What's Killing the Oregon Sea Star?
Many of the state's colorful tide-pool treasures are being destroyed by a mysterious wasting syndrome that could drastically change our coastal biodiversity.
It’s 5:30 a.m., and buoy horns cut ominously through the dense fog engulfing Depoe Bay. I’m trudging along the rolling intertidal pools at Fogarty Creek.
“Are you ready?” Bruce Menge, a professor of integrative biology at Oregon State University, asks me as he pulls waterproof boots and overalls over his jeans. The question sounds like a mere formality, but as I peer into the tide pools I’m not sure I am ready for what I see.
Back in the spring, he says, the tide pools were lined with thousands of healthy sea stars (commonly called starfish). Now, most of the sea stars are gone. The sickly few that remain hang limply from the bedrock, at risk of being crowded out by California mussels.
Since April 2013, a deadly—and unexplained—wasting syndrome has devastated the entire sea star population from British Columbia to Baja California and in turn imperiled the fragile tidal ecosystem. The disease reached Oregon in April 2014, affecting around 50 percent of Fogarty Creek’s sea star population. The total population has dwindled to a fifth of what it was. The symptoms are gruesome: Some develop lesions and become abnormally soft. They begin to disintegrate; their arms detach from their central disc and crawl away on their own. Tissue regeneration is nearly impossible. All of this occurs within two weeks.
Menge is one of four West Coast university principal investigators working with the Partnership for Interdisciplinary Studies of Coastal Oceans (PISCO), tracking and searching for implications of the die-off. Scientists still don’t know what causes this fatal unraveling, or how the disease spreads. But they do know that time is running short for some of the Pacific Coast’s most charismatic and ecologically important creatures.
The orange and purple Pisaster ochraceus, also known as ochre sea stars, feed primarily on mussels, which gives room for seaweed, algae, and sea anemones to grow. The OSU team has installed small metal cages in on open rock to help them understand what effect the complete absence of some species of sea stars would have on prey. One thing is certain: without the sea stars Oregon’s coastal biodiversity will change drastically.
Still, there is some hope that sea star larvae washed in from the ocean will develop into healthy juveniles. Later this day, Angela Johnson, an OSU faculty research assistant, will report that sites a few miles south of Fogarty Creek have only two of 15 healthy adults, but a majority of healthy juveniles and babies. “We are also finding smaller species of sea stars to be more resilient.”
“The scientist in me says the chances of recovery are low given what we have seen,” says Menge. “The optimist in me says that juvenile repopulation is possible.”
As we make our way back, the fog begins its sluggish ascent. For now, the future of sea stars is at the mercy of the ocean.