Volunteer Divers Hope to Restore Kelp from the Ground Up

Can people pick enough urchins to save North Coast kelp?

January 7, 2021
bubbles and kelp canopy
A diver’s bubbles rise toward the sunlit surface and kelp forest canopy. (Photo by Tristin McHugh)

I dove into a kelp forest for the first time in Monterey nearly a decade ago, and it was unlike anything I had ever experienced before. Towering flexible “trees” stretching to the surface, held vertically only by properties of gas laws. What is this place? Then came the forest creatures. Who are you? I wanted to get to know them. That moment underwater affected me so vividly and profoundly that, from then on, I have lived in a new reality: a confluence of life on land and in the sea. My daily routines are dictated by the swells, winds and tides, and my eyes are always on the water. It’s a complicated love story and many of my friends, peers, and colleagues, can relate: when it’s good, you go.

Now I’m seasonally amphibious, spending the winters on land, and summers in the sea. This is what brought me to Reef Check and the coast of Northern California. 

Reef Check is a nonprofit dedicated to monitoring reefs all over the world, and training recreational scuba divers, as citizen scientists, to survey their local reefs. We focus on encouraging local action through education and experience while collecting long-term ecosystem health information. Since the first Reef Check coral reef survey in 1997, our volunteer EcoDivers have completed over 14,000 surveys in 102 countries and territories worldwide. Our initiative is built on over 20 years of global reef health data. In California, our program was founded in 2005; and since then, we have established over 120 sites that we monitor annually, collecting information on fish, algae, invertebrates and habitat. We ultimately document and track reef health over time, while facilitating community involvement in data collection. 

The ocean has a chronic fever, and the question is what we can do about it.

Around the world we face localized reef health risks such as dynamite fishing, dredging, pollution, ghost nets, and poaching. But the major threat affecting reef health globally is not simply a singular visible, tangible action, but instead, an invisible one: warming oceans. 

It can be hard to imagine the ocean absorbs any heat when you dip a toe into the chilly waters of the Northern California coast. But, on Earth, our ocean acts as a “sink” and absorbs most of the excess heat from greenhouse gas emissions made on land. A 2013 report by the Intergovernmental Panel on Climate Change (IPCC) reported that since 1970, more than 93 percent of excess heat from greenhouse gases had been absorbed by the ocean. This transfer of heat results in elevated ocean temperatures, and warming oceans. Although a change of 1-4 °C might not seem like a huge jump in temperature to us on land, fractions of degrees can drastically alter water density properties and life-history characteristics for many organisms in the ocean. Many organisms use temperature cues to begin particular chapters of their life like, breeding, feeding and migrating. If conditions are not ideal, the organism may forgo these events. Think about if your internal body temperature was consistently elevated by 1-4 °C, resulting in feverish conditions, for years on end. How would your body feel and react? The ocean has a chronic fever, and the question is what we can do about it.

kelp canopy
The bull kelp forest canopy, viewed from below. (Photo by Tristin McHugh)

Many of our Reef Check chapters and partners in the tropics have transitioned from monitoring reefs to rebuilding lost reef habitat after coral bleaching and other destructive events have disturbed a particular place or region. Our California Chapter has taken inspiration from their (and many other phenomenal organizations) work and started to address similar challenges in our temperate water: using collaborative restoration practices to help regrow kelp forests that have experienced catastrophic deforestation. 

On a rocky reef (reefs made of rock, as opposed to coral), kelp and other sessile (sedentary) organisms adhere to the benthos (bottom) and create three-dimensional structure to the underwater landscape. That structure creates the magical, towering underwater forest seascape that drew myself and so many others to scuba diving. Marine alga is one of the organisms that competes for space, light and nutrients on the reef, much as a land plant would on a more familiar forest floor. “Deforestation” calls to mind images of forests being burned to the ground to make room for cattle, chainsaws cutting through old growth-forests, and animals being displaced along the way. We’ve been watching it happen on land in real time for centuries. Thinking locally, the recent wildfires of California may come to mind as a prime example of terrestrial deforestation. However, deforestation happens underwater too, in temperate rocky reefs all over the world where marine algae exists (New Zealand, Norway, Alaska, Japan and many more). California is no exception. 

