Purple Sea Urchins: California’s oceans doom
The Pacific purple sea urchin scientifically known as Strongylocentrotus Purpuratus is a species of sea urchin that is native to the Pacific east coast. They are fairly small, approximately 4 inches, but can live up anywhere up to twenty to seventy years. Their diet mainly consists of kelp and their predators are mostly starfish, otters and humans. The purple sea urchin was always an important creature in the ocean’s ecosystem, but after the 2011 HAB event, the purple sea urchin has had a severe impact that has mostly hurt the environment surrounding it.
Characteristics and Roles
The purple sea urchin is one of two common urchin species found off of the coast of California. They are the smaller species only growing up to 4–5 inches while the red urchin can grow up to 7 inches in diameter with 3 inch spikes. Although they’re fairly small, they can live up to seventy years and reach sexual maturity at around 2–3 years producing around twenty million eggs a year of which on average, a fourth get fertilized. Their primary role in the ecosystem is to consume kelp in order to provide corals and other creatures space within the environment and nutrition. Their primary predators are humans, otters and starfish. Due to their rapid reproduction rates and low predation, they have been able to reach new population highs within the last couple of years.
Population Boom
The purple sea urchin population was always controlled by predators such as star fish and sea otters. The urchin population was stable until 2011 when the urchin, starfish and abalone population was greatly hurt during a HAB outbreak. In 2013, as all of the populations were starting to recover, the starfish population was damaged by a sea star wasting disease, greatly decreasing the amount of starfish on the coast of California. In addition, over the years, the sea otter population has drastically dropped due to pollution and other environmental factors. With the two primary predators populations dropping and plenty of kelp, the purple sea urchin population sky rocketed upwards to 10,000%. The purple sea urchin began to dominate the Pacific coast floor having severe effects on the environment surrounding them.
Effects on the environment
As the urchin population grew, they consumed more and more kelp hurting surrounding organisms. Animals such as the California red urchin, abalone, crabs and many other organisms that depend on kelp as a food source, were greatly hurt by the decreasing amounts of kelp. Some creatures such as smaller fish or prawns that use the kelp as shelter or protection were left without a home and are more susceptible to predators. In addition, as the kelp population decreases, the coastal regions are more prone to bio-erosion, completely changing the environment type. Not only does the purple urchin hurt surrounding species by eating all of the kelp, but it also hurts them by taking up abundant amounts of the sea floor. The urchins dominate the California coastal sea floor not allowing other organisms to reside in the region or hide from predators. This greatly hurts native species and pushes them out of the region ultimately endangering those species as a whole.
Population Control Efforts
Efforts to control the purple urchin populations have been made, however, with the population already skyrocketing out of control, these efforts were futile. Several different tactics to decrease the urchin population were made. Scientists attempted to restore predator populations by breeding sea stars and sea otters in order to introduce them back into the wild and consume the urchins, but the reintroductions were unsuccessful. In addition, groups of scientists and regular divers have attempted to remove the urchins by hand and manually manage the populations, but with the amount of urchins that are already scattered on the ocean floor, and the speed of their reproductive cycle, these groups have not been successful. Another attempt to manage the population has been to advertise purple sea urchins as a food source to humans. This tactic has also been unsuccessful due to each urchin producing a very small amount of uni(sea urchin roe). It is not profitable for people to collect purple sea urchins and extract the roe when there are other species of urchin such as the red urchin which has more roe per urchin.
Conclusion
Overall, as the purple urchin population grows, the surrounding environment is unable to adapt. The population growth is detrimental and organisms are either on their way to extinction or are being forced to relocate and change their ways of life. In order to preserve the environment and native species, it is necessary to do something and properly manage the purple urchin population. Although scientists have been attempting to implement programs to control the population, they have not been having much success and are still struggling to find a way to handle the urchins.
Sources Cited
Hakim, J. A., Schram, J. B., Galloway, A. W. E., Morrow, C. D., Crowley, M. R., Watts, S. A., & Bej, A. K. (2019, January 26). The purple sea urchin strongylocentrotus purpuratus demonstrates a compartmentalization of gut bacterial microbiota, predictive functional attributes, and taxonomic co-occurrence. Microorganisms. Retrieved May 29, 2022, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6406795/
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Monterey Bay Aquarium. (n.d.). Purple sea urchin. Montereybayaquarium.org. Retrieved May 29, 2022, from https://www.montereybayaquarium.org/animals/animals-a-to-z/purple-sea-urchin
Purple sea urchin. California Sea Grant. (n.d.). Retrieved May 29, 2022, from https://caseagrant.ucsd.edu/seafood-profiles/purple-sea-urchin
