July 8, 2021

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By Madison Churchill, PNW Protectors


Dense kelp forests once created a thick border up the coast from Baja California to Alaska. These underwater forests rival Amazonian rainforests for productivity and biodiversity. Heaping matts of kelp can be seen pooled up on the surface; a glimpse into a complex structure underneath. Stretching hundreds of feet tall in some places, these towering stalks are great connectors between the waves and the seafloor. Most people only see kelp on the surface, where it drifts along in thick rust-brown tangles. It’s quite a sight to behold even from above, but this is as far as many people go. At PNW Protectors, we wanted to dive deeper and explore the ecosystem from a different angle. Freediving through these ancient forests has given us a unique perspective and has allowed us to document changes that most people never witness. 

 

(c) Hannah Gabrielson

 

Spring is a very special time for freediving in Washington State. This is when our native kelp forests begin to grow back after being gone all winter. Tiny bulbs from juvenile bull kelp can be seen sprouting up as little underwater nurseries form. They start out small enough to fit in the palm of your hand but can grow taller than a house. Weaving through the underwater landscape, we see hundreds of little kelp sprigs popping up all around. They begin to rise in thick clusters, but most of them won’t survive. In recent years, the miraculous regrowth of kelp has been scarred by plagues of sea urchins. Their natural predators have been wiped out, and there’s nothing to keep them from decimating entire kelp forests. PNW Protectors has been working with local scientists to figure out the best way to restore our underwater forests. This action plan includes the re-introduction of Sunflower Sea Stars, a very effective predator against urchins.  

Seven years of freediving through Salish Sea kelp forests have allowed PNW co-founders Snow and Cy to observe changes to this ecosystem throughout the years. In just a few years, they have witnessed this incredible underwater forest dwindling away. Each year, less and less kelp lives through the season. Kelp forests are incredibly resilient and complex ecosystems that have survived through biological changes for millennia, but a recent shift in the balance has put this vital habitat at risk. Local scientists and observers are working together to restore kelp forests and slow the degradation. We look to an unexpected hero to help save our kelp forests: The Sunflower Sea Star. These twenty-four-armed echinoderms can cruise through the sea floor at top speeds eating sea urchins, keeping these destructive little invertebrates at bay.

Disappearing Forests

Importance of Kelp

Kelp forests provide a multitude of benefits to marine life. They create biodiversity hotspots, which serve as little pockets of life, dotted along the coast. This biodiversity comes in the form of many different species interacting together in an interwoven web, each with its own role to fill. The diverse structure of kelp creates opportunities for many types of marine life to thrive.

 

(c) Hannah Gabrielson

 

Photo Credit: Hannah Gabrielson

Kelp affixes itself to rock or other substrate with a root-like system called a holdfast. The tall stalk is called a stipe, which can grow multiple feet in a day. A gas-filled bulb at the top gives the kelp buoyancy so that its long golden streaming blades can lay on the surface. Although it has a very plant-like structure, kelp is actually macro-algae, and not a plant at all. This varying structure creates unique niches for different marine life to seek shelter, food, and opportunity.

These underwater forests are home to a lot of invertebrates like crabs, nudibranchs, anemones, urchins, and sea stars. They spend their lives sprinkled across the rocky seafloor, living amongst the holdfasts. Kelp crabs and other invertebrates can be found clutching blades of the kelp, swaying with the currents. Fish can also be found in the protection of kelp forests. Glimmering shoals of herring move fluidly throughout the aquamarine water. Burnt-orange rockfish can be found meandering around kelp forests for decades. Sculpins and other small fish also live nestled around the rocky seafloor.

 

(c) Hannah Gabrielson

 

This incredible trophic base and abundance of prey bring larger predators. Octopus, birds, seals, sea lions, and even orcas, reap benefits from the biodiversity that kelp forests attract. Everything is interconnected here. In a world where we are rapidly losing biodiversity, these hotspots are key in providing sacred habitats and safe spaces for marine life.

Kelp forests also provide numerous benefits to humans. Indigenous communities have created strong relationships with the kelp, and continue to do so today. Traditionally, these biodiverse habitats have helped to sustain humans, from eating kelp itself to using it in fishing practices, to using it in ceremony, or otherwise benefitting from the many animals it attracts.

It’s thought that kelp forests are even more productive at producing oxygen and sequestering carbon than rainforests on land. Much of the air we breathe in the Pacific Northwest comes from the sea. Rich, healthy, productive ecosystems benefit all of us every single day. Their ability to take carbon out of the atmosphere makes kelp a powerful ally in the fight against climate change.

Threats

Like most other natural spaces, kelp forests are impacted by human activity. The combination of overfishing and over-polluting results in a loss of biodiversity that ultimately impacts the entire ecosystem. Currently, a combination of factors has resulted in a bloom of sea urchins, and they’re throwing off the balance.

