People | David A. Hutchins

• B.S., Biology, Portland State University, 1987.
• M.S., Biology, Portland State University, 1989.
• Ph.D., Biology, University of California, Santa Cruz, 1994.

Current research interests in my lab include basic investigations into iron and nutrient limitation of marine phytoplankton growth, impacts of global change on ocean biology and biogeochemistry, as well as a more applied focus on harmful algal blooms in the Delmarva region. In general, our work involves forming hypotheses from carefully controlled laboratory investigations that are then tested in field experiments with natural plankton communities. Currently projects are underway in diverse marine ecosystems, ranging from local Delaware estuaries to the coastal upwelling regions of North and South America, as well as in the remote oceanic areas of the tropical Atlantic, North Pacific and the Southern Ocean. I am always interested in talking to bright, motivated potential graduate students or postdocs-feel free to email me if you are interested in our work!

Phytoplankton Iron Limitation

I have been working in this area since I was a graduate student, and this continues to be a major emphasis of my research. For instance, along with my collaborator Ken Bruland we have provided the first evidence for phytoplankton iron limitation in the coastal upwelling areas of California and Peru, and more recently in the Bering Sea. Perhaps our most widely recognized contribution to this field was the discovery that iron availability controls the Si:N and Si:C ratios of diatoms. This finding has now been confirmed by many researchers working all over the world, and has important implications for fields as diverse as algal physiology, carbon and nutrient biogeochemistry, global climatology, and paleoceanography.

My group has also pioneered the use of a unique new research tool, the shipboard continuous culture system, which has allowed us to carry out experiments examining iron effects on community structure and biogeochemistry that can be applied to questions (such as the effects of realistic, low-level iron supply rates) that cannot be addressed using traditional incubation methodology. We have now carried out shipboard nutrient and iron chemostat experiments in the Sargasso Sea, Peru, the Bering Sea, the North Atlantic, and several parts of the Southern Ocean, work which is now either published, submitted or being worked up for publication.

We are continuing to work in the iron limitation field with a new NSF Office of Polar Programs-supported project starting this year in the Ross Sea, Antarctica to examine how iron affects the balance between diatoms and Phaeocystis dominance in this region. Another exciting new development is the work my recent postdoc Karine Leblanc carried out using a new fluorescent probe, PDMPO, to quantify the effects of iron and zinc availability on silica deposition in diatom frustules at the subcellular level.

Harmful Algal Blooms (HAB's)

Another major research emphasis in my group is the study of harmful algal blooms (HABs). The Delaware Inland Bays are textbook examples of highly eutrophied estuaries, and consequently have been plagued with blooms of numerous species of nuisance and toxic algae. This unfortunate situation however makes our local estuaries the ideal natural laboratory for harmful algal bloom studies. Among our recent projects was participation in a regional ECOHAB Pfiesteria project, in which we along with our collaborators at CEOE helped to develop novel PCR methods for detecting and measuring Pfiesteria abundance. My graduate student Clint Hare discovered a native marine bacterium that inhibits the growth of Pfiesteria and all other dinoflagellates that we have examined, with no apparent ill effects on other phytoplankton groups. This work was recently published at Harmful Algae.

We have also done considerable work on the brown tide organism Aureococcus anophagefferens. Although not toxic to humans, this bloom forming alga has devastated estuarine ecosystems along parts of the Atlantic coast of the US. Among our most interesting findings during this project was the development by my student Linda Popels of a published quantitative PCR method to detect and enumerate the species with unprecedented sensitivity, down to levels as low as one cell per milliliter. Using this new method we have shown that the range of the organism is much greater than was previously recognized (Maine to Florida), that it is present in offshore waters (possibly providing a source of inoculum for estuarine blooms), and that it can be carried alive in both ship ballast tanks and recreational boat bilge water, with implications for anthropogenic transport and invasive species issues. My student Fran Pustizzi also published a paper examining the relationship between light and organic nitrogen availability in brown tide cultures, factors which are believed to be important for bloom establishment and maintenance.

Our latest HAB project is a collaboration with our CEOE colleagues Craig Cary and Kathy Coyne and Martina Doblin from ODU, and is supported by a current ECOHAB grant. We are now in the second year of a comprehensive examination of toxic raphidophyte blooms in our Inland Bays. These algae had never been reported from the East Coast of the US until 2000, when they suddenly began forming massive toxic blooms in our local estuaries. The fascinating thing about these blooms from the algal ecology point of view is that rather than being dominated by a single species as are most harmful blooms, they instead consist of a consortium of at least four related species (two Chattonella spp., Fibrocapsa sp., and Heterosigma sp.). This new project is trying to identify and understand the “raphidophyte niche” that has apparently recently opened for this entire group in our local waters.

