at 12:15 p.m. on tuesday, i was 50 feet underwater off the coast of northern california’s monterey bay. giant tree-like structures surrounded me, stretching up towards the sun. fish darted around the base of the stalks and among their leaf-like blades. crabs, urchins and bright orange starfish clung to the colorful, rocky seafloor. 

this underwater community is called a kelp forest, and it’s one of the dwindling few that still dot the shallow, cold waters off the coast of california. kelp, the cornerstone species of this ecosystem, reduces ocean acidification by storing carbon dioxide. its branches create one of the most biodiverse marine communities in the world.

in the past 10 years, kelp forests in northern california have seen a rapid shrinking. from just 2014 to 2015, the kelp forests declined 95 percent, according to nasa’s earth observatory. 

marine heat waves, weather events, and water pollution have played a role. 

but the main culprit? 

sea urchins. these spiky, fist-sized animals eat kelp and are responsible for decimating large swaths of the kelp forest, transforming them into rocky landscapes called urchin barrens. 

enemy #1

urchins are not an invasive species, however, and they have predators within the kelp forest community to control their population. so what has made their numbers skyrocket?

the ocean off the coast of california is usually quite cold for its latitude due to currents that bring water down from the north. but in 2014, a massive marine heatwave hit, lasting until 2016, according to noaa. “the blob” as scientists commonly refer to the heatwave, stressed the kelp, which thrives in cold, nutrient-rich waters. 

and just before that, in 2013, a peculiar disease called “sea star wasting disease” caused a massive die-off of the sunflower seastar, a key kelp forest community member that preys on urchins.

as the seastar population declined, the sea urchin population increased, eating the kelp at a rapid rate. urchins also can enter a state where they can survive starvation for long periods of time, according to a 2021 study published in the “journal of experimental marine biology and ecology”.  this means that once they have decimated a patch of kelp, they can stay alive without food until the kelp just barely begins to regrow, when they eat it again.

because of this process, giant kelp, which grows at the rapid rate of about a foot each day according to the monterey bay aquarium, can’t recover. 

fighting back

but the kelp forests aren’t without hope. scuba diving in monterey is still popular in what is left of the vibrant kelp forests, and as long as there are divers appreciating the beauty of the ecosystem, there will be people fighting for it. 

melanie moreno has been diving in monterey’s kelp forests since the great kelp die-off of 2014. she volunteers with reef check, a citizen science project that trains experienced divers on how to help save the kelp forests. usually, that entails smashing urchins. 

moreno said she remembers a time when everything was beautiful, when the preserves were lush and kelp canopies full. one famous preserve, lovers point, was once bursting with life and biodiversity according to moreno.

now, moreno says that the kelp in the preserve is almost completely gone, replaced by urchin barrens. 

i can attest to that. on a dive beneath the waves at lovers point two years ago, i found no kelp, and instead was stabbed by an urchin. 

but i know that lovers point was once a picture of beauty. my parents have been taking me scuba diving since i was old enough to get certified. while in graduate school, my mom taught newcomers how to scuba dive in monterey. 

she and my dad dove frequently, and one day, my father proposed to her underwater. they were in a lush kelp forest, at lovers point. 

a different world

as i descended below the kelp’s canopy and into what felt like a different world, i was greeted by bat stars, anemones, kelp crabs, an array of fish species, and colorful tiny sea slugs called nudibranchs. 

point lobos state park in carmel california is home to a few of the kelp forests that continue to thrive in northern california. here, i watched otters tangle themselves in kelp to prevent from floating away, great white egrets perch on the floating kelp canopy and humpback whales feed not far from shore.

visitors, with the proper permit, experience and gear can explore the kelp forests of point lobos in whalers cove and blue fin cove. 

the water was around 56 degrees fahrenheit as i reached the seafloor, chilly enough to warrant a thick, long sleeve wetsuit or a drysuit to stay warm. both of the two species of kelp, bull kelp and giant kelp, surrounded me. this is one of the few locations with the right temperature for both species of kelp to thrive, as bull kelp prefers the colder waters of up north and giant kelp thrives in the slightly warmer environment of further south.

but this “goldilocks” range might be shifting away from monterey due to climate change. 

“it’s causing the contraction or loss of kelp forests on their warm range limit,”  marine scientist kyle emery said. “at the same time it’s causing poleward expansion on the other side.”

emery researches kelp forests at university of california, santa barbara. he looks at the important role kelp plays in other ecosystems. the food web of beach ecosystems, for example, is sustained by kelp debris that naturally washes ashore. he also looks at the impact that climate change has on the kelp forest, and has hundreds of kelp forest dives logged. 

“there’s just so much to see and it’s so three dimensional that it really feels like you’re in a different world,” said emery.

the world inside a healthy kelp forest is not unlike that of the redwood forests on shore. 

“you’re swimming through kelp plants that are 40, 50 feet tall, just like you are in a forest of trees, and there’s just abundant, colorful life everywhere,” emery said. 

emery thinks that there is a wide array of things to love about kelp forests.

“people can see the visual beauty of a kelp forest, the abundance of life in a kelp forest, the potential use of products derived from kelp,” emery said, “once they find that connection, they, i think, resonate more with kelp forests in general and think about the protection and conservation.”