OCE-PRF: Do wildfires drive phytoplankton blooms in the California Current System?

University Of California-Santa Cruz, Santa Cruz CA

Investigators

Abstract

The frequency and spatial extent of wildfires along the US West Coast has substantially increased over the last fifty years. As a consequence of fire, large plumes of ash, black carbon, and other aerosols are injected into the atmosphere and transported away from burn areas where they often land on the surface of the ocean. Despite the geographical proximity to large fires, there is little understanding of how the deposition of these byproducts of biomass burning affects the nearby marine ecosystem in the California Current System (CCS). This project would investigate, using satellite, in-situ and historical data, and 2-D idealized and 3-D realistic modeling. If wildfires indeed induce blooms in the CCS, there are likely impacts on subsurface hypoxia and acidification, which can feed back into higher trophic levels. The efforts proposed in this project will facilitate improved understanding of the feedbacks between the terrestrial-ocean system, which can further be used to inform IPCC assessments of the impacts of future climate forcing on the CCS and other coastal systems with large wildfires. This work may additionally be important for the long-term management of marine protected areas. The PI is a first-generation college student and a woman of color, who will serve as a visible role model within the ocean sciences community, mentor undergraduate students and graduate researchers at UCSC, engage in guest lecturing and teaching, to help promote the retention of students from historically marginalized groups, and participate in local outreach events to engage with the community and aspiring young scientists at UCSC's Seymour Marine Discovery Center. A major hypothesis in this project is that the first order effects from ash deposition drive strong phytoplankton blooms as a consequence of nutrient and iron fertilization. Goals are to: (1) identify the presence of wildfire induced blooms in the CCS, (2) parameterize wildfire forcing through ash deposition in models, and (3) provide a mechanistic understanding of ecosystem responses. With mentor Dr. Christopher Edwards at the University of California – Santa Cruz, the project would use a combination of atmospheric and oceanic observational data sets to first identify the observed impact of biomass burning on the marine ecosystem. To further the results from the observational work, idealized 2D modeling will be used to create a new wildfire parameterization to understand ecosystem responses. Finally, high resolution 3D models will be used to investigate the 2017/2018 wildfire season in a realistic framework. Overall, the project will provide quantitative assessments and simple theories explaining the ecosystem responses to biomass burning. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.