AME 55:105-113 (2009)  -  DOI: https://doi.org/10.3354/ame01285

FEATURE ARTICLE
Widespread occurrence of the anammox reaction in estuarine sediments

Joanna C. Nicholls, Mark Trimmer*

School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, UK
*Corresponding author. Email:

ABSTRACT: We assayed sediment for the anammox reaction at 40 sites from 9 estuaries during the summer of 2004. The anammox reaction was detected at all sites with its potential contribution to the production of N2 (ra, %) ranging from <1 to 11%. Overall, a higher contribution from anammox was positively correlated with both the concentration of NO3 in the overlying water and the organic carbon content of the sediment. Whilst the organic carbon content of the sediment decreased towards the coast, its reactivity remained essentially constant (k = 0.6 y–1), which suggested that the amount of organic carbon rather than its reactivity or quality was more important. In addition, our large dataset enabled us to critically assess the 2 assays for measuring anammox (15NH4+ or 15NO3). While the 2 assays gave good agreement at ra > 3% (>2 nmol N2 ml–1 wet sediment for anammox after 24 h), below this, though still detectable, anammox was underestimated with 15NH4+. The decrease in the estimate for anammox with 15NH4+ relative to 15NO3 was partly explained by a decrease in the recovery of N2 gas, probably as a result of significant dissimilatory nitrate reduction to ammonium (DNRA) in some of the slurries. The potential interference from DNRA in the anammox assay, however, would be low, with the probability of anamox making 30N2 (A30N2) being about 1.4%. Our findings provide firm evidence that the anammox reaction is widespread in estuarine sediments.


KEY WORDS: Anammox · Estuary · Sediment · Organic carbon · Nitrate


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Cite this article as: Nicholls JC, Trimmer M (2009) Widespread occurrence of the anammox reaction in estuarine sediments. Aquat Microb Ecol 55:105-113. https://doi.org/10.3354/ame01285

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