How hot is too hot? Bull kelp’s response to climate change

Presenter: Zachary Spade

Presenter Status: Graduate student

Academic Year: 22-23

Semester: Spring

Faculty Mentor: Mackenzie Zippay

Department: Biology

Funding Source/Sponsor: RSCAP

Other Funding Source/Program: CA Sea Grant

Abstract:
Between 2013 and 2016, Sonoma and Mendocino County’s coastal environment experienced a series of dramatic environmental changes: sea star wasting disease, a few marine heatwaves creating a stagnate, warm water “blob”, and a boom in purple sea urchin populations. As a direct result, these counties experienced a 90% loss in its bull kelp (Nereocystis leutkeana) coverage. While the loss of kelp can be mainly attributed to being consumed by the increased purple sea urchin population, the increase in sea temperature and formation of the “blob” has also affected the kelp. Using molecular approaches, we are investigating the thermal sensitivity of bull kelp across different life history stages and from multiple locations. This study is important because, like coral reefs in the tropics and giant kelp in southern California, bull kelp is a foundation species for coastal marine ecosystems here in northern California, providing food and shelter for a myriad of marine species, including many of importance to California’s economy. The results of our research could help us understand how or if different populations of bull kelp will be able to better tolerate future temperature changes.