Factors affecting the bacterial community composition and heterotrophic production of Columbia River estuarine turbidity maxima
- NSF Science & Technology Center for Coastal Margin Observation & Prediction (CMOP), Portland, OR (United States); Oregon Health & Science Univ., Portland OR, (United States). Inst. of Environmental Health; DOE/OSTI
- NSF Science & Technology Center for Coastal Margin Observation & Prediction (CMOP), Portland, OR (United States); Oregon State Univ., Corvallis OR (United States). College of Earth, Ocean, and Atmospheric Sciences
- NSF Science & Technology Center for Coastal Margin Observation & Prediction (CMOP), Portland, OR (United States); Univ. of Maryland Center for Environmental Science, Cambridge MD (United States)
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- NSF Science & Technology Center for Coastal Margin Observation & Prediction (CMOP), Portland, OR (United States)
- NSF Science & Technology Center for Coastal Margin Observation & Prediction (CMOP), Portland, OR (United States); Institute of Environmental Health, Oregon Health & Science University, Portland, OR (United States)
Estuarine turbidity maxima (ETM) function as hotspots of microbial activity and diversity in estuaries, yet, little is known about the temporal and spatial variability in ETM bacterial community composition. To determine which environmental factors affect ETM bacterial populations in the Columbia River estuary, we analyzed ETM bacterial community composition (Sanger sequencing and amplicon pyrosequencing of 16S rRNA gene) and bulk heterotrophic production (3H-leucine incorporation rates). We collected water 20 times to cover five ETM events and obtained 42 samples characterized by different salinities, turbidities, seasons, coastal regimes (upwelling vs. downwelling), locations, and particle size. Spring and summer populations were distinct. All May samples had similar bacterial community composition despite having different salinities (1–24 PSU), but summer non-ETM bacteria separated into marine, freshwater, and brackish assemblages. Summer ETM bacterial communities varied depending on coastal upwelling or downwelling conditions and on the sampling site location with respect to tidal intrusion during the previous neap tide. In contrast to ETM, whole (>0.2 μm) and free-living (0.2–3 μm) assemblages of non-ETM waters were similar to each other, indicating that particle-attached (>3 μm) non-ETM bacteria do not develop a distinct community. Brackish water type (ETM or non-ETM) is thus a major factor affecting particle-attached bacterial communities. Heterotrophic production was higher in particle-attached than free-living fractions in all brackish waters collected throughout the water column during the rise to decline of turbidity through an ETM event (i.e., ETM-impacted waters). However, free-living communities showed higher productivity prior to or after an ETM event (i.e., non-ETM-impacted waters). This study has thus found that Columbia River ETM bacterial communities vary based on seasons, salinity, sampling location, and particle size, with the existence of three particle types characterized by different bacterial communities in ETM, ETM-impacted, and non-ETM-impacted brackish waters. Taxonomic analysis suggests that ETM key biological function is to remineralize organic matter.
- Research Organization:
- Pacific Northwest National Lab (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC); National Science Foundation (NSF)
- Grant/Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1623574
- Journal Information:
- MicrobiologyOpen, Journal Name: MicrobiologyOpen Journal Issue: 6 Vol. 6; ISSN 2045-8827
- Publisher:
- WileyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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