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Searching for sea stars in the midst of climate change

Starfish, urchin and a mudboot chiton in the tidepools off Laguna Point at Mackerricher Beach.
Starfish, urchin and a mudboot chiton in the tidepools off Laguna Point at Mackerricher Beach.

A team of scientists from the California Academy of Sciences converged on MacKerricher Beach on Sunday at dawn, as part of their yearly effort to document species along the California coast, using the iNaturalist app. This year, the search was on for sea stars, especially the pycnopodia sea star, which was the main predator of the purple urchin until most of the species succumbed to a wasting disease. Unchecked, the purple urchin have proliferated and eaten most of the bull kelp, a primary food source for other grazers. The abalone fishery has closed and the red urchin fishery is in bad shape. Aquarium biologists around the country, including Nebraska, are raising the pycnopodia sea star in captivity, trying to understand the animal before maybe, someday considering a reintroduction of the key predator.

Kylie Lev is a curator at the Steinhart Aquarium at the California Academy in San Francisco, which has several thousand larvae from a successful spawn with a pair of pycnopodia from San Diego’s Birch Aquarium. She took a break from documenting species at the end of Laguna Point to report that, “The spawn actually happened on Valentine’s Day, so all the stars could align.” Some of the larvae, which could eventually have up to two dozen arms, are currently sprouting their sixth limbs under her care.

Scientists are careful not to speculate on what caused the seastar wasting disease. But it did correlate with warming seas, around 2014. It’s part of a larger pattern that came home for Dr. Rebecca Johnson while she was observing tiny life forms at low tide. “I remember one day I was tidepooling,” she recalled. “It was still beautiful, and it was still super diverse. But I saw all these things, like hundreds of these little pink nudibranchs that normally you wouldn’t see. And barely any starfish, because they were recovering. And I had this realization, that that’s actually what climate change is. It’s just these shifts, and things looking a little different, and then the system behaving a little differently. It’s not like an apocalyptic wasteland. It’s just things changing.”

Anemone and purple urchin.
Anemone and purple urchin.

Johnson is co-director of the Center for Biodiversity and Community Sciences at the Academy of Sciences in San Francisco. Before joining about 20 of her colleagues in the tidepools at 6:30 on Sunday morning, she talked about Snapshot Cal Coast, a nine-year-old effort to survey the species along the coast every summer, when tides are at their lowest point. The work is supported by the California Ocean Protection Council. “We work together to make sure that the data that we’re taking are useful for them to help make decisions about coastal management,” Johnson said. Some of the observations that have been recorded during Snapshot Cal Coast events include species that have never been seen as far north as the United States, like a certain kind of sponge crab. Discoveries of invasive seaweeds have helped harbor managers get rid of the species before they took hold.

Dr. Nat Low is a data scientist with the Cal Academy. They’re using projections and a variety of information from previous Snapshot events as well as year-round iNaturalist observations to build an early warning and forecasting system to predict the effects of climate change. In the midst of all the efforts to restore the ecosystem so bull kelp can thrive again, Low expects another type of seaweed known as sea palm to decline. It’s due to a number of factors, but rising water temperature is the main driver of the expected event. “The sea palms are really special in that they like to grow in very wave-exposed areas,” Low said. “Basically, where the sea palms are, you probably don’t want to be standing when the tide comes in, because they take a big pounding.” Like all kinds of kelp, sea palm provides an important refuge for sea life. “So losing any kelp — and we’ve lost a lot of other kelp in the system, that takes away habitat, and then it makes it harder for other species to live,” Low concluded bluntly.

Sea palm on the far end of Laguna Point.
Sea palm on the far end of Laguna Point.

Dr. Elora Lopez-Nandam, who is designing the research on the pycnopodia at the Steinhart Aquarium, says it will be a while before anyone starts to think about releasing pycnopodia into the wild so they can eat their way back to a balanced ecosystem. “This is an ongoing conversation between California Department of Fish and Wildlife and NOAA, and multiple different aquariums and museums and research labs,” she qualified. “Our first initial proof of concept is, can we grow these in aquaria at scale, and show that we’re growing healthy happy animals. And then the next step will be to develop plans with governmental partners and people who actually live in coastal communities who will be affected by this to say, how do we design plans for reintroduction that really benefit everyone.”

There's plenty of work to do before the next round of studies, according to Lev, the curator raising the pycnopodia at Steinhart. The batch of dime-sized pycnopodia larvae busily growing more arms behind the scenes in San Francisco are full siblings that don’t represent a wide enough genetic range to offer a broad understanding of the species, which is what scientists need before they consider attempting to bring the sea star back to the wild. For example, there’s not much understanding of what caused the wasting disease in the first place, though Lev said there are “some potential treatments happening for animals that are experiencing wasting…Unfortunately, there’s not one characteristic that we can look for” that would signal whether an animal was infected or not.

Lev almost allowed herself to be optimistic about the potential for the animals to recover on their own in the colder, nutrient-rich waters of the upcoming La Nina; “But I don’t know that I have the evidence or the science to back that up,” she added quickly; “other than we did see a correlation between the warmer waters and the wasting events of past El Nino years. We do know that our oceans will continue to change, so we need to be thinking long term about how that change will impact the population…how it will impact the ecosystem around us.”

A young Giant Pacific Octopus.
A young Giant Pacific Octopus.

Local News
Sarah Reith came to Mendocino County in 2008 and worked as a reporter and freelancer, joining KZYX as a community news reporter in 2017. She became the KZYX News Director in March, 2023.