Since 2014, canopy-forming bull kelp in northern California, primarily along the Sonoma and Mendocino county coastline, has declined more than 90 percent due to a combination of extreme warm water events (the Warm Blob and El Niño) and ecological stressors, like increases in native purple sea urchin populations, which feed upon the kelp. Prior to the fur trade, sea otters occupied the entire eastern Pacific and helped keep urchin populations in check; since 1840, sea otters have been functionally absent from waters north of the Golden Gate. In addition, predatory sea stars in the Eastern Pacific succumbed in 2014 to a mysterious marine disease known as the Sea Star Wasting Syndrome. This extreme event significantly reduced sea star populations, enough so that top predators like the sunflower star became locally extinct in Northern California waters. Our Reef Check team has not seen a sunflower star since the catastrophic die-off. The ecosystem structure and function was dismantled, and unfavorable oceanographic conditions pushed the kelp forest into an alternative state of existence. Poor oceanographic conditions, the loss of apex predators (otters and sea stars), and a purple urchin recruitment pulse and subsequent grazing led to a large-scale shift from bull kelp forests to urchin barrens across most of Northern California. This combination of stressors, each facilitating and exacerbating the other, led to considerable aquatic deforestation. 

urchin barren
A Northern California urchin barren. (Photo by Tristin McHugh)

 This shift has caused significant losses of kelp forest biodiversity and ecosystem services such as structural habitat, nutrient transport, and localized chemical buffering. From a fisheries perspective, the loss of the kelp forest resulted in the collapse of the North Coast commercial red urchin fishery starting in 2015 and the closure of the recreational red abalone fishery in 2018. These closures have caused economic devastation in the rural coastal communities of Northern California. Further, the abrupt deforestation was shocking and heartbreaking to the inhabitants of the North Coast, who recognized kelp forests for their intrinsic and cultural value. Warming oceans were not happening in a few decades or “in another lifetime”, they were here, now. With the surmounting evidence supporting the importance of forests above and below the waterline, large-scale deforestation poses a severe and imminent threat to global health. And although there is a sense of sadness and despair to the stories of ecosystems in peril globally, there is also a momentum of hope and energy from those willing and eager to confront it. What if there was something that we could do, right here and now, to approach this issue through enhancing our understanding of underwater deforestation? 

In February 2020, California’s Ocean Protection Council (OPC) granted Reef Check funds to design and implement a Northern California Kelp Forest Restoration project, with the goal of facilitating a shift from urchin barren to kelp forest on targeted reefs, and of understanding the costs and logistics associated. Our effort is part of the state’s larger initiative to support kelp research and restoration efforts, to obtain a better understanding of the drivers of the kelp crisis and potential mitigation approaches, and to “improve the state’s scientific understanding of restoration techniques that may provide relief to coastal ecosystems and economies recently devastated by climate-driven kelp collapse,” say two of my close collaborators, James Ray from the California Department of Fish and Wildlife (CDFW) and Mike Esgro, a member of the OPC staff.

In addition, Reef Check will assess whether the grazers (urchin) can be reduced below the theoretical threshold of less than two urchin per square meter, which, from other restoration efforts happening globally, is understood to potentially reduce herbivory enough to allow kelp recovery. We will also be assessing if urchin densities maintained over time to allow kelp to grow and serve as a kelp oasis, providing spores (kelp seeds) to surrounding areas. In close collaboration with OPC and California CDFW, we have designed a controlled approach to understand the effectiveness of the strategy and costs associated. With objectives and goals in mind, it was time to begin.

urchin and kelp
A purple urchin and kelp on the seafloor. (Photo by Tristin McHugh)

In compliance with Mendocino County’s shelter-in-place orders, the first thing my partner and I did was a motorcycle drive-by of our Reef Check sites. We had not seen some of these sites since State Park beaches had closed, and I was beyond curious to see how they looked from the surface. As we circled the bend at Caspar Cove, we couldn’t believe what we were seeing. It was a magnificent sight: kelp growth in the middle of the cove! This splendid surprise gave hope that, if good ocean conditions held, this would be a good year to expand the naturally occurring kelp patches.  

When we started diving in June 2020, the water was a chilly 7.2-8.9°C (45-48°F) which is prime for kelp growth. These good conditions held for the summer. As we collected ecosystem information (such as fish, invertebrate and algae densities) from a suite of our long-term sites, we continued to see kelp making its way to the surface unlike what we had seen in previous years. This was the first year in many that we were seeing kelp canopy cover increase versus decrease. Upon diving these sites, we found that purple urchin were still occupying space on the rocky reefs, but interestingly, that kelp was popping up in areas adjacent to the rocky reefs in sandy/cobble habitats that are less desirable to urchins. Considering the annual life cycles of bull kelp, wave exposed and/or “poorly attached” (to cobble, sand) individuals are likely to be removed. While kelp’s presence was promising, its attachment to hard reef would be critical for creating bull kelp refugia that would also support growth of perennial stipitate and coralline algae, the latter of which acts as a juvenile abalone magnet. From a kelp restoration prospective, this created the ideal scenario for us to reduce herbivore pressure on our targeted restoration reef and leverage the good ocean conditions and kelp spore availability. The goal was to create space for a diverse assemblage of spores, and “blend” the kelp into our restoration area.

urchin diver removes urchins
A commercial urchin diver removes purple urchins as part of a kelp forest restoration project near Fort Bragg. (Photo by Tristin McHugh)

Following our pre-restoration surveys, we launched the Kelp Forest Restoration project in August 2020, and 13 highly-skilled and experienced commercial urchin divers began to remove purple urchins from the first restoration area in North Noyo Cove, Fort Bragg. We chose North Noyo as a site to begin restoration for three main reasons: 1) It is close to the harbor and relatively protected from adverse ocean conditions, maximizing our number of work days; 2) it is home to a small extant kelp patch by the river output north of the jetty that survived the marine heat waves of 2014-2019, providing us with some promise of spore availability close to the restoration area; 3) following diver reconnaissance surveys, there were identifiable “choke points” which could theoretically minimize urchin encroachment into the restoration area. 

