infected sites to infected sites only. ref Suggested strategies to minimize damage from disease include culling and quarantine, isolation of disease vectors, removal of diseased parts, use of putty or concrete to cover diseased areas on coral, and use of antibiotic jelly on diseased corals. ref As scientists learn more about the causes and modes of transmission of coral disease, additional recommendations will be developed to reduce disease transmission and coral mortality.
There exists a network of dedicated and qualified scientists and managers who can be contacted for assistance, information, and advice. Members of the following two organizations can be contacted for information and can answer specific questions about coral disease:
- The Coral Disease and Health Consortium The Coral Disease and Health Consortium (CDHC) was created as a cooperative effort linking representatives from U.S. agencies involved in coral reef management. Currently, the group is involved in health assessments; outbreak responses within the U.S. and associated territories; research and development for diagnostics and pathology; an International Registry for Coral Pathology; and capacity building efforts that include training, technology transfer, and strategic research planning. Managers can contact the CDHC directly at: email@example.com, or either Dr. Andy Bruckner or Dr. Cheryl Woodley at NOAA. See Appendix 2 in the Coral Disease Handbook ref for their contact information.
- The Coral Reef Targeted Research Program, Coral Disease Working Group The Coral Disease Working Group (CDWG) is one of six working groups of the Global Environment Facility and World Bank’s Coral Reef Targeted Research (CRTR) program. The CDWG maintains collaborations in support of coral disease research at each of the CRTR’s four regional Centers of Excellence in the Philippines, Tanzania, Australia, and Mexico and each of these can provide information on sample collection and where to send samples. See Appendix 2 in the Coral Disease Handbook ref for a regional contact list of coral disease experts.