Molecular Evidence For Sediment Nitrogen Fixation In A Temperate New England Estuary

Details

• Journal Title:
  PeerJ
• Personal Author:
  Newell, Silvia E. ; Pritchard, Kaitlyn R. ; Foster, Sarah Q. ; Fulweiler, Robinson W.
• NOAA Program & Office:
  OAR (Oceanic and Atmospheric Research) ; Sea Grant
• Sea Grant Program:
  WHOI (Woods Hole Sea Grant) ; MIT (MIT Sea Grant)
• Description:
  Primary production in coastal waters is generally nitrogen (N) limited with denitrification outpacing nitrogen fixation (N2-fixation). However, recent work suggests that we have potentially underestimated the importance of heterotrophic sediment N2-fixation in marine ecosystems. We used clone libraries to examine transcript diversity of nifH (a gene associated with N2-fixation) in sediments at three sites in a temperate New England estuary (Waquoit Bay, Massachusetts, USA) and compared our results to net sediment N2 fluxes previously measured at these sites. We observed nifH expression at all sites, including a site heavily impacted by anthropogenic N. At this N impacted site, we also observed mean net sediment N2-fixation, linking the geochemical rate measurement with nifH expression. This same site also had the lowest diversity (non-parametric Shannon = 2.75). At the two other sites, we also detected nifH transcripts, however, the mean N2 flux indicated net denitrification. These results suggest that N2-fixation and denitrification co-occur in these sediments. Of the unique sequences in this study, 67% were most closely related to uncultured bacteria from various marine environments, 17% to Cluster III, 15% to Cluster I, and only 1% to Cluster II. These data add to the growing body of literature that sediment heterotrophic N2-fixation, even under high inorganic nitrogen concentrations, may be an important yet overlooked source of N in coastal systems.
• Keywords:
  Estuaries Sediments
• Source:
  PeerJ 4:e1615
• DOI:
  https://doi.org/10.7717/peerj.1615
• Sea Grant Document Number:
  WHOI-R-16-001
• Document Type:
  Journal Article
• Place as Subject:
  New England
• Rights Information:
  CC BY
• Compliance:
  Library
• Main Document Checksum:
  urn:sha256:e4f92d3227425ab25a38005f30c548680ccc18548d1a89256facef43c3acb028
• Download URL:
  https://repository.library.noaa.gov/view/noaa/40031/noaa_40031_DS1.pdf
• File Type:
  [PDF - 2.53 MB ]