ORCID
0009-0002-6834-8508 (Crider), 0000-0002-5721-3061 (Selden), 0009-0000-7468-4343 (Powell), 0000-0003-0620-2001 (Tuo), 0000-0003-0914-9007 (Muglia), 0009-0004-5578-8832 (Taylor), 0000-0001-8819-189X (Mulholland), 0000-0001-5212-6228 (Chappell)
Document Type
Article
Publication Date
2026
DOI
10.1002/lno.70499
Publication Title
Limnology and Oceanography
Volume
71
Issue
10
Pages
e70499 (16 pp.)
Abstract
Although significant N₂ fixation rates (NFRs) have been observed throughout mid-Atlantic coastal waters, studies have been limited in their temporal coverage, and the methods used to detect nitrogen fixers (diazotrophs) and their findings have varied. This study investigated NFRs and diazotroph communities in a dynamic coastal setting between Nags Head and Pea Island, North Carolina, USA, during a monthly time series from June 2019 to August 2020, and an August 2019 cruise. We observed movement of the Cape Hatteras Front and distinct NFRs and diazotroph communities in the Mid-Atlantic Bight, South-Atlantic Bight, Chesapeake Bay and Oregon Inlet plume waters, and mixing zones. The highest NFR (42.4 ± 3.0 nmol N L−¹ d−¹) coincided with the frontal mixing zone, where nifH of assayed targets was most abundant and the nifH community highly diverse. Observations revealed significant seasonal variability in the diazotroph community and NFRs (below detection to 26.1 ± 9.3 nmol N L−¹ d−¹), with higher NFRs in the late summer and early fall. Furthermore, our comparison of three diazotroph detection methods (nifH gene amplicon sequencing, nifH quantitative PCR, and microscopy) confirms a combined approach is needed to thoroughly survey the diazotroph community, and corroborates previous suggestions that Richelia is selected against by the classical nifH sequencing primers. This study advances our understanding of coastal N₂ fixation by documenting how water mass dynamics affect biogeochemical regimes and diazotroph communities. Our findings have implications for predicting how climate-induced changes in water mass characteristics may impact coastal diazotroph community composition and activity in this region.
Rights
© 2026 The Authors.
This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.
Data Availability
Article states: "Raw nifH sequence data were submitted to the NCBI Sequence Read Archive under accession number PRJNA1197003. All other data not publicly available are in FigShare repository: https://doi.org/10.6084/m9.figshare.30366301.v1."
Original Publication Citation
Crider, K. E., Selden, C. R., Powell, K., Tuo, S. H., Muglia, M., Taylor, P., Mulholland, M. R., & Chappell, P. D. (2026). Water mass dynamics drive nitrogen fixation rates and diazotroph community composition in the coastal ocean. Limnology and Oceanography, 71(10), Article e70499. https://doi.org/10.1002/lno.70499
Repository Citation
Crider, Katherine E.; Selden, Corday R.; Powell, Kimberly; Tuo, Sing-how; Muglia, Michael; Taylor, Patterson; Mulholland, Margaret R.; and Chappell, P. Dreux, "Water Mass Dynamics Drive Nitrogen Fixation Rates and Diazotroph Community Composition in the Coastal Region" (2026). OES Faculty Publications. 591.
https://digitalcommons.odu.edu/oeas_fac_pubs/591
Supporting Information
Included in
Biodiversity Commons, Biogeochemistry Commons, Ecology and Evolutionary Biology Commons, Oceanography Commons