Kelp forests are an essential part of the underwater ecosystem; yet at present, the latest research has noted that their numbers have dwindled rapidly on the West Coast, especially in the Northwest region. This is because of an increase in sea urchins and a lack of sunflower sea stars - the name coined by scientists, as calling them “starfish” implies that they are fish, which they are not. A study conducted by The Royal Society found that increasing the sea star population would help to keep the sea urchin population down and restore kelp forests. This piece will break down the background and details of this issue, as well as what this will look like going forward.
Underwater kelp forests are the homes for hundreds of young species, including rockfish and herring, who get food and shelter there. Kelp has also been used to prevent ocean acidification, where the ocean absorbs high levels of carbon dioxide and the pH of the sea goes down. This can have harmful effects, such as decreasing a fish’s ability to detect predators and potentially changing the balance of predator and prey.
A count of these sea urchins solely off the coast of Oregon has found 350 million, meaning the sea urchin population has gone up by over 10,000% from 2014. The sunflower sea star - the primary predator of sea urchins - has been noticeably missing because of the rise in a disease called sea star wasting syndrome. This strange disease that has been around for nearly a decade causes sea stars to melt into goo. This poses a severe threat to the sunflower sea star population - which has decreased by over 90% - and with it, kelp forests. Further, sea stars have become necessary for keeping the sea urchin population down as another one of their main predators, sea otters, are being hunted and leaning towards endangerment.
Moreover, the cause of sea star wasting syndrome is fairly unknown, but scientists know that stress and parasites are factors. The disease enacts symptoms in various stages: first, the sea star appears flatter than usual. Subsequently, its arms curl over each other. Afterward, the sea star obtains white, oozing gashes; then its components detach themselves from the body. In the end, the sea star is nothing but some bones and flesh. The Washington Post describes it as something from a horror movie.
This brings scientists two problems, or rather, two options: decrease the number of sea urchins or increase the number of sea stars. There are teams following both paths.
The Oregon Kelp Alliance is dealing with purple sea urchins that blanket the ocean floor - this blanket is called an urchin barren. Once these urchin barrens are created, it becomes nearly impossible for the kelp in the area to grow back fully; even the slightest bit of kelp regrowth will be consumed by the urchins in a barren. The Alliance noted that just one of these urchins could have over 1 million babies yearly, so they are beginning a project to remove them from the ocean. After the urchins are removed, they are kept in a tank and fed seaweed until they are healthy and humans can eat their uni. This is called urchin ranching. A company called Urchinomics has already begun to create urchin ranches in Japan, Canada, and California. Another urchin diving business started in 1993, Oregon Sea Farms, is working on the same thing, fattening up sea urchins to sell for around $10 each, funded by the Oregon Wildlife Foundation.
Nonetheless, scientists estimate that it would take 15-20 years to remove the sea urchins just from Oregon, making this process an option but not an entire solution. They are still working to combat this, paying sea urchin divers to collect urchins that are damaged yet alive to be brought to an urchin ranch.
On the other hand, as keeping the sea urchin population down by human interference feels a bit unnatural to some, increasing the number of sea stars has been far more popular. One notable effort is by Tiffany Rudek, an aquarist at the Oregon Coast Aquarium who removes infected sunflower sea stars to help them recover. Rudek gives the sea stars a bath, killing the parasites that take advantage of its weakened flesh and disinfecting the animal with iodine. After doing that, she holds it against a wall to test the strength of its grip and pours a probiotic solution to restore its beneficial bacteria, just as humans do when they take probiotics. The process is meant to help with the sea star wasting syndrome and boost the star’s immune system. Another lab’s work is conducted by Jason Hodin, a marine biologist at the University of Washington, who is working with the Nature Conservancy to breed sunflower sea stars in captivity before releasing them into the wild.
One study found that sunflower sea stars will eat 0.68 sea urchins daily and even more if the urchins are starving. Research Associate at Oregon State, Sarah Gravem, said that might not seem like much, but it is estimated that there were once over 5 billion sunflower sea stars, which certainly adds up. These fierce predators have between 16 and 24 limbs, allowing them to grip prey easily and travel around 3.3 feet in a minute. This is highly beneficial for maintaining the sea urchin population reasonably, as many other predators, such as sea otters, are picky regarding which sea urchins to eat; the sunflower sea star will eat any sea urchins that come their way. Though the sunflower sea star is struggling right now, several individuals are working towards its recovery as they are not solely helping the kelp forests survive. All organisms on Earth are connected and will impact each other, which is why scientists and others must continue to fixate on this problem.
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