Description: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Bernhard, A. E., Beltz, J., Giblin, A. E., & Roberts, B. J. Biogeography of ammonia oxidizers in New England and Gulf of Mexico salt marshes and the potential importance of comammox. ISME Communications, 1, (2021): 9, https://doi.org/10.1038./s43705-021-00008-0

Description: Few studies have focused on broad scale biogeographic patterns of ammonia oxidizers in coastal systems, yet understanding the processes that govern them is paramount to understanding the mechanisms that drive biodiversity, and ultimately impact ecosystem processes. Here we present a meta-analysis of 16 years of data of ammonia oxidizer abundance, diversity, and activity in New England (NE) salt marshes and 5 years of data from marshes in the Gulf of Mexico (GoM). Potential nitrification rates were more than 80x higher in GoM compared to NE marshes. However, nitrifier abundances varied between regions, with ammonia-oxidizing archaea (AOA) and comammox bacteria significantly greater in GoM, while ammonia-oxidizing bacteria (AOB) were more than 20x higher in NE than GoM. Total bacterial 16S rRNA genes were also significantly greater in GoM marshes. Correlation analyses of rates and abundance suggest that AOA and comammox are more important in GoM marshes, whereas AOB are more important in NE marshes. Furthermore, ratios of nitrifiers to total bacteria in NE were as much as 80x higher than in the GoM, suggesting differences in the relative importance of nitrifiers between these systems. Communities of AOA and AOB were also significantly different between the two regions, based on amoA sequences and DNA fingerprints (terminal restriction fragment length polymorphism). Differences in rates and abundances may be due to differences in salinity, temperature, and N loading between the regions, and suggest significantly different N cycling dynamics in GoM and NE marshes that are likely driven by strong environmental differences between the regions.

Description: This research was made possible by grants from The Gulf of Mexico Research Initiative to the Coastal Waters Consortium (CWC) to A.E.B., A.E.G., and B.J.R. Additional funding to A.E.B. came from the National Science Foundation awards MCB-0457183 and DEB-0814586. The funders had no role in the design, execution, or analyses of this project. Data are publicly available through the Gulf of Mexico Research Initiative Information & Data Cooperative (GRIIDC) at https://doi.org/10.7266/N7T43R0G (GoM gene abundance 2012), https://doi.org/10.7266/N7WH2MXZ (GoM AOA TRFLP 2012), N7RR1W6N (GoM AOB TRFLP 2012), https://doi.org/10.7266/N7X63JVT (GoM gene abundance 2013), https://doi.org/10.7266/N7SF2T4H (GoM AOB TRFLP 2013), https://doi.org/10.7266/N7NP22D5 (GoM AOA TRFLP 2013), https://doi.org/10.7266/N7D50JXK (GoM gene abundance 2014), https://doi.org/10.7266/N78C9T6Q (GoM AOB TRFLP 2014), https://doi.org/10.7266/N74M92HT (GoM AOA TRFLP 2014), https://doi.org/10.7266/N7319SXQ (GoM gene abundance 2015–2016), https://doi.org/10.7266/N7Z899FT (GoM AOB TRFLP 2015–2016), https://doi.org/10.7266/N7TH8JQ3 (GoM AOA TRFLP 2015–2016), https://doi.org/10.7266/N70Z715C (GoM 2012 nitrification rates and sediment characteristics), https://doi.org/10.7266/N7Z31WJF (GoM 2013–2014 nitrification rates and sediment characteristics), https://doi.org/10.7266/N7-0SVP-NN22 (GoM 2015–2016 nitrification rates and sediment characteristics), https://doi.org/10.7266/N7-MJPN-EQ50 (NE gene abundance, rates, and sediment chemistry), https://doi.org/10.7266/N7-QSRR-0A74 (NE AOB TRFLP), https://doi.org/10.7266/N7-4FSS-EK19 (NE AOA TRFLP). Sediment chemistry data from PIE marshes is available at https://pie-lter.ecosystems.mbl.edu/data.

Description: Journal of the American Chemical Society DOI: 10.1021/jacs.6b01619