Bacterial response to the 2021 Orange County, California, oil spill was episodic but subtle relative to natural fluctuations

ABSTRACT An oil spill began in October 2021 off the coast of Orange County, California, releasing 24,696 gallons of crude oil into 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 seve...

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Main Authors: Melissa L. Brock, Joana F. Tavares-Reager, Jialin Dong, Alyse A. Larkin, Toan Lam, Nataly Pineda, Christopher I. Olivares, Katherine R. M. Mackey, Adam C. Martiny
Format: Article
Language:English
Published: American Society for Microbiology 2025-05-01
Series:Microbiology Spectrum
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Online Access:https://journals.asm.org/doi/10.1128/spectrum.02267-24
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author Melissa L. Brock
Joana F. Tavares-Reager
Jialin Dong
Alyse A. Larkin
Toan Lam
Nataly Pineda
Christopher I. Olivares
Katherine R. M. Mackey
Adam C. Martiny
author_facet Melissa L. Brock
Joana F. Tavares-Reager
Jialin Dong
Alyse A. Larkin
Toan Lam
Nataly Pineda
Christopher I. Olivares
Katherine R. M. Mackey
Adam C. Martiny
author_sort Melissa L. Brock
collection DOAJ
description ABSTRACT An oil spill began in October 2021 off the coast of Orange County, California, releasing 24,696 gallons of crude oil into 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 severity of the local bacterial response. A coastal 10-year time series of short-read metagenomes located within the impacted area allowed us to quantify the magnitude and duration of the disturbance relative to natural fluctuations. We found that the largest change in bacterial beta-diversity occurred at the end of October. The change in taxonomic beta-diversity corresponded with an increase in the sulfur-oxidizing clade Candidatus Thioglobus, an increase in the total relative abundance of potential hydrocarbon-degrading bacteria, and an anomalous decline in the picocyanobacteria Synechococcus. Similarly, changes in function were related to anomalous declines in photosynthetic pathways and anomalous increases in sulfur metabolism pathways as well as aromatic degradation pathways. There was a lagged response in taxonomy and function to peaks in total PAHs. One week after peaks in total PAH concentrations, the largest shifts in taxonomy were observed, and 1 week after the taxonomy shifts were observed, unique functional changes were seen. This response pattern was observed twice during our sampling period, corresponding with the combined effect of resuspended PAHs and increased nutrient concentrations due to physical transport events. Thus, the impact of the spill on bacterial communities was temporally extended and demonstrates the need for continued monitoring for longer than 3 months after initial oil exposure.IMPORTANCEOil spills are common occurrences in waterways, releasing contaminants into the aquatic environment that persist for long periods of time. Bacterial communities are rapid responders to environmental disturbances, such as oil spills. Within bacterial communities, some members will be susceptible to the disturbance caused by crude oil components and will decline in abundance, whereas others will be opportunistic and will be able to use crude oil components for their metabolism. In many cases, when an oil spill occurs, it is difficult to assess the oil spill’s impact because no samples were collected prior to the accident. Here, we examined the bacterial response to the 2021 Orange County oil spill using a 10-year time series that lies within the impacted area. The results presented here are significant because (i) susceptible and opportunistic taxa to oil spills within the coastal California environment are identified and (ii) the magnitude and duration of the in situ bacterial response is quantified for the first time.