Although still in the early stages, this project has made considerable progress already. We have now isolated these raphidophyte species in unialgal cultures, have completed a detailed comparison of nutrient, temperature, salinity and light effects on their growth, and have developed species-specific quantitative PCR probes to measure their abundance in mixed natural samples. Among the other aspects we are actively investigating include their vertical migration behavior using quantitative PCR (with a paper currently in press by my student Sara Handy), mortality through micro- and mesozooplankton grazing and possibly viruses (my student Elif Demir and collaborator Doblin), and recruitment from benthic resting cysts (with Cary and Coyne). Many of our results from this project were presented at the International HAB meeting in South Africa last fall and at the 3rd annual U.S. HAB Symposium in October, 2005 in Monterey, California.

• Yaohong Zhang, B.S. from the University of Quingdao, China. Yaohong is an expert on phytoplankton culturing and identification, and keeps the lab running for all of the rest of us. She is now working on understanding the nutrient requirements of the HAB alga Chattonella, which she isolated from the Inland Bays.
• Elif Demir, Ph.D. Oceanography student, January 2002 - present. Elif's project is supported by my ECOHAB funding. She is working on bacterial and viral controls of HAB growth, and on micrograzing control of toxic algal blooms in the Delaware Inland Bays. Elif has been a co-author on one paper. Ph.D. proposal defended in spring 2004.
• Yuanyuan Feng, MS Oceanography student, August 2004 - present. Yuanyuan is working on climate change impacts on phytoplankton communities, supported by my NSF funding. Yuanyuan is planning to bypass the Master's degree and become a Ph.D. student.
• Clinton Hare, Oceanography Ph.D. Student, April 2003- present. Clinton is supported by my NSF funding. He is working on developing shipboard continuous culture systems to assess limitation of phytoplankton growth by iron and nutrients and effects of climate change on algal community structure. One first author paper is published from this work, and Clint is a coauthor on another. Ph.D. proposal defended in fall 2004.
• Sara Handy, Ph.D. Student Oceanography, July, 2003 - present. Sara is working on molecular and physiological characterization of harmful algal blooms supported by my ECOHAB grant. One first author paper is in press. Master's bypass proposal defended May 14, 2004.
• Dr. Feixue Fu, September 2003 - present. Feixue is working on Trichodesmium, phosphorus biogeochemistry, harmful algal blooms, and climate change research. One first paper from this work has been published, another is in press, and a third has been submitted. She is also a co-author on a published Nature paper and an invited review chapter. She is supported by my NSF funding.
• Nathan Garcia, Ph.D Oceanography student, September 2006

I teach general oceanography courses and specialty courses in biological oceanography, phytoplankton biology and marine biogeochemistry.

Reprints or pdf files are available on request
First author papers by my students and postdocs are marked with an asterisk*

Papers in Press

*Demir, E., Coyne, K.J., Doblin, M.A., Handy, S.M. and Hutchins, D.A.. (In press). Microzooplankton grazing rates on Heterosigma akashiwo in the Delaware Inland Bays: A species-specific approach combining quantitative real-time PCR (QPCR) and dilution methods. Aquatic Microbial Ecology.

Hutchins, D.A. and Fu, F.-X. Linking the oceanic biogeochemistry of iron and phosphorus with the marine nitrogen cycle. (In press). In: Nitrogen in the Marine Environment, D. Capone, E. Carpenter, M. Mulholland and D. Bronk [Eds.] (Invited, refereed review chapter).

Tovar-Sanchez, A., Sañudo-Wilhelmy, S.A., Kustka, A.B., Augusti, S., Dachs, J., Hutchins, D.A. and Duarte, C.M. (In press). Impact of dust deposition and river discharges on trace metal composition of Trichodesmium spp. in the tropical and subtropical North Atlantic Ocean. Limnology and Oceanography.

Coyne, K.J., Hare, C.E., Popels, L.C., Hutchins, D.A. and Cary, S.C. (In press). Distribution of Pfiesteria piscicida cyst populations in sediments of the Delaware Inland Bays, USA. Harmful Algae. (invited submission to special issue on Pfiesteria, P. Gilbert, ed.).

Miao, A.J., Hutchins, D.A., Yin, I., Fu, F-X, Harrison, P.J. and Wang, W.-X. (In press). Macronutrient and iron limitation of phytoplankton growth in Hong Kong coastal waters. Marine Ecology Progress Series.

