Strategies for managing marine disease

Abstract

The incidence of emerging infectious diseases (EIDs) has increased in wildlife populations in recent years and is expected to continue to increase with global environmental change. Marine diseases are relatively understudied compared with terrestrial diseases but warrant parallel attention as they can disrupt ecosystems, cause economic loss, and threaten human livelihoods. Although there are many existing tools to combat the direct and indirect consequences of EIDs, these management strategies are often insufficient or ineffective in marine habitats compared with their terrestrial counterparts, often due to fundamental differences between marine and terrestrial systems. Here, we first illustrate how the marine environment and marine organism life histories present challenges and opportunities for wildlife disease management. We then assess the application of common disease management strategies to marine versus terrestrial systems to identify those that may be most effective for marine disease outbreak prevention, response, and recovery. Finally, we recommend multiple actions that will enable more successful management of marine wildlife disease emergencies in the future. These include prioritizing marine disease research and understanding its links to climate change, improving marine ecosystem health, forming better monitoring and response networks, developing marine veterinary medicine programs, and enacting policy that addresses marine and other wildlife diseases. Overall, we encourage a more proactive rather than reactive approach to marine wildlife disease management and emphasize that multidisciplinary collaborations are crucial to managing marine wildlife health.

Keywords: disease ecology; marine conservation; marine wildlife.

FIGURE 1

(a) A conceptual disease triangle, in which pathogen dynamics, host dynamics, and favorable environments intersect to create disease. (b) Management action reduces overlap of pathogen and host dynamics to reduce disease risk. For example, in Robinson et al., , targeted vaccination of monk seals (host) against canine distemper virus (pathogen) reduced host susceptibility and exposure to pathogens, ultimately reducing disease prevelance.

FIGURE 2

(a) The scale used to classify a given management strategy according to its utility in managing marine disease emergencies. A high score of 4 (green) indicates that the strategy is useful in most marine disease systems. 3 (yellow) indicates the strategy is potentially useful in most marine disease systems with more research and/or resources. 2 (orange) indicates the strategy is useful in some marine disease systems depending on the taxon or circumstances, and 1 (red) indicates the strategy is not useful in most marine disease systems. (b) Summary of management strategies and their utility score, according to color and scale in (a) in marine disease emergencies. Management strategies are grouped by the time frame during which they may be useful and the specificity to a given disease system in blue

FIGURE 3

Issues in marine disease management and accompanying recommendations. (a) The CHAMP Laboratory (Coral Health and Marine Probiotics) of University of North Carolina Wilmington applies probiotics to corals off the coast of Florida, USA to treat stony coral tissue loss disease. Photograph by Hunter Noren. (b) Mesocosm infection experiments of the mud crab, Eurypanopeus depressus by parasitic barnacle Loxothylacus panopaei enable incorporating mechanistic environmental response in epidemiological models (Gehman et al., 2018). Photograph by Alyssa Gehman. (c) Restoration and conservation of sea grass bed habitats, which can act as natural ecosystem filters (Lamb, van de Water, Bourne, Altier, Hein, et al., 2017). (d) Members of the PRIMED Network training volunteers to identify and report marine diseases using iNaturalist. Photograph by Sarah Gravem. (e) A veterinary medicine student at Oregon State University treating a wound on an injured sea lion. Photograph Robyn Cates. (f) The Endangered Species Act is being used to help species recover from sea star wasting disease, yet there is no explicit policy managing wildlife disease. Photograph by Janna Nichols in Washington, USA