text: Unlike denitrification, which removes reactive nitrogen from the system under gaseous form (as N or NO), dissimilatory nitrate reduction to ammonium conserves nitrogen as dissolved species within the system. Since DNRA takes nitrate and converts it into ammonium, it does not produce N or NO gases. Consequently, DNRA recycles nitrogen rather than causing gaseous-N loss, which leads to more sustainable primary production and nitrification.
  Within an ecosystem, denitrification and DNRA can occur simultaneously. Usually DNRA is about 15% of the total nitrate reduction rate, which includes both DNRA and denitrification. However, the relative importance of each process is influenced by environmental variables. For example, DNRA is found to be three to seven times higher in sediments under fish cages than nearby sediments due to the accumulation of organic carbon.
  Conditions where dissimilatory nitrate reduction to ammonium is favoured over denitrification in marine coastal ecosystems include the following:
  * High carbon loads and high sulfate reduction rates (e.g. areas of coastal or river runoff)
  * Unvegetated subtidal sediment 
  * Marshes with high temperatures and sulfate reduction rates (producing high levels of sulfides), e.g. mangroves 
  * High organic matter deposition (e.g. aquacultures)
  * Ecosystems where organic matter has a high C/N ratio
  * High electron donor (organic carbon) to acceptor (nitrate) ratio
  * High summer temperatures and low NO concentrations
  High sulfide concentration can inhibit the processes of nitrification and denitrification. Meanwhile, it can also enhance dissimilatory nitrate reduction to ammonium since high sulfide concentration provides more electron donors.
  Ecosystems where DNRA is dominant have less nitrogen loss, resulting in higher levels of preserved nitrogen in the system. Within sediments, the total dissimilatory nitrate reduction to ammonium rate is higher in spring and summer compared to autumn. Prokaryotes are the major contributors for DNRA during summer, while eukaryotes and prokaryotes contribute similarly to DNRA during spring and autumn.
  Potential benefits of using dissimilatory nitrate reduction to ammonium for individual organisms may include the following:
  * Detoxification of accumulated nitrite: if an enzyme uses nitrate as an electron acceptor and produces nitrite, it can result in high levels of intracellular nitrite concentrations that can be toxic to the cell. DNRA does not store nitrite within the cell, reducing the level of toxicity.
  * DNRA produces an electron sink that can be used for NADH re-oxidation into NAD: the need for having an electron sink is more apparent when the environment is nitrate-limited.