At the end of summer 2013, it became apparent that an epidemic had spread through the extremely overpopulated sunflower sea star populations in Vancouver Harbour and Howe Sound. They appear to have simply fallen ill; thousands have died and disintegrated in shallow water where their numbers are most dense.
Diving biologists Neil McDaniel and Doug Swanston found sunflower sea stars collapsing around Defence Islands, up across from Porteau Cove. There, they found many sea stars wasting away, but otherwise still intact (meaning not yet falling apart, as in the feature photo above). In contrast, the south shore of Bowen Island, which had a huge overpopulation of sunflower stars, is recovered, with no sunflower sea stars and no necrotic debris remaining in evidence.
Where the population density had been highest in summer of 2012, on the western shore of Hutt Island, all the sunflower sea stars are gone from that area, with rivers of ossicles (a hard body part) filling ledges and crevices (see video below).
The entire diving community should be engaged to monitor the spread of this wasting syndrome, which may be limited to adjacent areas with extreme overpopulation, or it could continue to spread into areas with more typical abundance levels. That remains to be seen, and the Aquarium’s Howe Sound dive team will continue to monitor locations where baseline data are available. Whether this syndrome spreads up the Sunshine Coast or across to Vancouver Island or south into Puget Sound remains to be seen. Reports can be sent to email@example.com .
Blog post written by Dr. Jeff Marliave, Vancouver Aquarium’s vice president of marine science.
With the support of Sitka Foundation, the Vancouver Aquarium is embarking on a two-year project to train divers to identify marine life in Howe Sound, as part of our commitment to the research and conservation of this area. The information they glean on Howe Sound’s sea life will be presented in this series of blogs, and will be used to educate students taking part in the Aquarium’s school programs and AquaVan visits to inspire the next generation to keep learning more about marine biodiversity in British Columbia.
SOURCE: Vancouver Aquarium
Photo Credit: Neil McDaniel