Pat Tester


Pat is a native of Oklahoma and long before she received an undergraduate education in biology and chemistry at California State University-Sonoma, she had decided to become an oceanographer. There were a few detours, one included a two-year stint as the supervisor of the central quality control laboratory for a winery in Asti, CA, before she entered graduate school to complete M.S. and Ph.D. degrees at the School of Oceanography, Oregon State University in Corvallis, Oregon. Her dissertation research on zooplankton was completed at the Duke University Marine Laboratory in Beaufort, where, in 1979 she joined the staff of the National Marine Fisheries Laboratory (now National Ocean Service, NOAA).

Life and Career

Pat began her marine science career in 1979 when she joined the staff of the National Oceanic and Atmospheric Administration (NOAA) Fisheries Laboratory in Beaufort, NC, USA where she worked on lower trophic food web interactions. Her focus shifted dramatically in the fall of 1987 when she recognized the onset of a massive Karenia brevis red tide bloom in North Carolina coastal waters. Pat rapidly organized a coordinated response by Federal, State and Academic partners. That effort kept the public fully informed of the threat and prevented contaminated shellfish from reaching the market. Following the red tide event, Pat reoriented her research and for the next 30 years concentrated on questions involving phytoplankton-zooplankton interactions and effects of toxic or harmful phytoplankton on marine food webs. To achieve those research goals, Pat developed and led a team of ecologists, oceanographers, molecular biologists and chemists who directed their efforts toward the ecology and physiology of toxic phytoplankton. More than 150 journal articles and book chapters document their success in detecting and quantifying harmful algae and tracing toxins in marine food webs. Pat was named to the National Organizing Committee on Harmful Algae in 2000 and to the International Organizing Committee 2006-2008 and 2012-2018. She served as the president of the International Society for the Study of Harmful Algae from 2004-2008 and was a keynote speaker at the first National HAB meeting in Mexico, the 10th Canadian National HAB Conference in 2007, and International Conference on Harmful Algae 2014 in Wellington, New Zealand. In addition to her work with harmful algae, Pat helped initiate the National Research Council postdoctoral program at the Beaufort Laboratory, sponsoring six associates, as well as serving as a science panel member of the North Pacific Research Board from 2002-2017. In 2013, Pat retired from NOAA but continues to work on the biology and ecology of harmful algae as a consultant to NOAA and UNESCO-IAEA, WHO and FAO. She established Ocean Tester, LLC in 2013 to provide opportunities for research partners and to facilitate marine research and education. In her free time, Pat enjoys traveling, hand spinning, weaving, swimming and watching birds in the tidal marsh surrounding her home in eastern North Carolina.

Research strategy and mentoring

For more than 30 years, her research efforts have centered on phytoplankton-zooplankton interactions and effects of toxic or harmful phytoplankton on the marine food web. Throughout her career, Pat’s work has focused on applied research with significant management applications. For example, her publications on the 1987 red tide demonstrated the utility of using real-time satellite imagery of coastal waters to follow HAB bloom development. That successful application of led to the formation of the NOAA COASTWATCH program, which currently provides remotely sensed data for coastal regions throughout the US, Alaska and Hawaii (  Pat also presented testimony to the US Small Business Administration on the losses suffered by NC watermen during the extended red tide bloom. As a result, the US Congress amended the definition of "disaster” thereby allowing the Small Business Administration to provide assistance to fishers when "customary fishing waters are closed due to red tides". Watermen from Maine to Florida have applied for assistance from the SBA seven times since the legislation was amended.

From the late 1980s to early 2000s Pat pursued pioneering work on Karenia brevis, demonstrating the low levels found throughout the Gulf of Mexico, detailing trophic transfer of brevetoxins into copepods, and most importantly how blooms initiate offshore and are hydrodynamically accumulated near the coast. The large chl a per cell database she developed   allowed conversion of satellite derived chl a data to cell estimates, which was crucial in developing an operational satellite-based monitoring system for tracking K. brevis blooms in the Gulf of Mexico. For the past 15 years, that system has provided early warning to coastal resident in the region and allowed coastal managers and businesses to better manage and mitigate the adverse environmental and human health associated with these blooms. More recently Pat used holographic methods to visually demonstrate how even relatively low levels of Karenia inhibit copepod feeding, helping explain why blooms cause the collapse of affected food chains. 

In the mid to late 1990s, Pat pursued an active research program on Pfiesteria and related species. Her team developed molecular methods used to document that Pfiesteria’s life cycle lacked any amoeboid stages capable of killing fish. Related fieldwork also demonstrated Pfiesteria was not present at high enough concentrations to kill fish or threaten human health, nor was it the cause of ulcerative lesions found on many fish. Dissemination of this information significantly reduced the exaggerated concern over Pfiesteria’s health effects, which caused people to avoid consuming seafood and visiting coastal communities. Regional economic losses prior to the release of authoritative information were significant, exceeding $100 million a year.

