Managing marine disease emergencies in an era of rapid change

Abstract

Infectious marine diseases can decimate populations and are increasing among some taxa due to global change and our increasing reliance on marine environments. Marine diseases become emergencies when significant ecological, economic or social impacts occur. We can prepare for and manage these emergencies through improved surveillance, and the development and iterative refinement of approaches to mitigate disease and its impacts. Improving surveillance requires fast, accurate diagnoses, forecasting disease risk and real-time monitoring of disease-promoting environmental conditions. Diversifying impact mitigation involves increasing host resilience to disease, reducing pathogen abundance and managing environmental factors that facilitate disease. Disease surveillance and mitigation can be adaptive if informed by research advances and catalysed by communication among observers, researchers and decision-makers using information-sharing platforms. Recent increases in the awareness of the threats posed by marine diseases may lead to policy frameworks that facilitate the responses and management that marine disease emergencies require.

Keywords: adaptive management; environmental law; impact mitigation; marine disease; response plan; surveillance.

Figure 1.

Marine diseases classifiable as emergencies due to the scope and scale of ecological, economic and social impacts. (a) Sea star wasting disease, (b) eelgrass wasting disease, (c) shrimp white spot disease, (d) white plague disease in the Caribbean coral Dendrogyra cylindrus, (e) Vibrio parahaemolyticus and V. vulnificus infections in oysters and (f) epizootic shell disease in lobsters. Most of these as well as many other marine disease emergencies cause significant impacts in more than one category. (Online version in colour.)

Figure 2.

A framework for adaptively managing marine disease emergencies. Routine disease surveillance enables early detection of more diseases. A working group then determines whether the disease is an emergency, triggering responsive efforts to mitigate disease and downstream impacts. Surveillance tools and mitigation approaches are informed by research and catalysed by effective communication among researchers, managers and stakeholders. (Online version in colour.)

Figure 3.

Cetacean morbillivirus (CeMV) causes dolphin stranding and mortality. Identifying CeMV as the cause of a mortality event depends on: fresh tissues, trained responders (a), and available, equipped diagnostic laboratories. In 2013/2014 CeMV was detected by PCR, virus isolation and histology, which stains intensely brown where the virus is present (b). This rapid response effort was made possible under the US Marine Mammal Health and Stranding Program. Under future legislation, similar coordinated responses could be possible for diseases in other marine taxa. Photos courtesy of Virginia Aquarium & Marine Science Center (both) and David Rotstein (b). (Online version in colour.)

Figure 4.

Predictive tools developed for the coral disease white syndromes (WS) in Australia's Great Barrier Reef. Statistical analyses were used to relate sea surface temperature patterns in the winter (seasonal forecast (a)) and summer (near real-time risk assessment (b,c)) to WS prevalence during outbreak and non-outbreak years [28,29]. These web-accessible tools are monitored by managers and scientists and used to target response efforts. Forecasting and near real-time monitoring of disease-promoting conditions can increase vigilance and support for surveillance efforts, resulting in earlier disease detection. (Online version in colour.)

Figure 5.

Management of oysters in the eastern US to reduce the impacts of Perkinsus marinus (dermo) and Haplosporidium nelsoni (MSX) can target the host, the pathogen or the environment. Disease-resistant hosts are protected in sanctuaries from harvest to promote an increase in the frequency of resistant genotypes (a). Biosecurity management focuses on pathogen screening in aquacultured seed (viewed histologically here) to prevent disease introduction into new areas and exacerbation of disease where it occurs (b). Conserving and restoring three-dimensional reef habitat enhances growth, reproduction and recruitment of healthy oyster metapopulations (c). (Online version in colour.)

Figure 6.

How the proposed disease management framework improves the timing of disease detection and extent of impact mitigation. Currently, marine diseases are detected near or after their epidemic peak (a) and there is limited management of the disease outbreak or downstream ecological, economic or social and cultural impact. Diseases could be detected earlier with greater disease surveillance, which increases management opportunities, especially for mitigating downstream impacts (b). Diseases are best managed when surveillance programmes can include data-driven forecasting and predictive modelling, ensuring mitigation starts before the epidemic peak (c) (see also figure 4). (Online version in colour.)