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Microbial Community Structure in Relation to Water Quality in a Eutrophic Gulf of Mexico Estuary
James, J. AND B. Jarvis. Microbial Community Structure in Relation to Water Quality in a Eutrophic Gulf of Mexico Estuary. ASM Microbe, New Orleans, LA, June 01 - 05, 2017.
Investigation of surface waters in Weeks Bay, AL, correlating the microbial community structure with water conditions. These results provide useful information about microbial and algal community dynamics in estuaries and could be useful in predicting ecosystem function in relation to nutrient loading, water quality, and other seasonal driver.
Weeks Bay is a shallow, microtidal, eutrophic sub-estuary of Mobile Bay, AL. High watershed nutrient inputs to the estuary contribute to a eutrophic condition characterized by frequent summertime diel-cycling hypoxia and dissolved oxygen (DO) oversaturation. Spatial and seasonal variability of microbial communities that contribute to estuarine ecosystem metabolism were characterized using high-throughput DNA sequencing. Surface water samples were collected from spring to fall at three sites along a transect of Weeks Bay from the Fish River to Mobile Bay. Water samples were analyzed for physiochemical properties and were also filtered onto Sterivex filters for DNA extraction. Genes for 16S rRNA and 18S rRNA were amplified and sequenced according to Earth Microbiome Project protocols. Sequences were assembled into contigs and clustered into OTUs with mothur using the Silva database. The prokaryotes were dominated by Cyanobacteria, Actinobacteria, and Spartobacteria, whereas the eukaryotes were dominated by Bacillariophyta (diatoms). Multivariate statistical analysis of microbial community composition and environmental data showed that Bacteria, Archaea and Eukaryota were clustered by season. BEST analysis by station showed that prokaryotic community structure was associated with salinity and CDOM (Rho=0.924), whereas eukaryotic community structure was most associated with salinity (Rho=0.846). Prokaryotic community structure within seasons was associated with six factors (temperature, salinity, CDOM, pH, chlorophyll-a, and ammonium (Rho=0.846)), whereas eukaryotic community structure was associated significantly with five (temperature, DO, CDOM, chlorophyll-a, and TDN (Rho=0.833)). The eukaryotes varied in relation to a different set of water quality factors than did the prokaryotes. These results provide useful information about microbial and algal community dynamics in estuaries like Weeks Bay and could be useful for understanding and predicting ecosystem function in relation to nutrient loading, water quality and other seasonal drivers.