Sea stars along B.C.’s coast are showing signs of recovery after a decade of significant decline from sea star wasting disease. Scientists have made a major breakthrough in understanding the disease, offering hope for the restoration of these vital marine predators and their ecosystems.

Growing up in Ontario, the ocean felt kind of distant. But even after nearly five years of living on the West Coast, I still find myself in awe of the landscape and the wildlife around me. On my daily walks along the Vancouver seawall, I often spot harbour seals popping their heads above the surface, curious and unbothered – I like to call them the “puppies of the sea.” And on rare, lucky days, I’ve even caught sight of sea otters rolling and cuddling in the water. Of course I love watching these more familiar coastal creatures, but there’s one aquatic species in particular that continues to capture my curiosity the more I’ve learned about it — the sea star.

Sea stars (commonly called starfish) are fascinating. Just recently, I learned that they can have anywhere from five to twenty-four arms, and that they actually have two stomachs – one of which they can push outside their body to digest food externally. The most common sea star of the Pacific Northwest to find near Vancouver is the pisaster ochraceus, also known as the purple sea star (though they are often orange too), ochre sea star, or ochre starfish. Ochre sea stars are an important indicator for the health of the intertidal zone of the Pacific Ocean, and are considered a keystone species – species that are critical to the survival of the other species in the system. 

WHAT’S HAPPENING TO SEA STARS?

Since 2013, the  mysterious sea star wasting disease has wiped out roughly 90% of sea stars along North America’s West Coast, from Alaska to Mexico. The epidemic has devastated more than 20 species, hitting the sunflower sea star (the largest sea star in the global ocean) especially hard. Once abundant in B.C. waters, the sunflower sea star is now on the International Union for Conservation of Nature’s Red List of critically endangered species.

The loss of sea stars has had a profound ripple effect. Sunflower sea stars are natural predators of sea urchins – and without them, urchin populations have increased exponentially. Those urchins, in turn, have devoured the kelp forests that once blanketed the coastal Pacific waters. In some areas, up to 95% of kelp forests have vanished. These underwater forests are biodiversity hotspots – they’re the rainforests of the ocean – home to fish, sea otters, seals, and countless smaller organisms, and they are in peril as a result of the loss of sea stars. 

A BREAKTHROUGH IN A DECADE-LONG MYSTERY

For over a decade, scientists struggled to understand what was causing the disappearance of sea stars. However in August of this year, they believed to have found the culprit: a strain of a bacteria or pathogen known as Vibrio pectenicida. The discovery, published in Nature Ecology and Evolution, seemingly solves the mystery that reshaped our coastal ecosystems, and represents a major step towards addressing the outbreak and recovering the sea star population.

A PACIFIC CONVERSATION COMEBACK STORY

Amid the loss, researchers have also recently found healthy adult colonies of sunflower sea stars in B.C.’s central coast fjords. These findings don’t necessarily mean that sea star wasting disease hasn’t reached the fjords – it has – but compared with offshore islands, the sunflower sea stars population there is larger and more abundant, suggesting that the fjords may have served as a refuge. Protecting these populations could be crucial for the species’ recovery, and serves as a reminder that nature, when given the chance, can heal! 

Scientists are continuing to explore how to support sea star recovery and restore the kelp forests. This could be the making of one of the Pacific’s greatest conservation comeback stories. When I moved from Toronto to Vancouver, I expected to be amazed by the mountains, the ocean, and the rich, dark greenery. What I didn’t expect was how often I’d get to see aquatic life just steps from my apartment. Yet, I continue to be amazed at how alive the coastline is, especially when I can see the dazzling oranges and purples of our sea stars in the water clinging to the rocks at low tide, just steps from the shore line. 

Sea stars are a symbol of local biodiversity and living proof of how interconnected Canada’s coastal ecosystems are with the rest of the world. So how can we help them? Simply taking the time to learn about these creatures is a great start – it helps us appreciate the life thriving right in our own waters. From here, we can turn our attention to conservation groups and efforts, whether that is occurring at the green space in our local communities or just beneath the surface of our shores. 

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