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Nitrogen cycling in coastal sediment microbial communities with seasonally variable benthic nutrient fluxes

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posted on 16.04.2021, 05:24 by AJ Marshall, A Longmore, L Phillips, Caixian TangCaixian Tang, HL Hayden, KB Heidelberg, Pauline MelePauline Mele
Benthic microbial communities contribute to nitrogen (N) cycling in coastal ecosystems through taxon-specific processes such as anammox, nitrification and N-fixation and community attributed pathways such as denitrification. By measuring the total (DNA-based) and active (RNA-based) surface sediment microbial community composition and the abundance and activity profiles of key N-cycling genes in a semi-enclosed embayment — Port Phillip Bay (PPB), Australia — we show that although the total relative abundance of N-cycling taxa is comparatively lower close to estuary inputs (Hobsons Bay [HB]), the capacity for this community to perform diverse N-cycling processes is comparatively higher than in sediments isolated from inputs (Central PPB [CPPB]). In HB, seasonal structuring of the sediment microbial community occurred between spring and summer, co-occurring with decreases in the activity profiles of anammox bacteria and organic carbon content. No changes were detected in the activity profiles of nitrifiers or the community-based pathway denitrification. Although no seasonal structuring of the sediment microbial community occurred in CPPB, the activity profiles of key N-cycling genes displayed comparatively higher within-site variability. These results show that despite N-cycling taxa representing a smaller fraction of the total community composition in estuary impacted sediments (HB) these microbial communities consistently engage in N-cycling processes and that seasonal instability in the composition of this community is not reflective of changes in its capacity to cycle N through coupled nitrification−denitrification but potentially via changes within the anammox community.

Funding

This work was supported by Melbourne Water, the Victorian Department of Environment, Land, Water and Planning (DELWP) and the Victorian Department of Jobs, Precincts and Regions (DJPR; Agriculture Victoria Research).This study was supported by an investment proposal to Melbourne Water and the Victorian Department of Environment, Land, Water and Planning.

History

Publication Date

28/01/2021

Journal

Aquatic Microbial Ecology

Volume

86

Pagination

1-19

Publisher

Inter-Research

ISSN

0948-3055

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The Author reserves all moral rights over the deposited text and must be credited if any re-use occurs. Documents deposited in OPAL are the Open Access versions of outputs published elsewhere. Changes resulting from the publishing process may therefore not be reflected in this document. The final published version may be obtained via the publisher’s DOI. Please note that additional copyright and access restrictions may apply to the published version.

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