Rivers and lakes are integral components of hydrological networks that regulate the flow of water, energy, and materials across the landscape. While these ecosystems provide crucial services to living organisms, they are increasingly threatened by human activities, such as changes in land use, hydrological modifications, pollution, agricultural runoff, and urban wastewater discharge. The response of freshwater microbial biodiversity to these anthropogenic pressures along aquatic continua is the central theme of discussion in this session. We invite presenters whose research links microbial communities with longitudinal changes along aquatic continua. Presentations will encompass a diverse range of systems and approaches. For instance, the metagenomic characterization of freshwater micro-organisms along a land use gradient could provide insights into how urbanization in watersheds alters microbial biodiversity in streams. Comparisons of microbiomes along river-lake continua across seasons will shed light on the biogeochemical consequences of flow alteration. Mechanisms driving plankton succession will be discussed to evaluate whether spatial overwhelms “the widely known” seasonal succession of plankton in river-lake continua. Presenters will also contextualize their findings broadly and identify critical gaps in knowledge and future research directions. The collective expertise of participants spanning freshwater macro- and microbial ecology, biogeochemistry, hydrology, modeling, and molecular approaches will facilitate valuable interdisciplinary exchanges.
Lead Organizer: Alain Isabwe, Cooperative Institute for Great Lakes Research (CIGRL), School for Environment and Sustainability, University of Michigan, Ann Arbor (aisabwe@umich.edu)
Co-organizers:
Sophie Crevecoeur, Watershed Hydrology and Ecology Research Division, Environment and Climate Change Canada (Sophie.crevecoeur@ec.gc.ca)
Presentations
09:00 AM
The Impact of Wastewater Effluent on the Carapace Microbiome of an Invasive Crayfish in an Urban River. (8045)
Primary Presenter: Grant Dlesk, Loyola University Chicago (gdlesk@luc.edu)
Microbial communities are ubiquitous and highly variable in aquatic environments, especially within urbanized waterbodies routinely exposed to effluent, runoff, and other forms of anthropogenic pollution. The North Shore Channel (NSC) is a drainage canal connecting Lake Michigan to the North Branch of the Chicago River that receives effluent from a wastewater treatment plant (WWTP). The NSC contains a large population of red swamp crayfish (Procambarus clarkii), a globally known and harmful invader. The high density of red swamp crayfish below the WWTP represents a potential vector for spreading pathogenic bacteria from the effluent to humans and other aquatic species. We collected bacterial communities from crayfish carapaces, sediment, and water, each from above and below the WWTP. We analyzed these communities using a 16S rRNA sequencing approach. We calculated the Shannon diversity index for each sample and grouped samples based on their distance from the WWTP. We performed ANOVA for each sample type between the upstream samples and two groups below the WWTP. Crayfish and water samples showed a significant relationship between alpha diversity and distance from the WTTP (p-value < 0.001), while sediment samples did not have a significant relationship (p-value 0.613). We also identified several genera within the crayfish samples that are known to contain pathogens. Our results show that the WWTP is a major factor driving the diversity within the carapace bacterial communities of red swamp crayfish in the North Shore Channel.
09:15 AM
MICROBIAL COMMUNITY PATTERNS ALONG A VEGETATION AND SALINITY GRADIENT IN MOBILE BAY ESTUARY, AL, USA: IMPLICATIONS FOR WETLAND ECOSYSTEM FUNCTIONS (8400)
Primary Presenter: Eric Weingarten, U.S. Army Engineer Research and Development Center (microbialdiveric@gmail.com)
Tidal wetlands host biodiversity, serve as barriers to storm surge, and are integral regulators of nitrogen, phosphorus, and sulfur cycling. Estuaries are critical to carbon storage and greenhouse gas production, balancing mineralization and burial of organic matter. We describe soil physicochemical and microbial diversity along a vegetation and salinity gradient in the Mobile Bay estuary, AL, USA – the sixth largest watershed in the US – and discuss how these factors feedback on ecosystem characteristics and the delivery of ecological functions. We incorporated microbial trait data including biomass, diversity, community composition, and inferred functions into patterns of coastal vegetation occurrence, salinity, sediment C/N/P/S content, and extracellular enzyme activities spanning the organic and mineral soil horizons. Modeling these parameters showed that vegetation type >> soil horizon > and salinity strongly influenced microbe-soil relationships. All biotic and abiotic factors indicated that tidal freshwater forested wetlands represent a distinct biome within the Mobile Bay estuary, distinct from zonation of increasingly salt-tolerant Typha, tidal shrub, and Juncus, which are considered “emergent marsh”. Forested wetlands contained 80% less organic carbon content, 75% less nitrogen, 33% less phosphorus, and 95% less sulfur than emergent marsh, correlating closely with a unique microbial community. Integration of biological diversity, enzymatic, and geochemical data layers are important steps to incorporating microbial trait data into soil carbon models in wetlands.