In the late 1990s and early 2000s, Pat recognized any significant progress toward and ability monitor and predict ciguatera fish poisoning CFP events would require a much greater understanding of the taxonomy, ecology and toxicity of the causative Gambierdiscus species. To address this knowledge gap, Pat collaborated with Dr. Maria Faust from the Smithsonian Institution to isolate and identify species and develop molecular detection methods in association with Dr. Mirielle Chinain. That work led to a complete revision of the genus in 2009 and demonstrated the utility of using molecular methods for identifying Gambierdiscus species. Since that time, Pat and her working group have documented the incidence of ciguatera poisoning throughout the Caribbean and developed an improved artificial substrate sampling method for quantifying cell abundance.  She also collaborated in developing species-specific molecular assays, mapping global species distributions, improving ciguatoxin detection methods, investigating micro-habitat preferences, estimating species-specific toxicities and determining species-specific growth requirements. These efforts allowed the completion of physiologically based models predicting where abundances of Caribbean Gambierdiscus species are likely to be highest and how individual species growth rates will response to climate change. This large body of work advanced our overall understanding of ciguatera causing dinoflagellates and how ciguatera risk can be better assessed. She and her international colleagues have advanced the issue of ciguatera poisoning being added to the UN Fisheries and Agriculture Organization-World Health Organization’s CODEX Alimentarius list to help protect the health of consumers through adoption of science-based food standards.

Perhaps Pat’s greatest legacy can be found in the countless students and colleagues she has supported and mentored over the years. She has always had a special place in her heart for students, who have greatly benefited from her mentorship. She has an unflaggingly optimistic view of the world and a unique way of proposing strategies that has allowed her to provide solutions to difficult research and professional questions raised by many in the field over the past three decades. Pat is a warm, generous and very approachable Senior Scientist. She is highly appreciated by trainees in workshops, courses, and Ph.D. students for her altruistic support. 

Pat has mentored: M. Black, G. Cervetto, H. Cohen, A. Dubois, J. Dyble, R. Feldman, M. Geesey, C. Guo, R. Hardison, C. Holland, J. Hong, W. Litaker, J. Matweyou, A. Nau, E. Örnólfsdóttir, S. Kibler, R. Waggett, M. Vandersea and S. Varnam

10 Key publications

Litaker, R. W., Holland, W.C., Hardison, D.R., Pisapia, F., Hess, P., Kibler, S.R., Tester, P.A. (2017). Ciguatoxicity of Gambierdiscus and Fukuyoa species from the Caribbean and Gulf of Mexico. PLoS ONE

Tester, P.A., Kibler, S.R., Holland, W.C., Usup, G., Vandersea, M.W., Leaw, C.P., Lim, P.T., Larsen, J., Mohammad-Noor, N., Faust, M.A., Litaker, R.W. (2014). Sampling harmful benthic dinoflagellates: Comparison of artificial and natural Substrate methods. Harmful Algae. 39:8–25.

Tester, P.A., Feldman, R.L., Nau, A.W., Kiber, S.R., Litaker, R.W. (2010). Ciguatera fish poisoning and sea surface temperatures in the Caribbean Sea and the West Indies. Toxicon 56(5):698-710. DOI: 10.1016/j.toxicon.2010.02.026

Litaker, R.W., Vandersea, M.W., Faust, M.A., Kibler, Chinain, M., Holmes, M.J., Holland, W., Tester, P.A. (2009). Taxonomy of Gambierdiscus including four new species, Gambierdiscus caribaeus, Gambierdiscus carolinianus, Gambierdiscus carpenteri and Gambierdiscus ruetzleri (Gonyaulacales, Dinophyceae). Phycologia 48(5):344-390. DOI: 10.2216/07-15.1

Stumpf, R.P. Culver, M.E., Tester, P.A., Tomlinson, M.C., Kirkpatrick, G.J., Pederson, B.A., Truby, E., Ransibrahmanakul, V.,  Soracco, M. (2003). Monitoring Karenia brevis blooms in the Gulf of Mexico using satellite ocean color imagery and other data. Harmful Algae 2(2):147-160. DOI: 10.1016/S1568-9883(02)00083-5

Tester, P.A., Turner, J.T., Shea, D. 2000. Vectorial transport of toxins from the dinoflagellate Gymnodinium breve through copepods to fish. Journal of Plankton Research 22(1): 47–6. DOI: 10.1093/plankt/22.1.47

Tester, P.A., Steidinger, K.A. (1997). Gymnodinium breve red tide blooms: Initiation, transport, and consequences of surface circulation. Limnology and Oceanography 42(5, part2): 1039-1051. DOI: 10.4319/lo.1997.42.5_part_2.1039

Turner, J.T., Tester, P.A. (1997). Toxic marine phytoplankton, zooplankton grazers, and pelagic food webs. Limnology and Oceanography 42(5,part_2): 1203-1214. DOI: 10.4319/lo.1997.42.5_part_2.1203

Tester, P.A., Geesey, M.E., Guo, C.Z., Paerl, H.W., Millie, D.F. (1995). Evaluating phytoplankton dynamics in the Newport River Estuary (North Carolina, USA) by HPLC-derived pigment profiles. Marine Ecology Progress Series124(1-3):237-245. DOI: 10.3354/meps124237

Tester, P.A., Stumpf, R.P., Vukovich, F.M., Fowler, P.K., Turner, J.T. (1991). An expatriate red tide bloom: Transport, distribution, and persistence. Limnology and Oceanography. 36(5):1053-1061. DOI: 10.4319/lo.1991.36.5.1053


Prepared Beatriz Reguera, Wayne Litaker, Ana Amorin and Marta Estrada, with a lot of help from Pat’s friends.