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Aquatic Microbial Ecology

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AME 72:17-31 (2014)  -  DOI:

Impacts of freshwater flushing on anammox community structure and activities in the New River Estuary, USA

Jessica A. Lisa1, 2,4,*, Bongkeun Song1,2,4,*, Craig R. Tobias3, Kimberley A. Duernberger2

1Department of Biology and Marine Biology, and 2Center for Marine Science, University of North Carolina Wilmington, North Carolina 28403, USA
3Department of Marine Sciences, University of Connecticut, Connecticut 06269, USA
4Present address: Virginia Institute of Marine Science, College of William & Mary, PO Box 1346, Gloucester Point, Virginia 23062, USA
*Corresponding author:

ABSTRACT: Anaerobic ammonium oxidation (anammox) and denitrification are 2 microbial nitrogen removal processes that may play an important role in controlling the intensity and duration of estuarine and coastal eutrophication. Sediment communities in the New River Estuary, North Carolina were investigated to determine the dynamics of anammox activity and community structure in conjunction with environmental conditions. 15N tracer incubation experiments with sediment slurries were used to measure anammox and denitrification rates and estimate anammox contribution to total N2 production. Molecular analyses targeting the hydrazine oxidoreductase (hzo) gene were conducted to examine the structure of anammox communities and quantify the abundance of anammox bacteria in sediments. Potential anammox rates ranged from 0.02 to 1.4 nmol N2 g-1 h-1, with the highest potential activities observed during winter and spring when the estuary received large doses of nitrogen from the watershed. Anammox contributed up to 14.1% of total N2 production in upstream estuarine sediments and abundance of anammox communities ranged from 1.55 × 102 to 2.59 × 105 hzo gene copies g-1 sediment. Both activities and abundance of anammox communities were correlated with percent sediment organics (%organics) and the porewater concentrations of hydrogen sulfide. Based on hzo sequence analysis, anammox bacteria related to ‘Candidatus Jettenia spp.’ were widespread in estuarine sediments, which may be attributed to freshwater flushing and associated changes in environmental parameters as well as the geomorphology of the estuary. This is the first study to describe a dominance of ‘Candidatus Jettenia spp.’ in relation to %organics and hydrogen sulfide in an estuarine ecosystem driven by meteorological forcing.

KEY WORDS: Anammox · ‘Candidatus Jettenia spp.’ · ‘Candidatus Scalindua spp.’ · hzo genes · New River Estuary

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Cite this article as: Lisa JA, Song B, Tobias CR, Duernberger KA (2014) Impacts of freshwater flushing on anammox community structure and activities in the New River Estuary, USA. Aquat Microb Ecol 72:17-31.

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