09:30 AM
Riverine plankton community assembly in an urbanizing watershed (8431)
Primary Presenter: Alain Isabwe, University of Michigan (aisabwe@gmail.com)
Understanding the relative importance of – and the interactions between – ecological mechanisms underlying distribution patterns and successional dynamics of freshwater plankton communities is a central problem that remains unsolved in microbial ecology. We complemented variation partitioning analysis, neutral community model, and quantitative process estimate on molecular and morphological plankton data obtained over a five-year sampling campaign in Houxi River, China. The similarity in both bacterioplankton and phytoplankton across the sites decreased with increasing distance from the upstream to the river mouth and formed clusters that roughly match the urban-induced habitat modification and fragmentation. Thus urbanization, through which construction of dams and human-driven biotic and abiotic inputs take place might have caused habitat fragmentation by forming ecoclines of longitudinally connected ecotones. Functional community structure was slightly different between the reservoir and river sites. These results highlighted that human-induced hydrological change and anthropogenic pollution in the studied river system did not only constrain dispersal but also taxonomic and functional attributes of the riverine plankton communities.
09:45 AM
Beyond the Plate: Spillover of antimicrobial resistance to wild populations (8114)
Primary Presenter: Chloé Fouilloux, University of Wisconsin, Madison (fouilloux@wisc.edu)
Antimicrobial resistance (AMR) is a global health challenge that threatens the foundation of modern medicine. Globally, the agricultural sector accounts for over half of administered antibiotics. In aquatic systems, where there is no division between farmed and wild space, the spillover of pollutants from commercial fisheries increasingly challenges ecosystem health, although the consequences of these patterns remain poorly understood. Here, we combine functional genomics and modeling techniques to investigate the impact of AMR on wild fish populations of the three-spined stickleback (Gasterosteus aculeatus) across Vancouver Island. Home to one of the highest concentrations of salmon farms in Canada, Vancouver Island presents a gradient of lakes varying in connectivity to marine farming sites. This ecology allows us to establish potential links between antibiotic-use in managed areas and AMR accumulation in wild fauna. With multiple ecotypes and flexible habitat use, sticklebacks are an ideal animal model to assess AMR accumulation in diverse scenarios. Using next-generation sequencing we first screened the diversity of AMR genes in microbiomes across populations. Then, we quantified co-occurence of the most abundant mutations using ddPCR. Using structural equation modeling, we examined the relative contributions of connectivity to salmon farms, limnological, and land-use metrics on the abundance and diversity of AMR genes. Together, these data move beyond system-specific case studies and provide generalizable knowledge that can be applied to improve fisheries management.
10:00 AM
Mycoplankton response to lake trophic state and phytoplankton community composition in Canadian lakes (8091)
Primary Presenter: Joanna Gauthier, University of Ottawa (gauthier.joanna@gmail.com)
Aquatic fungi are ubiquitous and play essential roles in organic matter decomposition and nutrient cycling in freshwater systems. In plankton, however, they have been largely overlooked, particularly in lakes. Hence, there is a need to evaluate their diversity and community composition on a large spatial scale. Using 18S rRNA gene amplicons from surface water of 369 Canadian lakes sampled across several biomes as part of the NSERC Lake Pulse Network, we examined the diversity and community composition of mycoplankton along a trophic gradient, assessing their potential as indicator species. The dominant fungal group in taxa and sequence numbers belonged to Chytridiomycota, followed by Dikarya. The diversity of fungi declined with increasing total phosphorus, with the greatest difference seen in oligotrophic vs. hypereutrophic lakes. Similarly, fungal community composition varied greatly between oligotrophic and hypereutrophic lakes although only a small proportional (~4-6%) was explained by the change in trophic status. Ions, pH, and land use were identified as drivers of fungal diversity and community composition. Using Co-Inertia analyses, fungal communities had higher correlations with eukaryotic phytoplankton rather than environmental variables, which indicated the importance of parasites in mycoplankton. This study is the first to analyze the diversity and community composition of mycoplankton in lakes on a large spatial scale revealing a high potential of mycoplankton as indicator of phytoplankton composition and other environmental variables.
SS04 - Microbial Patterns and Processes Along Aquatic Continua in the Face of Anthropogenic Disturbances
Description
Time: 9:00 AM
Date: 4/6/2024
Room: Meeting Room KL