Published Papers

*Handy, S.M.,  Hutchins, D.A., Cary, S.C. and Coyne, K.J. 2006. Simultaneous enumeration of multiple raphidophyte species by multiprobing and multiplexing: capabilities and limitations. Limnology and Oceanography: Methods 4:193-204.

Frew, R.D., Hutchins, D.A., Nodder, S., Sañudo-Wilhelmy, S., Tovar-Sanchez, A., Leblanc, K., Hare, C.E. and Boyd, P.W. (2006). Particulate iron dynamics during FeCycle in subantarctic waters southeast of New Zealand. Global Biogeochemical Cycles, 20(1):GB1S93, doi:10.1029/2005GB002558.

*Fu, F.-X., Zhang, Y., Feng, Y. and Hutchins, D.A. (2006). Phosphate and ATP uptake and growth kinetics in axenic cultures of the cyanobacterium Synechococcus CCMP1334. European Journal of Phycology,41:15-28.

Zhang, Y., Fu, F.-X., Whereat, E., Coyne, K.J. and Hutchins, D. A. (2006). Bottom-up controls on a mixed-species HAB assemblage: A comparision of sympatric Chattonella subsalsa and Heterosigma akashiwo (Raphidophyceae) isolates from the Delaware Inland Bays, USA . Harmful Algae, 5:310-320.

*Handy, S.M., Coyne, K.J., Portune, K.J., Demir, E., Doblin, M.A., Hare, C.E., Cary, S.C. and Hutchins, D.A. (2005). Evaluating vertical migration behavior of harmful raphidophytes in the Delaware Inland Bays utilizing quantitative real-time PCR. Aquatic Microbial Ecology, 40:121-132.

McKay, R.M.L., Wilhelm, S.W., Hall, J., Hutchins, D.A., Mioni, C., Al-Rshaidat, M.M.D., Porta, D. and Boyd, P.W. (2005). Impact of phytoplankton on the biogeochemical cycling of iron in subantarctic waters southeast of New Zealand during FeCycle. Global Biogeochemical Cycles, 19(4):GB4S24.

Boyd, P.W., Law, C.L., Hutchins, D.A., Abraham, E., Crott, P.L., Ellwood, M., Frew, R.D., Hall, J., Handy, S., Hare, C., Higgins, J., Hill, P., Hunter, K.A., Leblanc, K., Maldonado, M.T., McKay, R.M., Mioni, C., Oliver, M., Pickmere, S., Safi, K., Sander, S., Sañudo-Wilhelmy, S.A., Smith, M., Strzepek, R., Tovar-Sanchez, A. and Wilhelm, S.W. (2005)   FeCycle - attempting an iron biogeochemical budget from a mesoscale SF6 tracer experiment in unperturbed low iron waters. Global Biogeochemical Cycles, 19(4):GB4S20.

Coyne, K.J., Handy, S.M., Demir, E., Whereat, E.B., Hutchins, D.A., Portune, K.J., Doblin, M.A. and Cary, S.C. (2005). Improved quantitative real-time PCR assays for enumeration of harmful algal species in field samples using an exogenous DNA reference standard. Limnology and Oceanography: Methods, 3:381-391.

Fu, F.-X., Zhang, Y., Leblanc, K., Sañudo-Wilhelmy, S.A. and Hutchins, D.A. (2005). The biological and biogeochemical consequences of phosphate scavenging onto phytoplankton cell surfaces. Limnology and Oceanography, 50:1459-1472.

*Leblanc, K. and Hutchins, D.A. (2005)  New applications of a biogenic silica deposition fluorophore in the study of oceanic diatoms. Limnology and Oceanography: Methods, 3:462-476 pdmpo images

