Abstract

Sea star mortality in several genera including Pycnopodia and Pisaster was unusually high along the west coast of North America, from Alaska to southern California from September 2013–current (January 2014). The number of dead sea stars is estimated in the millions and the mortality rates in affected regions continue to be high (January 2014) with upwards of 100% mortality documented in certain sea star species.¹ A similar but smaller event also occurred along the east coast earlier in 2013. An international and multidisciplinary team of scientists at various institutions including, but not limited to, Cornell University, Wildlife Conservation Society, SeaDoc Society, Monterey Bay Aquarium, Vancouver Aquarium, Seattle Aquarium, USGS National Wildlife Health Center, and Northwest ZooPath, are participating in the ongoing efforts to determine the cause of this unusual wildlife mortality event. Captive and free-ranging sea stars of various species and states of health were collected in British Columbia, Washington, and California. Sea star samples were analyzed using a wide array of diagnostic techniques including cytology, microbiology utilizing bacterial and viral genomics, toxin analysis, water and sediment evaluation, histopathology using traditional and non-traditional polymer embedding techniques, and transmission and scanning electron microscopy. Over 1,200 potential bacterial pathogens and numerous animal-infecting viruses have been isolated from diseased sea star samples through microbiological genomics performed at Cornell University. Efforts to identify toxins as well as to fulfill Koch's postulates via inoculation of apparently healthy sea stars with material from wasted sea stars are underway to determine the suspected transmissibility of the wasting syndrome. The results of transmission and scanning electron microscopy by wildlife veterinary pathologists at the University of Connecticut and the Wildlife Conservation Society will be reviewed. Lastly, the challenges and importance of investigating a large-scale wildlife mortality event in a marine species with little previous baseline health data through the efforts of a large team of scientists will be discussed with the summary of current diagnostic results and future directions.

Acknowledgements

The authors would like to thank the dive community for their support monitoring sea star disease as well as collecting samples for analysis. The authors thank additional collaborators including Dr. Raimondi and Melissa Miner from the University of California, Santa Cruz; Dr. Benjamin Miner from Western Washington University; Dr. Drew Harvell, Cornell University.

* Presenting author

Literature Cited

1.  Sleeman Jonathan. Sea Star Mortality on the West Coast. USGS National Wildlife Health Center, Wildlife Health Bulletin. December, 2013. www.nwhc.usgs.gov/publications/wildlife_health_bulletins/WHB_2013-06_Sea_Stars.pdf