Sea stars are an iconic coastal creature and found from the intertidal zone down to the abysmal depths. With over 1,500 species, they exist in subzero polar waters to warm tropical countries. Sea stars inspire and interest all types of people – from children rock-pooling to scientists and scuba divers.
Sadly, a recent epidemic has been affecting our beloved sea stars. The Sea Star Wasting Syndrome, as it’s been called, is a virulent disease that turns our stars of the coastline into a bacterial gooey pulp. The Sea Star Wasting Syndrome is causing the mass mortality of certain sea star species. “Sea stars go from “appearing normal” to becoming a pile of white bacteria and scattered skeletal bits in only a matter of a couple of weeks, possibly less than that”(1).
The sea star families with the highest mortality rate are:
- Sunflower star (Pycnopodia helianthoides)
- Mottled star (Evasterias troschelii)
- Giant pink star (Pisaster brevispinus)
- Ochre star aka purple star (Pisaster ochraceus)
- Morning sun star (Solaster dawsoni).
Also affected but on a lesser scale are:
- Vermillion star (Mediaster aequalis)
- Rainbow star (Orthasterias koehleri)
- Leather star (Dermasterias imbricata)
- Striped sun star (Solaster stimpsoni)
- Six-rayed stars (Leptasterias sp.).
The UCSC reports that observations of the Sea Star Wasting Syndrome have occurred on both the east and west coasts of the United States. There have been sightings on the west coast from Southeast Alaska down to Orange County, California. British Columbia, Canada, has also been heavily affected with over 10 species showing signs of the disease.
In March, 2013, Vashon Island in Puget Sound reported the first incident of Sea Star Wasting Disease. A long term monitoring site in Washington also reported diseased sea stars in June, and the situation seems to have escalated quickly from there. August and September saw more reports coming in from British Columbia, Canada, and Southeast Alaska.
These reports are filed by researchers from institutions such as: Long Marine Lab, Monterey Bay Aquarium Research Institute, Monterey Bay Aquarium, and Moss Landing Marine Laboratories. Recreational divers have also been reporting their sightings, alongside results from long-term monitoring sites up and down the coastline.
The Sea Star Wasting Syndrome is still an unsolved mystery. Scientists and researchers speculate that it may be a pathogen that has the ability to affect different species, but ultimately the underlying cause/s of the epidemic are not yet known. Increased sea temperatures have also been theorized to be a factor contributing to the die off, as sea stars are highly sensitive to temperature increase.
A widespread epidemic of this proportion has not been reported before. Similar outbreaks have occurred over the last 30 years, but never to this extent. Drew Harvell, a Cornell University professor who studies marine diseases said: “These kinds of events are sentinels of change. When you get an event like this, I think everybody will say it’s an extreme event and it’s pretty important to figure out what’s going on . . . Not knowing is scary . . . If a similar thing were happening to humans, the Centers for Disease Control and Prevention would commit an army of doctors and scientists to unraveling the mystery”(2).
Divers can report sightings and monitor the epidemic on the following websites:
http://www.vanaqua.org/act/research/sea-stars – Vancouver Aquarium Howe Sound Conservation and Research Team Mapping.
http://data.piscoweb.org/marine1/seastardisease.html – UCSC Pacific Rocky Intertidal Monitoring Map.
(1) Neil McDaniel – http://themarinedetective.com/2013/11/10/wasted-what-is-happening-to-the-sea-stars-of-the-ne-pacific/