Anammox in Tidal Marsh Sediments: The Role of Salinity, Nitrogen Loading, and Marsh Vegetation

Abstract

Anammox bacteria are widespread in the marine environment, but studies of anammox in marshes and other wetlands are still scarce. In this study, the role of anammox in nitrogen removal from marsh sediments was surveyed in four vegetation types characteristic of New England marshes and in unvegetated tidal creeks. The sites spanned a salinity gradient from 0 to 20 psu. The impact of nitrogen loading on the role of anammox in marsh sediments was studied in a marsh fertilization experiment and in marshes with high nitrogen loading entering through ground water. In all locations, nitrogen removal through anammox was low compared to denitrification, with anammox accounting for less than 3% of the total N 2 production. The highest relative importance of anammox was found in the sediments of freshwater-dominated marshes, where anammox approached 3%, whereas anammox was of lesser importance in saline marsh sediments. Increased nitrogen loading, in the form of nitrate from natural or artificial sources, did not impact the relative importance of anammox, which remained low in all the nitrogen enriched locations (<1%).

Stark Contrast in Denitrification and Anammox across the Deep Norwegian Trench in the Skagerrak

“…Although the anammox reaction and its affiliated bacteria have now been reported across a spectrum of estuarine, coastal, and deep-water sediments (5,6,16,26), some sediments have proven negative for anammox (9,26,34,35). To date, however, any negative accounts in the literature have been confined to studies of the reaction in shallow coastal embayments and/or an estuary proper.…”

“…Since then its activity and affiliated bacteria have been documented in a wide variety of deep marine, coastal, and estuarine sediments, and simply documenting anammox in the environment is no longer novel (5)(6)(7). Some seasonal studies, however, have shown anammox activity to be either ephemeral or absent in some estuarine and marsh sediments, and its true regulatory mechanisms remain to be resolved (8)(9)(10)(11).…”

Ecosystem metabolism in salt marsh tidal creeks and ponds : applying triple oxygen isotopes and other gas tracers to novel environments

“…While it may be expected that most of the nutrient supply in the chambers is met by sediment recycling of ammonia, it is possible that nitrate directly or indirectly (through nitrogen cycle reprocessing; Koop-Jakobsen and Giblin 2009Giblin , 2010 contributes to nitrogen availability to support GPP in the sediment chambers. Further, the lack of clear nutrient driven differences in NCP (section 9.1) does not preclude a nutrient effect on GPP.…”

Spatial Variability in Nitrification Rates and Ammonia-Oxidizing Microbial Communities in the Agriculturally Impacted Elkhorn Slough Estuary, California

“…Nitrification rates were calculated as the production rate of unlabeled NO 3 Ϫ plus that considered to be directly coupled to denitrification by the rate of production of 29 N 2 and 30 N 2 (see below). We did not include explicit consideration of anaerobic ammonium oxidation (anammox), which has been shown to be less important than denitrification in estuarine sediments (26,46,47,58) and which was undetectable in previous slurry incubations of Elkhorn Slough sediments (61 N content of the effluent NH 4 ϩ was measured using the ammonium diffusion method (21), whereby NH 4 ϩ in approximately 100 ml of sample water is converted to NH 3 (by increasing the pH with MgO), which is then trapped on an acidified filter disk encased in a Teflon membrane. Filters are later combusted and analyzed for percent 15 N via conventional EA-IRMS analysis.…”