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Using machine models called boosted regression trees, UC Santa Barbara scientists are helping preserve kelp forests, critical habitat for many marine species.
A catastrophic and unexpected heatwave hit the Pacific Ocean in 2013. Named “The Blob,” this heatwave drastically altered the ocean conditions for many ecosystems along the Pacific coastline, from California all the way into Mexico.
The Blob was “a perfect storm of negative impacts to kelp,” says Arieanna Balbar, a postdoctoral scholar at UC Santa Barbara’s Caselle Lab. The storm, she explains, triggered what’s known as a “trophic cascade,” or a domino effect in which there is an increase or decrease of a predator, eventually leading to changes in the populations of other species.
Sea urchins, those dark, spiny balls that look like underwater burrs, were the species that saw a dramatic increase in population, mainly due to a quick decline in the numbers of their natural predators, sunflower sea stars.
The decline of the sea stars was triggered by the heat wave, which had left them vulnerable to sea star wasting disease. With these predators nearly wiped out, sea urchin populations exploded, and the imbalance set off a series of events that rippled through the food web and eventually devastated the kelp along our coastline.
Now, scientists at UC Santa Barbara are working with special machine learning methods to better protect the health of the ocean’s forests and prevent this kind of thing from happening again.
“We are using a machine model called boosted regression trees to model the relationship between environmental drivers,” Balbar says. With the model, she explains, they are “simulating what the future is going to look like.”
BRTs closely resemble our world. They allow researchers to mirror our environment and adjust its many components, like the temperature of the water, the nutrient concentration, the depth of water, the oxygen levels, and the kelp supply across the coast of California.
When the models are built, they reflect the current conditions in the Pacific Ocean. Researchers change elements and observe how the model reacts, gaining insights about how seaweed forests will behave. This, in turn, provides scientists with a better understanding of where and when to implement kelp forest restoration efforts, Balbar says.
Why focus on kelp forests? Because, as Balbar notes, they keep ocean ecosystems alive.
In fact, the vast majority of ocean species rely on kelp forests to survive. They keep many kinds of ocean life fed, sheltered, and protected from other predators. What’s more, fish and other marine life often give birth to their babies in the dense forests, rather than out in the open, where their offspring could be swept away or eaten by predators. Kelp forests keep the lifecycle of the ocean ecosystem thriving and intact.
‘We are using a machine model called boosted regression trees to model the relationship between environmental drivers,' Arieanna Balbar says. With the model, she explains, they are ‘simulating what the future is going to look like.'
Kelp forests also reduce our carbon footprint. Seaweed collects lingering CO2, stores it within itself, and sinks to the depths of the ocean floor, reducing the amount of fossil fuels in the atmosphere.
Balbar explains that we lost more than 90% of seaweed forestation along California's North Coast after the 2013 heat wave. What’s more, because our climate continues to get warmer, the nutrient supply is plummeting and the weather is changing in ways that we haven't experienced so far. Through her work, she says, she aims to help return our rocky shoreline to the thriving and vital world it once was.
5 Key Takeaways
- The 2013 “Blob” heatwave triggered a “trophic cascade,” drastically altering Pacific Ocean ecosystems and leading to the devastation of kelp forests.
- Kelp forests are vital for keeping ocean ecosystems alive. They provide food, shelter, and nurseries for marine life
- Kelp forests also help reduce our carbon footprint by storing CO2.
- UC Santa Barbara scientists are using machine learning, specifically boosted regression trees (BRTs), to model the relationship between environmental factors and kelp forest health.
- BRTs help simulate the future of the ocean and provide insights for where and when to implement kelp forest restoration efforts.
What You Can Do
Anything you do to reduce your carbon footprint — eat less meat, choose more sustainable transit like bikes or EVs, aim for energy efficiency in your home — helps kelp forests thrive. If you’re a scuba diver or free diver, avoid touching or crashing into kelp forests, and make sure to clean up after yourself and others — if you see plastic wrappers tangled in kelp, grab them and dispose of them properly onshore. You can also volunteer to help organizations like Reef Check conduct scientific surveys and monitor kelp forests along the West Coast.