• Dr. Karine Leblanc, November 2002-August 2005.
  Karine did a postdoc in my laboratory during which she worked on understanding the relationship between trace metal availability and silicification of diatoms using a new subcellular biochemical tracer method. She has two first author papers in press from this work, is currently preparing another, and also was a coauthor on several others. Karine was supported by a French Lavoisier Fellowship and my NSF funding. She is currently on the faculty of the University of Marseilles.
• Dr. Kate Achilles, Oceanography Ph.D. Degree defended September 27, 2004. (co-advised with Tom Church).
  Dissertation title: "The importance and bioavailability of iron to Trichodesmium." Kate's work has so far resulted in one first author paper with two more in preparation. She is now a postdoctoral researcher with Dr. John Zehr at University of California-Santa Cruz.
  Awards and Honors: Best Student Poster Award, ASLO Ocean Research Conference (2004); Best Student Paper, Oceanography Program (2004).
• Dr. Linda Popels, Oceanography Ph.D. Degree, October 2003.
  Dissertation title: "Detection, distribution and dark survival of the brown tide algae Aureococcus anophagefferens." Linda's Ph.D. work resulted in two first author papers and another submitted and three on which she was a coauthor. Presently Linda is employed as a postdoc with Dr. Mike McKay at Bowling Green University.
  Awards and Honors: NSF Graduate Research Traineeship Fellowship (1999-2001), Okie Fellowship (2001-2002), Delaware Sea Grant Student Award (2003), Frances Severance Award for Best Student Thesis and The Oceanography Program Award (2004).
• Clinton Hare, Oceanography Master's Degree, Spring 2003.
  Thesis defended March 18, 2003. Thesis title: "The bacteria community as a potential biological control of Pfiesteria piscicida." Clint has two first-author papers and has been a coauthor on five others. After receiving his MS, Clint elected to remain with my research group as a Ph.D. student. He should be finished in early 2006.
  Awards and Honors: Thomas J. Hinckle Award for Best Research Project in the Delaware Inland Bays (2003).
• Dr. Lexia Valdes Weaver, Marine Biosciences Ph.D. Degree, Spring 2003.
  Dissertation title: "Effects of changing molar ratios and concentrations of nitrogen and phosphorus in phytoplankton growth and community structure in the Delaware Inland Bays." Lexia is now a postdoctoral researcher with Dr. Hans Paerl at University of North Carolina.
  Awards and Honors: University Presidential Fellowship for Under-Represented Minorities (2000-2001), Thomas J. Hinckle Award for Best Research Project in the Delaware Island Bays (2000).
• Frances Pustizzi, Oceanography Master's Degree, 2002.
  Thesis defended on October 6, 2002. Thesis title: "The effects of nutrient and light interactions on the growth and photosynthesis of the brown tide organism Aureococcus anophagefferens." One first author paper was published from her thesis and she was a coauthor on another. Fran is now working as a high school science teacher in Oregon.
• Giselle Firme, Oceanography Master's Degree, 2001.
  MS completed, November 2001. Thesis title "Mapping the temporal and spatial variability in phytoplankton Fe limitation in the California upwelling region: Implication for biological Si, N and C stoichiometry." One first author paper has been published from this work and she was coauthor on another. Giselle worked at CORE in Washington D.C. after graduation and is currently the Director of Ponto 3 Constructora in Brazil.
  Awards and Honors: Knauss Marine Policy Fellowship (2001).
• Richard Weaver, Oceanography Master's Degree, 2001.
  Thesis title "Utilization of model ligand/55Fe complexes by marine plankton in natural communities and laboratory cultures." Rich published one first author paper and was listed as a coauthor on three others. He is now working as a laboratory technician with Dr. Hans Paerl, University of North Carolina.
• Mark A. Schmidt, Oceanography Master's Degree, September 1998.
  MS completed, Fall 1998. Thesis title: "Iron and carbon uptake in marine plankton." Mark's thesis resulted in two first-author publications and one coauthored publication. Currently Mark is flying jets as an officer in the Air Force.
  Awards and Honors: Oceanography Program Fellowship (1998-1999).

• Associate Editor, Journal of Geophysical Research, Oceans, November 2000 - present.
• Invited Member, ASLO 2006 Summer Meeting Organizing Committee,  June 2005 - present.
• Invited Member, SCOR and IGBP Integrated Marine Biogeochemical and Ecosystem Research (IMBER) Scientific Steering Committee, June 1, 2004 - present.
• Invited Member, U.S. IMBER/SOLAS (Surface Ocean Lower Atmosphere Study) Coordinating Committee, September, 2004-present.
• Invited Member, NSF Ocean Carbon Cycle Research (OCCR) Planning Committee in the Division of Ocean Sciences, 2001-present.
• Invited Participant, Ecological Determinants of Oceanic Carbon Cycling (EDOCC) Workshop, Timberline Lodge, Oregon, March 12-16, 2000.
• Invited Visiting Scholar, Atmospheric, Marine and Coastal Environment Program, School of Science, Hong Kong University of Science and Technology, Hong Kong. Course taught: “Marine Biogeochemistry”, June 4-30, 2004. Hosts Dr. Wen Wang and Prof. Paul Harrison.
• Invited Visiting Scientist, National Institute of Water and Atmosphere and Department of Chemical and Physical Oceanography, University of Otago, Dunedin, New Zealand. January 1, 2002-June 1, 2003. Host Dr. Phillip Boyd.
• Invited Lecturer, University of Concepcion, Dichato, Chile. Course taught: "First Austral Summer Institute - Special Topics in Chemical Oceanography", January 2001. Host Dr. S. Pantoja.
• Invited Mentor, DIALOG panel on proposal writing for new Ph.D. graduates, Spring 2004 Ocean Research Conference, Honolulu HI.