The months of August and early September yielded wonderful ocean conditions, allowing the research and commercial divers to frequently access and service the restoration area. We are now two months into the kelp restoration project at Noyo Harbor, and commercial divers have successfully removed over 21,000 pounds of purple urchin across just over six acres of the site. Following the removal of the urchins, Reef Check divers conduct routine quality control surveys (counting urchins, kelp and video documentation) to assess the effectiveness of the removal effort and to compare reefs before and after restoration activities with “control” reefs that will not be restored. Following removal from the restoration site, urchins are taken back to Noyo Harbor where Reef Check staff and volunteers further process the urchins and measure a number metrics, such as body weight and size, stomach contents, and bycatch. These metrics provide information to better understand how well various urchin removal methods work, and to investigate the biology of the urchins occupying the reef. To complete the loop, processed urchins are currently being utilized as compost and as a soil additive derived from their calcium carbonate “shells.”

We are now two months into the kelp restoration project at Noyo Harbor, and commercial divers have successfully removed over 21,000 pounds of purple urchin across just over six acres of the site.

Diving in the restoration site prior to the urchin removal efforts, and now, these two time points of the same reef are like night and day. Observing this marked transition has sparked a whole new curiosity about our role in the system, and what these devastated reefs could look like when a systematic approach to culling urchin is taken. Visually (and quantitatively) observing the transition from thick piles of purple urchin, to now having to look for them through the remaining red urchin was something we anticipated, yet it’s impressive nonetheless. Still, we have a lot of questions. What will it take for us to keep this area cleared of purple urchin? Will our post-restoration fall surveys yield a success in reducing urchin densities to the targeted theoretical threshold? Are red urchin posing a threat to the growth of kelp? Will the site hold through the winter? Will ocean conditions be favorable next year? And will our promising efforts yield the return of the kelp forest our coast so desperately needs?

Although the start of this project is revealing favorable outcomes after a few months, we are far from understanding the true implications of our intervention, and the outcomes. Existing funds support the continuation of these restoration efforts through at least May 2021. Efficacy and outcomes of these urchin removals will play a vital role in determining how resource managers choose to move forward with kelp restoration strategies statewide, thus helping to evaluate the costs and benefits of human intervention in a dynamic oceanic environment. By maintaining communication and collaboration with CDFW and OPC, our findings will support the state of California in understanding one of the biggest and most pressing challenges facing our coast and ocean. Further it will inform kelp restoration strategies globally, to other communities facing similar issues with kelp loss.

diver's compass
Descending toward the rocky seafloor. (Photo by Tristin McHugh)

It is not unreasonable to feel the emotional toll of a rapidly changing globe in this Anthropocene epoch. It’s inextricably linked to every other challenge facing our society. However, we can see this as an opportunity to critically think about and assess how our actions influence our role on earth. Acknowledging the emotions we feel over losing wild places that we love is crucial to addressing the challenges facing it.  To think we are on the periphery of the ecosystem is apocryphal, as we are involved just as the birds, kelp, and fish. It is our responsibility to nurture these natural places for future generations to enjoy, even if we must put in the work to rebuild it ourselves. It will never be what it once was, yet we are on the precipice of a renewed relationship with our natural resources.

Observing the towering flexible “trees” this season in the North Coast, I was brought back to my first experience in Monterey: an observer in an underwater forest teeming with life that I still yearn to understand. If anything, I have more questions now than ever before.  As marine life adjusts to the space we have created for them on the reef, and microscopic algae emerges from the rock to which its parent’s spores landed, I ask myself again, “who are you?”

About the Author

Tristin McHugh is a subtidal ecologist and kelp forest restoration practitioner based in Mendocino, California. She received her B.S. from the University of California Santa Cruz where she majored in Marine Biology and minored in Legal Studies and received her M.S. degree in Biology with an emphasis in Ecology from San Diego State University. Her current interests include kelp forest ecosystem dynamics and specifically the causes and impacts of phase shifts from kelp forest to urchin barren. When she is not in the water, you can find Tristin combing the beaches of the North Coast with her partner and pup, Ed Ricketts.