2026-08-19 カリフォルニア大学サンタバーバラ校（UCSB）
Photo Credit:PLOS Water
Spatial data coverage for FIB sites, with coastal sites in yellow
＜関連情報＞
- https://news.ucsb.edu/2026/022763/researchers-link-wildfires-californias-coastal-watersheds-water-quality-beach
- https://journals.plos.org/water/article?id=10.1371/journal.pwat.0000589
カリフォルニアの山火事に対する沿岸水域の細菌の反応：20年間の調査 Coastal water bacterial responses to wildfires in California: A twenty-year investigation
Carl Swindle ,Jean Carlson
PLOS Water Published: August 19, 2026
DOI:https://doi.org/10.1371/journal.pwat.0000589
Abstract
This work integrates spatiotemporal datasets in California over a twenty-year period (2003–2023) to identify links between anomalies in fecal indicator bacteria (FIB) — Escherichia coli, total coliforms, fecal coliforms, and Enterococcus — in coastal areas and the occurrence of recent wildfires. Average FIB concentrations, land cover, precipitation, and burn histories are quantified for every month across all watersheds flowing into the California Coast. Monthly non-burn background FIB concentrations are calibrated in coastal areas and define local baselines. FIB anomalies are identified relative to local baselines for both burn periods (>10% of the watershed burned within a two-year window) and non-burn periods and are reported as the anomalous FIB concentrations normalized by the local baseline concentrations. Correlations between FIB anomalies and monthly precipitation and land cover fractions are identified by comparing data from all watersheds impacted by large fires. During burn periods, anomalous total coliform concentrations relative to baseline values (anomalies) exhibit a negative correlation with urban and positive correlations with coastal oak woodland, mixed chaparral, and redwood land cover fraction and monthly precipitation. Burn-period fecal coliform anomalies exhibited a positive correlation with urban land cover fraction. Positive correlations between burn-period total coliform anomalies and monthly precipitation and coastal oak woodland land cover, negative correlations between burn-period total coliform anomalies and urban land cover, positive correlations between burn-period Escherichia coli anomalies and mixed chaparral land cover, and negative correlations between burn-period Escherichia coli anomalies and redwood land cover survive the Benjamini–Hochberg false discovery rate correction. Results indicate prominent post-fire export of total coliform bacteria (perhaps from decaying plant material and soils) in watersheds with less urbanization, and prominent export of fecal coliform bacteria from humans and animals in urbanized watersheds to coastal waters. This is the first effort to generalize post-fire FIB responses in coastal waters. Results may inform future risk assessments.
