Rachel E. Sipler

Affiliated Scholar

Department: Physical Sciences


Ph.D., Oceanography, Rutgers, the State University of New Jersey, New Brunswick, NJ, October 2009.

B.S., Biology, Salisbury University, Salisbury, MD, June 2003.

B.S., Environmental Science, University of Maryland, Eastern Shore, Princess Ann, MD, June 2003.

Research Interests

Phytoplankton ecology, nutrient biogeochemistry, dissolved organic matter (DOM) bioavailability and toxicity, harmful algal blooms, high-resolution mass spectrometry, impacts of climate or environmental change on phytoplankton and bacterial community composition and nutrient cycling 


Sipler, R.E. and D.A. Bronk. 2014. Dynamics of Marine Dissolved Organic Nitrogen. In: Hansell D.A. and Carlson, C.A. (Eds) Biogeochemistry of Marine Dissolved Organic Matter 2nd edition. Academic Press. pp.127-232.

Sipler, R.E., L.M. McGuinness, G. J. Kirkpatrick, L. J. Kerkhof, and O. M. Schofield. 2014. Bacteriocidal effects of brevetoxin on natural microbial communities. Harmful Algae. 38: 101-109.

Killberg-Thoreson, L., R.E. Sipler, C. A. Heil, M. Garrett, Q.N. Roberts, and D.A. Bronk. 2014. Nutrients released from decaying fish support microbial growth in the eastern Gulf of Mexico. Harmful Algae. 38: 40-49.

Bronk, D.A., L. Killberg-Thoreson, M. R. Mulholland, R. E. Sipler, Q. N. Roberts, P. W. Bernhardt, M. Garrett, J. M. O’Neil, C. A. Heil. 2014. Nitrogen uptake and regeneration (ammonium regeneration, nitrification and photoproduction) in waters of the west Florida shelf prone to blooms of Karenia brevis. Harmful Algae. 38: 50-62.

Sipler, R.E., S.P. Seitzinger, R.J. Lauck, L.M. McGuinness, G.J. Kirkpatrick, D.A. Bronk, C.A. Heil, and O.M. Schofield. 2013. Relationship between dissolved organic matter, bacterial community composition and rapid growth of toxic red-tide Karenia brevis. Mar. Ecol. Prog. Ser.483: 31-45.

Killberg-Thoreson, L., R.E. Sipler, and D.A. Bronk. 2013. Anthropogenic nutrient sources supplied to a Chesapeake Bay tributary support algal growth: a bioassay and high resolution mass spectrometry approach. Estuaries and Coasts. DOI: 10.1007/s12237-013-9604-5.

Osborne, D.M., D.C. Podgorski, Q.N. Roberts, D.A. Bronk, R.E. Sipler, D. Austin, W.T. Cooper. 2013. Characterization of Reactive and Refractory Dissolved Organic Nitrogen Compounds in a Stormwater Treatment Area by Atmospheric Pressure Photoionization Fourier Transform-Ion Cyclotron Resonance Mass Spectrometry. Rapid Communications in Mass Spectrometry. 28: 851-858.

Voß, M., D.A. Bronk, B. Deutsch, R. Purvaja, R. Ramesh T. Rixen, R.E. Sipler, and N. Wannicke. 2012. Treatise on estuarine and coastal science: Internal cycling of nitrogen and nitrogen transformations. (Eds) Wolanski, E.and D. McLusky. Elsevier.

Sipler, R. E. and S. P. Seitzinger. 2008. Use of electrospray ionization (ESI) mass spectrometry to investigate complex dissolved organic matter (DOM) and its potential applications in phytoplankton research. Harmful Algae. 8:182-187.

Fellowships and Grants

Active or Past

Collaborative Research: Synergistic effects of iron, carbon dioxide and temperature on the fate of nitrate: Implications for future changes in export production in the Southern Ocean.

  • Funded by the National Science Foundation, Office of Polar Programs, 9/14 to 8/15. $143,275, R. Sipler (PI) current

Effluent organic nitrogen produced within wastewater treatment plants

  • Funded by the Water Environment Research Federation with in-kind support from Hampton Roads Sanitation District, 2/12 to 9/15. $255,000 
  • Bronk, D. (PI) and R. Sipler (Co-PI) current

How Will Marine Food Webs in the Coastal Arctic Respond to Increased Runoff Associated With Permafrost Melt?

  •   Funded by US Fish and Wildlife Service, Arctic LCC, 6/12 to 8/12, $33,211, R. Sipler (PI), Bronk, D. (Co-PI), M. Frischer and J. Nejstgaard (Co-PIs, SkIO), and T. Sutton (Co-PI, UAlaska) past

Chemical characterization of EON as it passes through a WWTP

  •   Funded by Hampton Roads Sanitation District, 2010, $64,607 + student internship Sipler, R. (PI) and D. Bronk (Co-PI) past

R. Sipler has served or is serving as the substitute PI for the following grants awarded to D. Bronk, while Bronk serves at the National Science Foundation. 

Synergistic effects of iron, carbon dioxide and temperature on the fate of nitrate: Implications for future changes in export production in the Southern Ocean

  • Funded by NSF: Antarctic Ocean and Atmospheric Science, 9/11 to 8/15, Bronk part $476,668. Allen, A. (PI, JCVI), D. Hutchin (Co-PI, USC), and D. Bronk (Co-PI)

Determining rates of group-specific phytoplankton and bacterial uptake of inorganic and organic nitrogen by means of stable isotope probing

  • Funded by NSF: Biological Oceanography, 3/10 to 2/13, Bronk part  $377,744 Wawrik, B. (PI, UOklahoma) and D. Bronk (Co-PI)

Does competition for nitrogen between autotrophs and heterotrophs control carbon fluxes in the western coastal Arctic?

  • Funded by NSF: Office of Polar Programs, 9/09 to 8/12, Bronk part $390,827 Yager, P. (PI, UGA), M. Frischer (Co-PI, SkIO) and D. Bronk (Co-PI)