Cassondra L. Williams
Biography
Cassondra L. Williams, Ph.D., is an Associate Project Scientist in the Department of Ecology and Evolutionary Biology at the University of California, Irvine, a Research Scientist at the National Marine Mammal Foundation in San Diego, and a Research Associate in the Department of Biology at the University of San Diego. A scholar in the field of comparative physiology, Williams has spent over two decades studying oxygen transport and diving physiology in marine mammals, birds, and turtles. Her research focuses on understanding how elite diving animals manage oxygen stores during breath-hold dives and how they respond to environmental challenges and disturbances. Williams received a Ph.D. in Marine Biology from Scripps Institution of Oceanography, University of California, San Diego in 2011.
Williams has been awarded multiple research grants from the National Science Foundation, including as principal investigator on collaborative projects totaling over $2.5 million to develop continuous metabolite sensors and investigate oxygen transport mechanisms in diving mammals. She developed a near-infrared spectrophotometer to continuously measure muscle oxygen saturation in freely diving penguins, advancing the field of biologging techniques for studying organismal function in natural environments. Her work on muscle oxygen depletion patterns in diving emperor penguins received the 2010 Outstanding Paper Prize from the Journal of Experimental Biology and the 2011 Edward A. Frieman Prize for Excellence in Graduate Student Research from Scripps Institution of Oceanography.
Williams serves as Associate Editor for Animal Biotelemetry and as IACUC Chair at the National Marine Mammal Foundation. She has mentored numerous graduate and undergraduate students in comparative physiology research and has been active in science education outreach, serving as Program Chair and Steering Committee Member for the Expanding Your Horizons STEM conference for female students since 2010. Williams also holds a J.D. from the University of Southern California, having practiced law before transitioning to marine biology research.
Return to topEducation
- Ph.D. in Marine Biology, Scripps Institution of Oceanography, UCSD, 2011
- M.S. in Biology, Purdue University, 2004
- J.D., University of Southern California, 1994
- B.S. in Business Administration, University of Southern California, 1990
- B.A. in International Relations, University of Southern California, 1990
Distinctions
- NIH Postdoctoral Fellowship, Multidisciplinary Exercise Sciences Training Program, 2011-2013
- NIH Doctoral Fellowship, Training Program in Marine Biotechnology, 2006-2007
- Scholander Award finalist, American Physiological Society, 2012
- Caroline tum Suden Professional Opportunity Award, American Physiological Society, 2016
- Research Recognition Award, American Physiological Society, 2012
- Outstanding Paper Prize, Journal of Experimental Biology, 2010
- Edward A. Frieman Prize for Excellence in Graduate Student Research, Scripps Institution of Oceanography, 2011
- U.C. Regents Fellowship, 2005-2006
Areas of Expertise
- Comparative Diving Physiology
- Oxygen Store Management
- Cardiovascular Responses to Submersion
- Muscle Oxygen Depletion Patterns
- Biologging Instrumentation Development
- Anthropogenic Disturbance Effects
- Chelonian Cardiovascular Dynamics
Recent Publications
- Ponganis, P. J., Williams, C. L., “Blood pH, hemoglobin function and oxygen transport throughout the dive cycle of emperor penguins” (opens in new tab), Journal of Experimental Biology, vol. 228, no. 22, pp. jeb251044, 2025.
- Ponganis, P. J., Williams, C. L., Scadeng, M., “Respiratory anatomy and physiology in diving penguins” (opens in new tab), Philosophical Transactions of the Royal Society B Biological Sciences, vol. 380, no. 1920, pp. 20230422, 2025.
- Cooley, L. A., Hindle, A. G., Williams, C. L., Ponganis, P. J., Hannah, S. M., Klinck, H., McDonald, B. I., “Physiological effects of research handling on the northern elephant seal (Mirounga angustirostris)” (opens in new tab), Comparative Biochemistry and Physiology Part A Molecular and Integrative Physiology, vol. 299, pp. 111771, 2025.
- Ponganis, P. J., Williams, C. L., Kendall-Bar, J. M., “Blood oxygen transport and depletion in diving emperor penguins” (opens in new tab), Journal of Experimental Biology, vol. 227, no. 6, pp. jeb246832, 2024.
- Brown, C.V., McKnight, J.C., Bain, A.R., Tremblay, J.C., Patrician, A., McDonald, B.I., Williams, C.L., Hindle, A.G., Pallin, L.J., Costa, D.P., Dujic, Z., “Selected and shared hematological responses to apnea in elite human free divers and northern elephant seals (Mirounga angustirostris)” (opens in new tab), American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, vol. 327, no. 1, pp. R46-R53, 2024.
- Williams, C.L., Ponganis, P.J., “Oxygen stores and diving” (opens in new tab), Physiology of Marine Mammals: Adaptations to the Ocean, CRC Press, pp. 51-69, 2023.
- Williams, C.L., McDonald, G., Ponganis, P.J., Horning, M., Klinck, H., Costa, D., Hindle, A., “Reduced venous oxygen depletion in response to at-sea acoustic disturbance in diving northern elephant seals”, Physiology, vol. 38, no. S1, pp. 5794987, 2023. Presented at American Physiology Summit, Irvine, CA.
- Williams, C.L., Hindle, A.G., “Field physiology: Studying organismal function in the natural environment” (opens in new tab), Comprehensive Physiology, vol. 11, no. 3, pp. 1979-2015, 2021.
