Natural, episodic processes such as eddies, fronts, upwelling, storms, hurricanes, as well as irregular anthropogenic-driven oil spills or pollutant release are common disturbances in marine and limnetic ecosystems. These processes occur at fine-scale temporal and/or spatial resolution and thus are not currently resolved in modern Earth System Models that are used to project future climate scenarios. Many of these processes are becoming more frequent and are intensifying under ongoing climate change, so it is increasingly important to understand their effects. These events disproportionately impact aquatic systems by providing anomalous “pulses” of nutrients or an altered physical environment that microbial communities respond to. However, the impact of such pulses on microbial communities is difficult to capture and synthesize because of variable characteristics of the physical disturbance, rapid changes to biogeochemistry, and potentially unknown pre-existing local environmental conditions. In this session, we invite submissions that quantitatively link episodic or irregular fine-scale forcings with geochemical changes and the microbial response (bacteria, archaea, and/or eukaryotes) within marine and limnetic ecosystems. We highly encourage submissions that use observational surveys of microbial communities (e.g., ‘omics, flow cytometry, and microscopy) to perform a detailed assessment of the biological response to pulsed physical disturbances. Of particular interest are examinations of the duration of the microbial response to the disturbance, the variability of the response to a particular type of disturbance, a comparison of the response between different types of disturbances, or links between changes within the microbial community to changes in ecosystem level processes.
Lead Organizer: Melissa Brock, University of California - San Diego (mlbrock@uci.edu)
Co-organizers:
Alexandra Jones-Kellett, Massachusetts Institute of Technology (jonesae@mit.edu)
Christopher Olivares, University of California - Irvine (chris.olivares@uci.edu)
Presentations
04:30 PM
SURFACE WATER MICROBIOME RESPONSE TO PYROGENIC CARBON AFTER A WILDLAND-URBAN INTERFACE FIRE (9384)
Tutorial/Invited: Invited
Primary Presenter: Lyssa Morgan, University of California, Irvine (lemorgan@uci.edu)
The increase in wildfire season duration, severity, and frequency in wildland-urban interfaces (WUI) is a global concern due to expanding human development. Post-fire storms can introduce pulses of pyrogenic organic contaminants into surface waters, but the dynamics between microbial communities and pyrogenic contaminants in WUI post-fire storm runoff are less understood. We studied a stream adjacent to a WUI fire in Orange County, CA, for organic contaminants, microbial community composition, and their predicted function immediately after the fire and during the following winter storms. The first rains after the fire were of low intensity and showed the highest discharges of smaller polycyclic aromatic hydrocarbons (PAHs) of concern, including benzo[a]pyrene (54.2 ppb, 64.8 ppb) and benz[a]anthracene (1.27 ppb, 1.23 ppb). However, dissolved organic carbon discharge reached a maximum average loading rate of 11.2 g C/s during later severe rain events. PAH concentrations were strongly correlated with each other but not with carbon loading rate. PAH concentration patterns did not match turbidity data, suggesting turbidity may be a poor water quality indicator of pyrogenic carbon. Several microbial taxa known to degrade PAHs, including Acinetobacter, Sphingobium, Massilia, Chitinophagaceae, Pedobacter, and Sphingomonas, were differentially abundant during the rainy period. Additionally, predicted metabolic pathways related to PAH biodegradation and transformation products such as catechol and protocatechuate were significantly up-regulated directly downstream of the fire. These findings highlight how episodic fire events create contaminate pulses that drive shifts in microbial community function favoring putative PAH degrading microorganisms in storms months after the fire without additional remediation amendments.
04:45 PM
Recurrent bacterial response to the 2021 Orange County, California oil spill (9394)
Primary Presenter: Melissa Brock, University of California - San Diego (mlbrock@ucsd.edu)
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.
05:00 PM
GENOME RESOLVED PROFILING OF MICROBIAL HYDROCARBON DEGRADATION PATHWAYS ACROSS SPATIAL-TEMPORAL GRADIENTS IN ESTUARINE ECOSYSTEMS (9177)
Primary Presenter: Dinuka Jayasuriya, Clemson University (djayasu@g.clemson.edu)
Hydrocarbons are recalcitrant organics that can be released into the environment via natural and anthropogenic activities. Microorganisms have the potential ability to degrade a wide range of hydrocarbons through various metabolic pathways, which can be influenced by both abiotic and biotic factors, including environmental, microbial and hydrocarbon properties. We hypothesized that abiotic and biotic factors, including salinity, temperature, particle attachment, and microbial interactions, regulate the genome abundance of hydrocarbon degraders in the Delaware and Chesapeake Bays. We identified hydrocarbon degradation pathways by screening for essential genes in 360 estuarine-derived MAGs. Gene and transcript abundances were assessed, revealing critical genes involved in hydrocarbon degradation. Nanopelagicales were most abundant in mid to high salinity Chesapeake Bay samples, while Pseudomonadales dominated mid to high salinity Delaware Bay samples in spring. Chitinophagales were the most abundant and active in mid-salinity spring Delaware Bay samples. Burkholderiales were found in low to mid salinity in both bays during summer and fall, with higher gene expression in low salinity spring Chesapeake Bay samples. Flavobacteriales were more active in mid-salinity fall Delaware Bay samples than their abundance suggested. The catechol degradation pathway was prominent in spring low-salinity samples in both bays. In conclusion, hydrocarbon degradation genes are expressed in response to specific environmental conditions, including season and salinity changes.
