Recurrent bacterial response to the 2021 Orange County, California oil spill

An oil spill occurred off the coast of Orange County, California in October 2021, releasing 24,696 gallons of crude oil into southern California’s coastal environments. Although oil spills, such as this one, are recurrent accidents along the California coast, no prior studies have been performed to examine the in-situ bacterial response. A coastal 10-year time-series of short-read bacterial metagenomes located within the impacted area provided an opportunity for quantifying the magnitude and duration of the bacterial taxonomic and functional response. We found that the largest change in taxonomic and functional beta-diversity occurred at the end of October 2021, 3 – 4 weeks after the oil spill began. The change in taxonomic beta-diversity corresponded with an anomalous decline in the picocyanobacteria Synechococcus, an increase in the sulfur-oxidizing clade Candidatus Thioglobus, and an increase in total potential hydrocarbon-degrading bacteria. Similarly, changes in function were related to anomalous declines in photosynthetic pathways, increases in sulfur metabolism pathways, and increases in aromatic degradation pathways. Interestingly, the bacterial response exhibited a one-week lag to peaks in total polycyclic aromatic hydrocarbon concentrations (PAH). This pattern of response was observed twice during our sampling period and corresponded with the resuspension of PAHs after physical transport events (e.g., upwelling). Thus, we observed important links between physical circulation, contaminant levels, and the biological response as well as demonstrated that the persistence of crude oil components extended the temporal impact of the oil spill resulting in a pulsed biological response.

Presentation Preference: Oral

Primary Presenter: Melissa Brock, University of California - San Diego (mlbrock@ucsd.edu)

Authors:

Melissa Brock, University of California - Irvine  (mlbrock@uci.edu)

Joana Tavares-Reager, University of California - Irvine  (tavaresj@uci.edu)

Jialin Dong, University of California - Irvine  (jialind2@uci.edu)

Alyse Larkin, National Oceanic and Atmospheric Administration  (alyse.larkin@noaa.gov)

Toan Lam, University of California - Irvine  (toantl1@uci.edu)

Nataly Pineda, University of California - Irvine  (npineda2@uci.edu)

Christopher Olivares, University of California - Irvine  (chris.olivares@uci.edu)

Katherine Mackey, University of California - Irvine  (kmackey@uci.edu)

Adam Martiny, University of California - Irvine  (amartiny@uci.edu)