About This Project

In Monterey, CA, two of the dominant kelp forest-forming species are giant kelp and bull kelp. From 2014 to 2016, the largest marine heatwave in recorded history developed off the coast of CA, raising temperatures 2-5°C above average sea surface temperatures. This led to the complete replacement of acres of kelp forests with urchin barrens. We seek to explore how urchin food choices and the management of urchin barrens impact the re-establishment and abundance of giant kelp and bull kelp.

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What is the context of this research?

Currently, in Monterey Bay, there are extensive acres of urchin barrens – areas where there are so many urchins that they completely eat all the available kelp. In Spring 2021, urchin fishing restrictions at Monterey Bay’s Tanker Reef will be removed to allow the organized removals of urchins on a large scale. This urchin removal effort provides a unique opportunity in central California to assess urchin impacts on kelp recovery. In order to fully understand how to best restore kelp forests, it is important to understand urchin food preferences for kelps. Bull kelp and giant kelp are both known to be great food sources for urchins, but no studies have investigated urchin preferences between these two species when they grow together or how they impact the survival of young kelps.

What is the significance of this project?

Bull kelp and giant kelp often occupy two different habitats: bull kelp in the north (colder water and larger waves), and giant kelp in the south (warmer water and calmer conditions). In Monterey, these two species are often seen growing close together. While urchins prefer bull kelp and giant kelp over other seaweed species, our study seeks to determine if one of these kelps is more preferable than the other. Answering this question can help us understand whether one of these species is more likely to survive in urchin barrens and establish a kelp canopy faster than the other. As urchin densities are being managed to promote kelp reforestation, my research will provide managers information about the expected results for kelp growth and reforestation.

What are the goals of the project?

I will conduct an experiment on food choice and availability to understand how urchin choices between kelp species may impact kelp vulnerability to urchin grazing. In the lab, I will set up large tanks with different proportions of each kelp to measure how much the urchins eat and whether they eat one kelp more than the other.

After I learn about urchin food choices in the lab, I will outplant kelp in Monterey Bay to compare the effects of urchin grazing and competition among juvenile stages of kelps in sites with both managed and unmanaged urchin populations. I will choose 3 sites in Monterey (one with urchin removal and two without) to plant baby kelp and will come back each month to measure kelp growth and count how many kelps are still surviving.