Linden Hunter-Pinsky
7th Grade, Gateway Middle School
Santa Cruz, CA
Investigating the Relationship of Sea Urchins (Echinoidea) to Giant Kelp (Macrocystis Pyrifera) Bed Recovery
Linden studied whether sea urchins (Echinoidea), which eat giant kelp (Macrocystis pyrifera), might prevent the recovery of this important ecosystem. He used a remotely operated vehicle to take videos of urchins on kelp beds, and showed sea urchin density was not related to kelp bed recovery.
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Project Background
Linden learned about how important kelp forests are, serving as habitat, protecting shores from erosion and absorbing carbon. “I found that California kelp declined because of a sea star wasting disease in 2013 and a heatwave in 2013-2016,” he says. While some kelp beds are starting to recover in Monterey Bay near where Linden lives, he also noticed more sea urchins (Echinoidea) in the tide pools, and knew that sea urchins grazed on giant kelp (Macrocystis pyrifera). He decided to find out if recovering kelp beds had fewer sea urchins.
Tactics and Results
Using satellite data from a site called Kelpwatch, Linden selected two declining, two recovering, and two stable giant kelp beds in Santa Cruz. Then, he borrowed a small Remotely Operated Vehicle (ROV), and used it to take videos of the beds. The hardest part, he says, was getting the ROV to the kelp. They can’t be accessed from shore, and are too close to use a motorboat, so Linden had to use a rowboat. “It wasn’t very stable and I got sea sick often,” he says. He carefully counted all the urchins in his videos, and calculated both the density of the sea urchins and the recovery of the kelp. He found that all of the kelp beds had relatively low numbers of sea urchins, so the urchins are probably not preventing recovery of the ecosystem. Instead, he says, other factors like runoff or sediment could be preventing kelp comeback.
Beyond the Project
Linden plays soccer and basketball and runs cross country, but soccer is his favorite. “I love that it isn’t just me out on the field: it is all my teammates who support me and have my back even if I have a hard game,” he says. He’s also gone to Invention Convention Nationals, a convention for student inventors. He’d like to be a mechanical engineer. “I love building different electric vehicles and models. I also love challenges and trying to figure out what is wrong or how to solve them,” he says.