Having a few urchins can be helpful to the ecosystem because these kelp-eaters can help to clean up dead or diseased bits of algae. These little vacuums make their way across the seafloor, cleaning up the dead bits. Urchins can benefit kelp forests in small numbers because they become prey for larger species such as otters, eels, and sunflower sea stars.

 

(c) Hannah Gabrielson

 

However, when these larger species are eliminated, the urchins have no natural predators. These efficient little grazers begin to overpopulate and decimate the kelp forests along the West Coast of America. These purple or green-spiked invertebrates hustle around on tiny tube feet, gnawing down kelp holdfasts, detaching them from the seafloor and setting them adrift. Sometimes they devour it entirely.  

Throughout the years of freediving the same spots around San Juan Island, the PNW Protectors team has witnessed this urchin-induced destruction. Every year, more urchins have popped up, and it’s becoming harder and harder for young kelp to establish itself. We are missing some of our predatory keystone species, and the result is widespread urchin barrens.  

Diving at one of our main sites on the west side of the island, there are spots where you can’t even see the bottom because there are so many urchins side-to-side. They are already creating dead zones. PNW Protectors has been documenting the changes to the ecosystem, and we have witnessed the rapid degradation of kelp forests first-hand.

Sunflower Stars & Interconnectivity

Role in the Ecosystem

The Pacific Northwest is home to one of the largest sea star species in the world: The Sunflower Sea Star. An incredibly cool, alien-like species that roam the seafloor, these echinoderms are quite unlike anything else. Stretching up to a meter across, and with up to 24 arms all the way around their bodies, they are truly unique. With size, comes speed. They are one of the fastest invertebrates, shuffling around on tens of thousands of tiny tube feet on their underside.

Sunflower stars are one of the most effective predators for keeping urchins in balance, often feeding on the young urchins which help to keep the population in check. They regulate the species and help to prevent urchin barrens, making them a very important species for kelp forest health. These colossal sea stars can be purple, gold, yellow, and sometimes even red. Old photographs show piles of sunflower stars all laying on one another in heaps, but now it’s a rare sight to see one.

Sea Star Wasting

Tidepooling or diving along the coast is a great opportunity to witness sea stars in the wild. However, many that we encounter appear to be sick. A slight curling of the arms signifies an early stage of Sea Star Wasting (SSW,) a condition we still don’t fully understand. Within a few days the curling will give way to a more severe symptom where the limbs of the star appear to be melting. This condition has a high mortality rate, and it acts quickly. Within only a few days, this can kill the star.  

Sea Star Wasting is a condition we’ve known about for less than ten years. Initially, scientists thought it was a disease, but that theory was retracted and now even the nature of the condition is unknown. It’s likely a byproduct of climate change in one way or another, but we don’t quite know where it comes from or how it spreads. We may not fully understand the specifics, but we know how destructive SSW can be. In just a few years, SSW has wiped out most of the sea stars along the Western coast of the United States and continues to affect echinoderms around the world. This decline in population has left urchins unchecked to feast voraciously on the kelp.   

 

(c) Hannah Gabrielson

 

Collaborative Solutions

PNW Protectors has partnered with Friday Harbor Lab to aid in their research on Sunflower Stars. We believe this to be one of the most important keystone species for defending kelp, and has become a big focus in kelp restoration. At the lab, scientists are rearing baby Sunflower Stars in tanks, as well as studying adult stars. Our underwater observations help to complete the full puzzle of this species.

By working together from multiple different angles, the Pacific Northwest scientific community is slowly piecing together our understanding of SSW, and how we can prevent it. Any diver or tidepooler in the Pacific Northwest can help this study by submitting their sea star photos here. This data helps researchers understand where the remaining sea stars are located, and the environmental conditions they survive in. This citizen science element is crucial, as scientists are often unable to monitor the underwater world consistently. Working together, we can start to fill in the gaps. Together we can save this precious ecosystem.

 

(c) Hannah Gabrielson

 

The rearing of juveniles in the lab can help to create the next generation of healthy Sunflower stars, and piece together the mystery of their disappearance. The goal one day is to have a resilient sea star population that can sustain itself naturally, and keep the urchins at bay. PNW Protectors has been helping to document this journey through film and photography and will continue to do so with the help of our research freedive team. Follow along with us as we work towards revitalizing our underwater forests and healing the Salish Sea ecosystem. We are the eyes beneath the sea, and the voices above it.

PNW Protectors is a 501c3 non-profit organization dedicated to protecting the Salish Sea and the Southern Resident Orcas through education, public awareness, freediving, art, and empowering daily actions for everyone worldwide.

Visit PNWProtectors to learn more about our mission and current projects.

 

(c) Hannah Gabrielson

 

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