Current Grants

“A new HAB invader in the Inland Bays: Initial isolation and characterization of a low-salinity raphidophyte species unknown to science.”  D.A. Hutchins and K.J. Coyne. Center for the Inland Bays. October 1, 2005.

“Collaborative research: US/EC Collaboration on Potential Climate Change Impacts on Algal Community Structure and Biogeochemistry During the North Atlantic Spring Bloom.”  D.A. Hutchins. NSF Biological Oceanography. November 1, 2004 - October 31, 2007. NASB Data Files

“Collaborative research: Interactive effects of iron, light, and CO2 on phytoplankton community dynamics in the Ross Sea.”  D.A. Hutchins. NSF Office of Polar Programs. February 1, 2005 - January 31, 2008.

“Investigation of toxic Rhaphidophyte population dynamics using molecular and physiological tools.”  D.A. Hutchins, K. Coyne and C. Cary. EPA ECOHAB, October 1, 2003-September 30, 2006.

Recent Research Cruises

• North Atlantic Bloom Cruise. Fort Pierce, Florida to Reykjavik, Iceland . D. Hutchins, Chief Scientist. May 22- July 7, 2005. On this cruise, we collaborated with a group of researchers from the US, Canada and Germany to examine how rising global temperatures and CO2 may affect the future biology and biogeochemistry of the North Atlantic spring bloom, one of the most dramatic annual biological events in the world ocean.
• Bering Sea Cruise. Dutch Harbor, Alaska to Dutch Harbor. K. Bruland, Chief Scientist. August - September, 2003. D. Hutchins and research group participating. We carried out experiments to simulate the temperature and CO2 conditions expected in this area by the year 2100 and recorded the response of the plankton community and nutrient cycles. We also carried out experiments to determine the role of iron and other trace metals in limiting algal growth in this region.
• February 2003 Subantarctic. FeCycle Cruise. The cruise was on the Kiwi Research Vessel Tangaroa, and was an international effort by scientists from New Zealand, Australia, Europe and the US to study the in situ cycling of iron in an SF6-labeled patch of water, but without any addition of iron.
• Equatorial Pacific/Peru. Upwelling cruise. San Diego, CA to Arica, Chile, K. Bruland (U.C. Santa Cruz), Chief Scientist, D. Hutchins, Co-chief Scientist, August 21-September 28, 2000.
• Mid-Atlantic Bight Cruise. Lewes to Lewes, R.V. Cape Henlopen, D. Hutchins, Chief Scientist, September 28- October 3, 1998
• Sargasso Sea Cruise. Lewes-Bermuda-Lewes, R.V. Cape Henlopen, S. Wilhelm, Chief Scientist D. Hutchins, Co-chief Scientist, May 26 - June 16, 2000.
• California Upwelling Cruise. Moss Landing CA to Moss Landing CA, R.V. Pt. Sur, D. Hutchins, Chief Scientist, June 3-16, 1999.
• Sargasso Sea Cruise. Lewes-Bermuda-Lewes, R.V. Cape Henlopen, D. Hutchins, Chief Scientist, May 3-24, 1998.
• Subantarctic Zone Cruise. Hobart Tasmania - Hobart Tasmania, R.V. Aurora Australis, T. Trull (CSIRO, Tasmania), Chief Scientist, March 3-April 5, 1998, D. Hutchins participant.
• Delaware Bay and Shelf Waters Cruise. Lewes to Lewes, R.V. Cape Henlopen, J. Sharp, Chief Scientist, January 1998. M. Schmidt participant.
• N.E. Pacific Station P Cruise. Institute of Ocean Sciences, Victoria, B.C., Canada to Victoria. B.C., R.V. John P. Tully, C.S. Wong (I.O.S., Victoria), Chief Scientist, August- September 1997. M. Schmidt participant.
• Delaware Bay and Shelf Waters Cruise. Lewes to Lewes, R.V. Cape Henlopen, D. Kirchman, Chief Scientist, September 1997. D. Hutchins and research group participated.
• West Coast Upwelling Cruise. Moss Landing, CA - Victoria, B.C., R.V. Pt Sur, K. Bruland, Chief Scientist, June-July 1997. D. Hutchins participant.
• Delaware Bay Cruise. Lewes to Lewes, R.V. Cape Henlopen J. Sharp, Chief Scientist, April 10-11, 1997. D. Hutchins and research group participated.
• Mid-Atlantic Bight Cruise. Lewes to Lewes, R.V. Cape Henlopen G. Luther, Chief Scientist, October 1996, D. Hutchins and M. Schmidt participated.