Denitrification as the dominant nitrogen loss process in the Arabian Sea Export

@article{citeulike:5709842, abstract = {Primary production in over half of the world's oceans is limited by fixed nitrogen availability. The main loss term from the fixed nitrogen inventory is the production of dinitrogen gas (N2) by heterotrophic denitrification or the more recently discovered autotrophic process, anaerobic ammonia oxidation (anammox). Oceanic oxygen minimum zones (OMZ) are responsible for about 35\% of oceanic N2 production and up to half of that occurs in the Arabian Sea1. Although denitrification was long thought to be the only loss term, it has recently been argued that anammox alone is responsible for fixed nitrogen loss in the OMZs2, 3, 4. Here we measure denitrification and anammox rates and quantify the abundance of denitrifying and anammox bacteria in the OMZ regions of the Eastern Tropical South Pacific and the Arabian Sea. We find that denitrification rather than anammox dominates the N2 loss term in the Arabian Sea, the largest and most intense OMZ in the world ocean. In seven of eight experiments in the Arabian Sea denitrification is responsible for 87–99\% of the total N2 production. The dominance of denitrification is reproducible using two independent isotope incubation methods. In contrast, anammox is dominant in the Eastern Tropical South Pacific OMZ, as detected using one of the isotope incubation methods, as previously reported3, 5. The abundance of denitrifying bacteria always exceeded that of anammox bacteria by up to 7- and 19-fold in the Eastern Tropical South Pacific and Arabian Sea, respectively. Geographic and temporal variability in carbon supply may be responsible for the different contributions of denitrification and anammox in these two OMZs. The large contribution of denitrification to N2 loss in the Arabian Sea indicates the global significance of denitrification to the oceanic nitrogen budget}, author = {Ward, B. B. and Devol, A. H. and Rich, J. J. and Chang, B. X. and Bulow, S. E. and Naik, Hema and Pratihary, Anil and Jayakumar, A.}, citeulike-article-id = {5709842}, citeulike-linkout-0 = {http://dx.doi.org/10.1038/nature08276}, citeulike-linkout-1 = {http://dx.doi.org/10.1038/nature08276}, day = {3}, doi = {10.1038/nature08276}, issn = {0028-0836}, journal = {Nature}, keywords = {15n, anammox, denitrification, marine, real\_time\_pcr}, month = {September}, number = {7260}, pages = {78--81}, posted-at = {2009-09-08 10:33:48}, priority = {2}, publisher = {Macmillan Publishers Limited. All rights reserved}, title = {Denitrification as the dominant nitrogen loss process in the Arabian Sea}, url = {http://dx.doi.org/10.1038/nature08276}, volume = {461}, year = {2009} }

TY - JOUR ID - citeulike:5709842 L3 - citeulike-article-id:5709842 N2 - Primary production in over half of the world's oceans is limited by fixed nitrogen availability. The main loss term from the fixed nitrogen inventory is the production of dinitrogen gas (N2) by heterotrophic denitrification or the more recently discovered autotrophic process, anaerobic ammonia oxidation (anammox). Oceanic oxygen minimum zones (OMZ) are responsible for about 35% of oceanic N2 production and up to half of that occurs in the Arabian Sea1. Although denitrification was long thought to be the only loss term, it has recently been argued that anammox alone is responsible for fixed nitrogen loss in the OMZs2, 3, 4. Here we measure denitrification and anammox rates and quantify the abundance of denitrifying and anammox bacteria in the OMZ regions of the Eastern Tropical South Pacific and the Arabian Sea. We find that denitrification rather than anammox dominates the N2 loss term in the Arabian Sea, the largest and most intense OMZ in the world ocean. In seven of eight experiments in the Arabian Sea denitrification is responsible for 87–99% of the total N2 production. The dominance of denitrification is reproducible using two independent isotope incubation methods. In contrast, anammox is dominant in the Eastern Tropical South Pacific OMZ, as detected using one of the isotope incubation methods, as previously reported3, 5. The abundance of denitrifying bacteria always exceeded that of anammox bacteria by up to 7- and 19-fold in the Eastern Tropical South Pacific and Arabian Sea, respectively. Geographic and temporal variability in carbon supply may be responsible for the different contributions of denitrification and anammox in these two OMZs. The large contribution of denitrification to N2 loss in the Arabian Sea indicates the global significance of denitrification to the oceanic nitrogen budget IS - 7260 JF - Nature SN - 0028-0836 EP - 81 TI - Denitrification as the dominant nitrogen loss process in the Arabian Sea PB - Macmillan Publishers Limited. All rights reserved VL - 461 SP - 78 KW - 15n KW - anammox KW - denitrification KW - marine KW - real_time_pcr AU - Ward, BB AU - Devol, AH AU - Rich, JJ AU - Chang, BX AU - Bulow, SE AU - Naik, Hema AU - Pratihary, Anil AU - Jayakumar, A PY - 2009/09/03/ UR - http://dx.doi.org/10.1038/nature08276 ER -