- Williams, C.L., Czapanskiy, M.F., John, J.S., St. Leger, J., Scadeng, M., Ponganis, P.J., “Cervical air sac oxygen profiles in diving emperor penguins: Parabronchial ventilation and the respiratory oxygen store” (opens in new tab), Journal of Experimental Biology, vol. 224, pp. jeb230219, 2021.
- Kendall-Bar, J., Kendall-Bar, N., Forbes, A.G., McDonald, G., Ponganis, P.J., Williams, C., Horning, M., Hindle, A., Klinck, H., Beltran, R.S., Friedlaender, A.S., “Visualizing Life in the Deep: A creative pipeline for data-driven animations to facilitate marine mammal research, outreach, and conservation” (opens in new tab), Proceedings 2021 IEEE Vis Arts Program Visap 2021, pp. 1-10, 2021.
- Kooyman, G.L., McDonald, B.M., Williams, C.L., Meir, J.U., Ponganis, P.J., “The aerobic dive limit: After forty years, still rarely measured but commonly used” (opens in new tab), Comparative Biochemistry and Physiology Part A Molecular and Integrative Physiology, vol. 252, pp. 110841, 2021.
- Kooyman, G.L., Goetz, K., Williams, C.L., Ponganis, P.J., Sato, K., Eckert, S., Horning, M., Thorson, P.T., Van Dam, R.P., “Crary bank: a deep foraging habitat for emperor penguins in the western Ross Sea” (opens in new tab), Polar Biology, vol. 43, pp. 801-811, 2020.
- Williams, C.L., Sato, K., Ponganis, P.J., “Activity not submergence explains diving heart rates of captive loggerhead turtles” (opens in new tab), Journal of Experimental Biology, vol. 222, pp. jeb200824, 2019.
- Ponganis, P.J., McDonald, B.I., Tift, M.S., Williams, C.L., “Heart rate regulation in diving sea lions: the vagus nerve rules” (opens in new tab), Journal of Experimental Biology, vol. 220, pp. 1372-1381, 2017.
- Williams, C.L., Hicks, J.W., “Continuous arterial PO₂ profiles in unrestrained, undisturbed aquatic turtles during routine behaviors” (opens in new tab), Journal of Experimental Biology, vol. 219, pp. 3616-3625, 2016.
Most Cited Publications
- Meir, J.U., Champagne, C.D., Costa, D.P., Williams, C.L., Ponganis, P.J., “Extreme hypoxemic tolerance and blood oxygen depletion in diving northern elephant seals” (opens in new tab), American Journal of Physiology - Regulatory, Integrative and Comparative Physiology, vol. 297, pp. R927-939, 2009.
- Wallace, B., Williams, C., Paladino, F., Morreale, S., Lindstrom, R., Spotila, J.R., “Bioenergetics and diving activity of internesting leatherback turtles (Dermochelys coriacea) at Parque Nacional Marino Las Baulas, Costa Rica” (opens in new tab), Journal of Experimental Biology, vol. 208, pp. 3873-3884, 2005.
- Ponganis, P.J., Meir, J.U., Williams, C.L., “In pursuit of Irving and Scholander: a review of oxygen store management in seals and penguins” (opens in new tab), Journal of Experimental Biology, vol. 214, pp. 3325-3339, 2011.
- Meir, J.U., Stockard, T.K., Williams, C.L., Ponganis, K.V., Ponganis, P.J., “Heart rate regulation and extreme bradycardia in diving emperor penguins” (opens in new tab), Journal of Experimental Biology, vol. 211, pp. 1169-1179, 2008.
- Ponganis, P.J., Stockard, T.K., Meir, J.U., Williams, C.L., Ponganis, K.V., van Dam, R.P., Howard, R., “Returning on empty: extreme blood O₂ depletion underlies dive capacity of emperor penguins” (opens in new tab), Journal of Experimental Biology, vol. 210, pp. 4279-4285, 2007.
- Williams, C.L., Meir, J.U., Ponganis, P.J., “What triggers the aerobic dive limit? Patterns of muscle oxygen depletion during dives of emperor penguins” (opens in new tab), Journal of Experimental Biology, vol. 214, pp. 1802-1812, 2011.
- Ponganis, P.J., Stockard, T.K., Meir, J.U., Williams, C.L., Ponganis, K.V., Howard, R., “O-2 store management in diving emperor penguins” (opens in new tab), Journal of Experimental Biology, vol. 212, pp. 217-224, 2009.
- Williams, C.L., Hagelin, J.C., Kooyman, G.L., “Hidden keys to survival: the type, density, pattern and functional role of emperor penguin body feathers” (opens in new tab), Proceedings of the Royal Society B Biological Sciences, vol. 282, pp. 20152033, 2015.
- Horning, M., Andrews, R.D., Williams, C.L., “Best practices recommendations for the use of external telemetry devices on pinnipeds” (opens in new tab), Animal Biotelemetry, vol. 7, pp. 20, 2019.
- Williams, C.L., Ponganis, P.J., “Diving physiology of marine mammals and birds: the development of biologging techniques” (opens in new tab), Philosophical Transactions of the Royal Society B Biological Sciences, vol. 376, no. 1830, pp. 20200211, 2021.
Contact Information
Email: cassondw@uci.edu
Phone: (949) 824-4858
Address: 5336 McGaugh Hall
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Last updated on 4/24/2026.