05:15 PM
DISENTANGLING THE EFFECTS OF PULSE DISTURBANCES FROM LANDSCAPE MODIFICATIONS IN AN IRON ORE TAILING CONTAMINATED TROPICAL RIVER (9349)
Primary Presenter: Arthur Silva-Lima, Universidade Federal do Rio de Janeiro (arthurwlima@gmail.com)
The Paraopeba river is an important water resource in Brazil, influenced by the country’s third most populous area, the Belo Horizonte Metropolitan Region (BHMR). In January 2019 a mass deposition of iron ore tailings affected the river bed. Here, we present a data-driven approach to disentangle the effects of pulse disturbances, caused by the deposition and the seasonal remobilization of iron ore tailings, from the effects of anthropogenic landscape modification on the BHMR. Historical data was used to determine the environmental signatures of the ore tailings deposit (enrichment in iron and manganese) and the BHMR (water conductivity, oxygen concentration, and fecal bacterial indicators) in the Paraopeba water. Despite the geographical coincidence, different microbial consortia can be associated with the ore tailings and with the BHMR. Interannual and seasonal variations on manganese concentrations in the water are consistent with the expectation of a pulse disturbance, with a downstream displacement of the environmental signature. Our results highlight the importance of continuous surveillance of water bodies for the determination of impacts due to environmental disasters, enabling the quantification of the effects of pulse perturbations even in the presence of other anthropogenic pressures in the river landscape.
05:30 PM
MARINE PLASTISPHERE STRUCTURE AND FUNCTION: INSIGHTS FROM A FLOW-THROUGH EXPERIMENT ON MICROPLASTICS IN THE WATER COLUMN (8879)
Primary Presenter: Astrid Zapata De Jesus, University of New Hampshire (astridzzapata@gmail.com)
The ongoing presence of microplastics in coastal oceans has revealed the existence of a plastisphere, where microbial communities significantly differ from those in surrounding water environments, highlighting the potential impacts on biogeochemical processes in the water column. On this study, polyethylene microplastics were added to a natural sea water flow-through system over 23 days. Our main goal was to determine the effects of microplastics on biofilm formation and associated changes in community structure and functions, by means of selected hydrolytic enzyme activities of natural microbial assemblages over the time course of the experiment. We hypothesized that microplastics select for distinct microbial communities that exhibit enzymatic activities compared with microbes attached to natural particles. Biofilm formation on microplastics can influence microbial activity in the water column, potentially modifying the aggregation and sinking dynamics of particulate matter, intervening in the natural process of the ocean carbon cycle. Main results indicated that biofilm concentration around microplastics increased by more than 100% over the sampling period. Microplastics were analyzed for bacterial cell abundance, total community structure (16S rRNA gene sequencing), and potential activities of seven hydrolytic enzymes as indicators of microbial breakdown of lipids, carbohydrates, and peptides. Our preliminary results have shown microbial succession in biofilms formed around microplastics, along with community specificity at a family-level compared to natural particles. The analysis of our results could provide insights into whether microplastics serve as a carbon source for microbial communities in the water column, potentially altering nutrient cycles in coastal waters. If confirmed, further research into the broader impacts on oceanic elemental cycles will be necessary.
05:45 PM
Investigating the correspondence between environmental variation, abundance, and interspecies competition of a globally significant echinoderm pathogen (8764)
Primary Presenter: Ian Hewson, Cornell University (hewson@cornell.edu)
Diadematidae scuticociliatosis (DSc) is an emerging and globally distributed threat to keystone herbivorous urchins within coral reef habitats. The condition is caused by the DSc Philaster clade (DScPc), which has also been observed on the surfaces of sympatric corals, sponges and macroalgae at the time of mass mortality and for months afterwards. Key questions remain around factors resulting in its emergence, overlapping distribution with coral diseases, and how environmental variation and interspecific competition affect DScPc dynamics. We performed a time series analysis of DScPc and related ciliate taxa at a single site (Vaca Key, Florida) over 18 months in plankton and surfaces of corals, sponges, and macroalgae in association with physicochemical parameters and chlorophyll a. We found that DScPc was detected on surfaces in springtime, concomitant with enhanced macroalgal cover, but was largely replaced by a related species of Philaster into summer. DScPc was detected in the water column at the same site in late Fall through Spring, where the related species was detected in Spring into Summer. DScPc consumed zooxanthellae, retaining their chloroplasts, in culture-based experiments. Together, these data suggest that the DScPc associates with springtime primary production, which may result from consumption of dissolved or particulate organic matter derived from primary production. Furthermore, consumption of zooxanthellae leads to interesting questions about the association between bleaching and other coral diseases and DSc-Philaster emergence.
SS09C - Microbial responses to pulse disturbances in aquatic environments
Description
Time: 4:30 PM
Date: 30/3/2025
Room: W205CD