During the summer of 2013 numerous maimed starfish were observed in the tidal pools of Olympic National Park (Washington State). The starfish could be found with lesions, missing appendages, or (in advanced cases) dead starfish were reduced to mush. As scientists began studying this possible marine health issue it became clear that a variety of Pacific starfish species appeared to suffer from this condition. Pycnopodia helianthoides or sunflower star, Pisaster ochraceus or ochre star, and Orthasterias koehleri or rainbow star were among the impacted species. As word spread it also became clear that starfish along the Pacific coast, from Alaska to California, were impacted. Similar episodes occurred in the past but not across such a vast area or with such high mortality rates.
The condition was named Sea Star Wasting Disease (SSWD) after the rapid wasting away of starfish who suffered from this disease. A cause for for this disease was still illusive with some suggesting it was the result of the Fukushima nuclear disaster in Japan, among other explanations. In December 2104 a group of scientists, led by Cornell University, published findings in the Proceeding of the National Academy of the United States of America (see link below) that identified the cause of SSWD was a densovirus, a single stranded virus that infects invertebrates.
The scientists also reported that the denovirus was present in Pacific waters in the past which begs the question-why now? There is a possible link to elevated water temperatures which may stress starfish thus causing them to be more vulnerable to the denovirus. Further research needs to be done to determine if there is truly a link or not. If there is a link it does not bode well for the future of Pacific starfish. The ecological impact of this disease is still unknown as well. Starfish are important predator species and some species are considered keystone species (http://education.nationalgeographic.com/encyclopedia/keystone-species/).This does not bode well for the Pacific coast as a whole.
The outbreak of SSWD in 2014 occurred so quickly that scientists were unprepared to address this issue straight away. Determining exact numbers of impacted starfish and the exact locations of impacted areas was difficult to establish with limited monitoring efforts for such a large geographical area. Currently the University of California in Santa Cruz is looking for citizen scientists to help them track outbreaks (see link below). More and more researchers are using citizen scientist platforms to include the public in their work. It is a win win for researchers and the public. Researchers can acquire needed data and the public has an active role in science. If you live in the area please consider participating.
About The Illustration:
A festive watercolor, gouache, and colored pencil drawing of starfish. I could not bring myself to draw disintegrating starfish. This image is available via Redbubble.
For More Information:
PNAS Paper: http://www.pnas.org/content/111/48/17278.full
University of CA, Santa Cruz SSWD Page and Citizen Science Program: http://www.eeb.ucsc.edu/pacificrockyintertidal/data-products/sea-star-wasting/index.html