AME 48:197-205 (2007)  -  doi:10.3354/ame048197

ABSTRACT: Anaerobic ammonium oxidation (anammox) and denitrification were measured in the open sea and coastal accumulation basins of the Gulf of Finland. The different methods used gave conflicting results on the importance of the anammox process in the sediments. Anammox generally contributed less than 20% to the total N₂ production, and no anammox was found in a shallow inner estuary basin. However, the discovery of the anammox process in the open sea sediments challenges the denitrification measurements made in the area, as the coexistence of anammox and denitrification compromises the central assumptions behind the method used in denitrification measurements and causes overestimates of the N₂ production. The high ¹⁵NO₃^– incubation concentration used in Baltic Sea denitrification measurements exacerbates this overestimation, which is likely to have been substantial.

KEY WORDS: Denitrification · Anaerobic ammonium oxidation · Anammox · Nitrogen cycling · Baltic Sea