Work

Microbial community response and recovery through an aeration-cessation time series in a eutrophic estuary

Year: 2026

Type: preprint

Abstract: Eutrophication-driven hypoxia and harmful algal blooms are an expanding threat to water quality in estuaries. Engineered aeration is a technology used in freshwater and, to a lesser extent, estuarine systems to mitigate both hypoxia and algal blooms. However, the efficacy of engineered aeration has not been well studied within estuarine ecosystems and very little is known about the impact of aeration on microbial communities in either estuarine or freshwater environments. Here we present a time series investigation of microbial community response to aeration and cessation of aeration in a eutrophic estuary. Samples for 16S rRNA gene analysis were collected over about a month-long period during which time the aerators transitioned from being “on” to “off” to “on” again. Cessation of aeration selected for the dominance of a eukaryotic algae similar to Heterosigma akashiwo . After the resumption of aeration, H. akashiwo dominance decreased rapidly. Cessation of aeration also shifted the structure of the entire microbial community, where diversity decreased and the structure of microbial communities at the surface diverged from those from the bottom of the water column. These changes did not occur at non-aerated control sites. Distinct groups of taxa responded to the disruption in a successional pattern through time, with most taxa never returning to their pre-aeration-cessation abundance during the observational period. These findings demonstrate the complex community response to anthropogenic interventions and provide support for bloom suppression through aeration. Importance Hypoxia and algal blooms represent a severe and growing threat to the economies of coastal communities. Engineered aeration has been well studied as a tool to mitigate hypoxia and algal blooms in freshwater systems, but little is known about its efficacy in estuarine systems or its impact on the whole microbial community. Our results demonstrate that, within a eutrophic estuary, aeration mitigates hypoxia, suppresses algal blooms, and significantly alters the broader microbial community structure. Stopping aeration dramatically restructures microbial community composition, and these microorganisms don’t immediately recover after two weeks of altered oxygen conditions. This work shows that engineered aeration is an effective tool maintain water local quality in small estuaries, but also offers the warning that any cessation, such as from failures or planned outages, can cause large disruptions to microbial communities and may lead to rapid algal bloom formation.

Source: bioRxiv (Cold Spring Harbor Laboratory)

DOI: 10.64898/2026.09.24.754275