Coral Reefs: A Reef Resilience Toolkit Module

Management

Proving the cause of a disease is a difficult, lengthy process, beyond the scope of most managers and their laboratories or field stations. However, knowledge of the causal agent of a disease is not necessary in order to take management steps.

A first step is to develop working knowledge of the diseases and compromised health states present in a given management area (i.e., to know what is normally present, and at what levels, in the coral community). Once there is an understanding of ‘baseline’ conditions, assessments can be made as to what represents above normal disease levels and their potential for increased mortality.

Three important points should be kept in mind when managing for coral diseases:

1. Causes: Diseases can have many causes; some of these are infectious (such as bacteria, parasites, or viruses) and others are not (such as genetically-based or toxicant-induced disorders).
2. Signs: The typical sign of a diseased coral is a lesion, a manifestation of disease that may not provide any clue regarding causation.
3. Lesions: Some lesions in corals may have known causes that are not attributable to disease, though they result in the coral’s health being compromised. For example, fish bites and crown-of-thorns starfish feeding scars should be characterized as predation; lesions associated with breakages may be caused by storms or anchor damage and should be characterized as disturbance; and lesions caused by aggressive interactions between corals or between corals and other sessile organisms should be characterized as competition. All can lead to tears and breaks in the tissue and partial mortality, and can stress the host coral. In suspected disease cases, it is often impossible to determine the cause of the lesion (and, therefore, the cause of the disease) without additional laboratory or experimental efforts.

Resources

ICRI Guidance Materials