Abstract

Sea star wasting disease (SSWD) is associated with one of the largest marine wildlife die-offs ever recorded, killing millions of sea stars from Alaska to Mexico since the summer of 2013.¹ Over 20 species of sea stars have been affected by SSWD. Anecdotal reports suggested that enrofloxacin administered via intracoelomic injection (i.c.) was effective in treating SSWD in captive sea stars. Fifty-two sea stars from the five genera (Pycnopodia, Pisaster, Evasterias, Dermasterias, and Orthosterisas) all showing early signs of SSWD, were randomly assigned into a treatment group (n=26, enrofloxacin 5 mg/kg, i.c. q4 days) and a control group (n=26, saline 0.9%, i.c. q4 days) for a total of six treatments. Animals were monitored and graded for severity of lesions twice daily. The scores were not significantly different between groups throughout the study period. At day 20, after four treatments, the mortality rate was 100% and 77% in the control and treatment groups respectively and was not significantly different (p=0.55). At day 30, after six complete treatments, the mortality rate in the treatment group was 95% and there was no significant difference between the two groups (p=0.9). While enrofloxacin given intracoelomically at 10 mg/kg to sea stars results in high drug concentrations in the hemolymph of sea stars (J. Rosenburg, pers. comm.), administration of enrofloxacin by injection did not alter mortality rates significantly in captive sea stars affected by SSWD and is therefore not recommended for the treatment of this disease in commonly affected species.

Acknowledgments

The authors thank Dr. Martin Haulena of the Vancouver Aquarium and Dr. Michael Murray of the Monterey Bay Aquarium for their support and review of this project. The authors thank the Boeing Corporation for their generous support of Sea Star Wasting Disease research through a grant awarded to the Seattle Aquarium.

Literature Cited

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