William Cochlan


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Cochlan headshot
Adjunct Professor of Biology
Marine Microbial Ecology & Oceanography
(415) 338-3541


Research Interests

I am a biological oceanographer/marine microbial ecologist who addresses the fundamental question: "What environmental factors control phytoplankton growth, their nutrition, and distribution in the ocean?" More specifically, how do the multiple interactions of light, temperature, salinity, macro- and micro-nutrients, and ocean acidity affect the physiology of marine phytoplankton and bacteria, and hence determine their growth rates, biochemical content, production of toxins, and distribution patterns in the sea from coastal to oceanic environments.

My laboratory studies phytoplankton in unialgal cultures and natural assemblages during field studies ranging from polar to equatorial waters. Recently, much of our efforts have been directed towards the study of toxic microalgae that form Harmful Algal Blooms (HABs) both locally in San Francisco Bay, adjacent coastal waters, and the Pacific Northwest, including the Salish Sea. As part of these efforts we study how ocean acidification affects the growth and toxicity of HAB species that bloom along the West Coast, and how ocean acidification affects the nutritional content of coastal phytoplankton found in the upwelling regions of this productive region.

In addition to studying both harmful and benign phytoplankton, we are involved in research to generate biofuels from lipogenic phytoplankton. Our research efforts support the development and optimization of the commercial technology for this emerging industry.



Wingert, C.J., and W.P. Cochlan. 2021. Effects of ocean acidification on the growth, photosynthetic performance, and domoic acid production of the toxigenic diatom Pseudo-nitzschia australis from the California Current system. Harmful Algae (In press)

Edmiston, C.A., W.P Cochlan, C.E. Ikeda, and A.L. Chang. 2021. Impacts of a temperate to tropical voyage on the microalgal hull fouling community of an atypically-operated vessel. Mar. Pollut. