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James Ammerman

Adjunct Professor

Science Coordinator–USEPA Long Island Sound Study

New England Interstate Water Pollution Control Commission



- University of California, San Diego, La Jolla, CA (Scripps Institution of Oceanography)

Research Topics:

Aquatic microbial ecology and biogeochemistry; estuarine, coastal, and open ocean phosphorus cycling; coastal eutrophication and hypoxia; molecular biology of microbial phosphorus assimilation; instrument development and automation; academic leadership and administration; research administration.


  • Bio/Research


    In contrast to freshwater environments where phosphorus is usually limiting, nitrogen and iron are the first nutrients considered when evaluating marine or estuarine productivity. However, the significance of phosphorus as a limiting nutrient in certain marine and estuarine environments has been more widely demonstrated in recent years. This is particularly true in estuarine and coastal environments with high nitrogen loading. Viewed globally, phosphorus is increasingly considered a scarce resource, as phosphorus fertilizer cannot be industrially produced like ammonia, and is therefore mined in Florida and elsewhere. My research interests have long focused on phosphorus biogeochemistry and microbial phosphorus assimilation in marine and estuarine environments, producing several highly-cited studies demonstrating the importance of phosphorus limitation in both estuarine and river-dominated coastal environments, such as the Chesapeake Bay the Gulf of Mexico, as well as in the oligotrophic Sargasso Sea. Though several studies of mine and others had suggested phosphorus limitation of primary productivity on the Louisiana Shelf in the 1990s due to the high nitrogen loading, it was our 2006 paper in   Environmental Science and Technology  which first clearly established the significance of this phosphorus limitation and its importance to the formation of the annual summer Gulf of Mexico “dead zone”. In 2006 I gave an invited presentation of this data to the Hypoxia Advisory Panel of the EPA Science Advisory Board and this 2006 paper was cited throughout their 2007 volume   Hypoxia in the Northern Gulf of Mexico, An Update by the EPA Science Advisory Board. As a result of this report, the   2008 Gulf Hypoxia Action Plan  for the first time developed a numerical target for the reduction of riverine total phosphorus as well as total nitrogen, calling for a 45% reduction of both; however recent data suggests that both are actually increasing.

    Awards and Honors

    Director’s Award for Collaborative Integration (Program Manager, Life in Extreme Environments Team), National Science Foundation, 1997

    Fellow of the American Association for the Advancement of Science (AAAS) in Biological Sciences, 1996

    Lindeman Award, American Society of Limnology and Oceanography, 1986 (annual award given for outstanding aquatic science paper published by a young scientist; for Ammerman and Azam, 1985)

    Antarctic Service Medal, National Science Foundation, 1979

  • Publications


    Publications Since 2006


    Sylvan J.B, Dortch Q, Nelson D.M., Brown A.M., Morrison W., and Ammerman J.W. Phosphorus limits phytoplankton growth on the Louisiana shelf during hypoxia formation.   Environmental Science & Technology. 40: 7548-7553 10.1021/es061417t.


    Dyhrman, S.T., J.W. Ammerman, and B.A.S. Van Mooy. Microbes and the marine phosphorus cycle.   Oceanography Magazine. 20(2): 110-116.

    Sylvan J.B, Quigg A., Tozzi S., and Ammerman J.W. Eutrophication-induced phosphorus limitation in the Mississippi River Plume: Evidence from fast repetition rate fluorometry.   Limnology and Oceanography. 52(6): 2679-2685.

    Dagg, M.J., Ammerman, J.W, Amon, R.M.W., Gardner, W.S., Green, R.E., and Lohrenz, S.E. A review of water column processes influencing hypoxia in the northern Gulf of Mexico.   Estuaries and Coasts.   30(5): 735-752.

    Gaas, B.M. and J.W. Ammerman. Automated high resolution ectoenzyme measurements: instrument development and deployment in three trophic regimes.   Limnology and Oceanography: Methods.   5:463-473.


    Chichester, K.D., M. Sebastian, J.W. Ammerman, and C.L. Colyer. Enzymatic assay of marine bacterial phosphatases by capillary electrophoresis with laser-induced fluorescence detection.   Electrophoresis   29(18): 3810-3816.


    Sebastian, M. and J.W. Ammerman. The alkaline phosphatase PhoX is more widely distributed in marine bacteria than the classical PhoA.   ISME Journal   3(5): 563-572.

    S.A. Jaeger, G.P. Klinkhammer, B.M. Gaas, and J.W. Ammerman. Design, assessment, and use of the multiple-enzyme analyzer (MEA), a tool for in situ monitoring of marine microbial activity.   Limnology and Oceanography: Methods. 7: 716-729.

    Casey, John R., M.W. Lomas, V.K. Michelou, S.T. Dyhrman, E.D. Orchard, J.W. Ammerman, and J.B. Sylvan. Phytoplankton taxon-specific orthophosphate (Pi) and ATP utilization in the western subtropical North Atlantic.   Aquatic Microbial Ecology  58(1): 31-44.


    Lomas, M.W., A.L. Burke, D. A. Lomas, D.W. Bell, C. Shen, S.T. Dyhrman, and J.W. Ammerman. Sargasso Sea phosphorus biogeochemistry: an important role for dissolved organic phosphorus (DOP).   Biogeosciences   7(2): 695-710.

    Orchard, E. D., Ammerman, J.W., Lomas, M. W., and Dyhrman, S. T. Dissolved inorganic and organic phosphorus uptake in Trichodesmium and the microbial community: The importance of phosphorus ester in the Sargasso Sea.   Limnology and Oceanography  55: 1390-1399 DOI: 10.4319/lo.2010.55.3.1390.


    Quigg, A., J.B. Sylvan, A.B. Gustafson, T. R. Fisher, S. Tozzi, and J. W. Ammerman. Going west: role of phosphorus limitation in expanding the primary production across the Louisiana shelf.   Aquatic Geochemistry  DOI 10.1007/s10498-011-9134-3.

    J.B. Sylvan, A. Quigg, S. Tozzi, and J. W. Ammerman. Mapping phytoplankton community physiology on a river impacted continental shelf: testing a multifaceted approach.   Estuaries and Coasts. DOI 10.1007/s12237-011-9415-5.

    Sebastian M.; Ammerman J. W. Role of the phosphatase PhoX in the phosphorus metabolism of the marine bacterium   Ruegeria pomeroyi   DSS-3.   Environmental Microbiology   Reports 3:535-542 DOI: 10.1111/j.1758-2229.2011.00253.x.


    M.J. Harke, D.L. Berry, J.W. Ammerman, and C.J. Gobler. Molecular response of the bloom-forming cyanobacterium,   Microcystis aeruginosa, to phosphorus limitation.   Microbial Ecology  63:188-198 DOI 10.1007/s00248-011-9894-8.


    Orcutt, K.M., K. Gundersen, and J.W. Ammerman. Intense ectoenzyme activities associated with   Trichodesmium  colonies in the Sargasso Sea.   Marine Ecology Progress Series  478:101-113, doi 10.3354/meps10153

    Sylvan, J.B. and J. W. Ammerman. Seasonal distributions of organic nutrients on the Louisiana continental shelf and their implications for nutrient limitation and hypoxia formation.   Marine Chemistry  154:113-123.


    Sylvan, J.B. and J. W. Ammerman. Corrigendum to “Seasonal distributions of organic nutrients on the Louisiana continental shelf and their implications for nutrient limitation and hypoxia formation” [MARCHE: 154C (2013) 113–123].   Marine Chemistry   164:130.

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