BC's sunflower sea stars are now endangered, but rays of hope remain

National Observer

a day ago

Sunflower sea stars clinging to life in BC's cold-water fjords are officially on the edge of extinction, a scientific advisory panel is warning.
A once-abundant predator of the sea floor along the Pacific coast, stretching from Alaska to Baja California, Pycnopodia helianthoides, has been assessed as endangered by the federal Committee on the Status of Endangered Wildlife in Canada (COSEWIC).
While disheartening, the decision isn't unexpected and could offer a margin of hope for the survival of the massive, vibrant sea star, said Alyssa Gehman, marine ecologist with the Hakai Institute.
The only type of its genus, an adult sunflower star Pycnopodia (which comes in a variety of purple, orange or pinks) is one of the largest, fastest sea stars in the ocean, often reaching a metre wide with 16 to 24 arms.
It has 15,000 tube feet that suspend it off the seafloor and allow it to move more than a metre per minute when on the prowl for prey, Gehman said.
'They kind of look like a hovercraft moving towards their food.'
The species has suffered catastrophic population declines of 80 to 90 per cent in the last decade due to a marine epidemic known as sea star wasting disease that causes white lesions on the many-armed creatures before rapidly reducing them to mush.
Sunflower sea stars clinging to life in BC's cold-water fjords are officially on the edge of extinction, a Canadian scientific advisory panel warns.
The wasting syndrome surfaced in 2013 along with spiking ocean temperatures caused by climate change, Gehman said. The disease attacks other types of sea stars as well, but it's decimated the sunflower variety, pushing them into virtual extinction in California and Mexican waters.
Pockets of sunflower sea stars have found some refuge from the disease tucked away in the deep, cold inlets of the BC central coast, Gehman said. However, those remaining populations aren't immune to outbreaks and their chances of survival remain fragile.
'While [being endangered] is clearly bad news, the silver lining is that COSEWIC's acknowledgment might finally generate momentum to save Pycnopodia — whether that's in the form of funding, policy changes, or conservation programs,' Gehman said.
The federal ministry of the environment and climate change will examine the committee's report in the fall to consider protecting the sunflower sea star under Canada's Species at Risk Act (SARA). It's illegal to kill, harm or capture wildlife listed under the act. Identifying critical habitat and devising a recovery strategy, complete with timelines and outcomes, is also required for a protected species.
'I hope it's a speedy process because there's real urgency,' Gehman said.
'From a conservation perspective, even though we have these really amazing refuge populations that give us a lot of hope, they're not stable … So, the more we can learn about what is happening with them, the more that can help us to try and conserve the species.'
The sunflower sea stars are carnivores that play an important role in ocean health, said Gehman. Their primary prey is sea urchins which, if left unchecked by predators, can mow down kelp forests that offer food and shelter for lots of different marine life.
Gehman and other researchers are monitoring between six and 12 fjords to pinpoint the conditions that offer sunflower sea stars the most protection against the disease.
Water chilled and churned up by Arctic winter winds channelled into the inlets seems to buffer the impacts, she said. In warmer weather, glacial melt creates a freshwater surface layer in the fjords. Since Pycnopodia don't like fresh water, the sea stars move deeper into saltier, colder water layers, which appears to slow but not completely prevent outbreaks, Gehman said.
Typically, sunflower stars in other areas of the coast prefer water temperatures around 16 C. But now it appears that water temperatures must be less than 12 C to limit the spread of the pathogen.
'The disease is actually changing what temperature would be best for them,' Gehman said.
The sea stars haven't adapted quickly enough to the disease to consistently avoid warmer waters, which makes understanding the factors at play in their cold-water hideouts critical for their survival, she said.
Research is taking place south of the border to breed sunflower sea stars that are more resistant to the wasting disease, so they can potentially be released into the wild to repopulate marine areas.
In future, Gehman wants to study other kinds of sea stars — like the purple or orange ochre sea stars on the West Coast— that have better withstood the withering disease in a bid for clues scientists could use to help out their much larger cousins.
Identifying and protecting coastal fjords that offer the best conditions for sunflower sea stars is also an important step.
Although the Pycnopodia situation is grave, Gehman says she recently experienced a rare and magical moment when the research team witnessed a massive spawning event involving 20 to 30 sea stars, while surveying one of the fjords.
'It's absolutely wild,' Gehman said,
The sunflower sea stars have pores that circle the centre of their body. The marine creatures stretch upward on extended arms and arch their bodies, with females releasing masses of pinkish eggs while males emit white clouds of sperm.
'Only the tips of their arms are on the bottom with their middle body tented up into the water column,' she said.
'There were some absolutely giant animals. It kind of looks like there's a halo of pores on them, and everything is pouring out into the water — it's really surreal.'
The spawning event is a hopeful sign these cold-water strongholds can offer the endangered species some measure of resiliency from climate change and disease, she said.
But the situation remains tenuous and variable, said Gehman, noting on the same trip researchers found sunflower sea stars had been wiped out in one inlet but had bounced back in another.
'So, scientifically, we're learning a lot while also being sad,' she said.