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spelling doaj-art-5fd31d68aeef412dad7dbca2c255c2ec2025-08-20T03:11:48ZengAmerican Society for MicrobiologyMicrobiology Spectrum2165-04972025-05-0113510.1128/spectrum.02267-24Bacterial response to the 2021 Orange County, California, oil spill was episodic but subtle relative to natural fluctuationsMelissa L. Brock0Joana F. Tavares-Reager1Jialin Dong2Alyse A. Larkin3Toan Lam4Nataly Pineda5Christopher I. Olivares6Katherine R. M. Mackey7Adam C. Martiny8Department of Ecology and Evolutionary Biology, University of California at Irvine, Irvine, California, USADepartment of Earth System Science, University of California at Irvine, Irvine, California, USADepartment of Civil and Environmental Engineering, University of California at Irvine, Irvine, California, USADepartment of Earth System Science, University of California at Irvine, Irvine, California, USASchool of Biological Sciences, University of California at Irvine, Irvine, California, USADepartment of Earth System Science, University of California at Irvine, Irvine, California, USADepartment of Civil and Environmental Engineering, University of California at Irvine, Irvine, California, USADepartment of Ecology and Evolutionary Biology, University of California at Irvine, Irvine, California, USADepartment of Ecology and Evolutionary Biology, University of California at Irvine, Irvine, California, USAABSTRACT An oil spill began in October 2021 off the coast of Orange County, California, releasing 24,696 gallons of crude oil into 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 severity of the local bacterial response. A coastal 10-year time series of short-read metagenomes located within the impacted area allowed us to quantify the magnitude and duration of the disturbance relative to natural fluctuations. We found that the largest change in bacterial beta-diversity occurred at the end of October. The change in taxonomic beta-diversity corresponded with an increase in the sulfur-oxidizing clade Candidatus Thioglobus, an increase in the total relative abundance of potential hydrocarbon-degrading bacteria, and an anomalous decline in the picocyanobacteria Synechococcus. Similarly, changes in function were related to anomalous declines in photosynthetic pathways and anomalous increases in sulfur metabolism pathways as well as aromatic degradation pathways. There was a lagged response in taxonomy and function to peaks in total PAHs. One week after peaks in total PAH concentrations, the largest shifts in taxonomy were observed, and 1 week after the taxonomy shifts were observed, unique functional changes were seen. This response pattern was observed twice during our sampling period, corresponding with the combined effect of resuspended PAHs and increased nutrient concentrations due to physical transport events. Thus, the impact of the spill on bacterial communities was temporally extended and demonstrates the need for continued monitoring for longer than 3 months after initial oil exposure.IMPORTANCEOil spills are common occurrences in waterways, releasing contaminants into the aquatic environment that persist for long periods of time. Bacterial communities are rapid responders to environmental disturbances, such as oil spills. Within bacterial communities, some members will be susceptible to the disturbance caused by crude oil components and will decline in abundance, whereas others will be opportunistic and will be able to use crude oil components for their metabolism. In many cases, when an oil spill occurs, it is difficult to assess the oil spill’s impact because no samples were collected prior to the accident. Here, we examined the bacterial response to the 2021 Orange County oil spill using a 10-year time series that lies within the impacted area. The results presented here are significant because (i) susceptible and opportunistic taxa to oil spills within the coastal California environment are identified and (ii) the magnitude and duration of the in situ bacterial response is quantified for the first time.https://journals.asm.org/doi/10.1128/spectrum.02267-24metagenomicsdisturbance ecologyrecoverycoastalplanktonic
spellingShingle Melissa L. Brock
Joana F. Tavares-Reager
Jialin Dong
Alyse A. Larkin
Toan Lam
Nataly Pineda
Christopher I. Olivares
Katherine R. M. Mackey
Adam C. Martiny
Bacterial response to the 2021 Orange County, California, oil spill was episodic but subtle relative to natural fluctuations
Microbiology Spectrum
metagenomics
disturbance ecology
recovery
coastal
planktonic
title Bacterial response to the 2021 Orange County, California, oil spill was episodic but subtle relative to natural fluctuations
title_full Bacterial response to the 2021 Orange County, California, oil spill was episodic but subtle relative to natural fluctuations
title_fullStr Bacterial response to the 2021 Orange County, California, oil spill was episodic but subtle relative to natural fluctuations
title_full_unstemmed Bacterial response to the 2021 Orange County, California, oil spill was episodic but subtle relative to natural fluctuations
title_short Bacterial response to the 2021 Orange County, California, oil spill was episodic but subtle relative to natural fluctuations
title_sort bacterial response to the 2021 orange county california oil spill was episodic but subtle relative to natural fluctuations
topic metagenomics
disturbance ecology
recovery
coastal
planktonic
url https://journals.asm.org/doi/10.1128/spectrum.02267-24
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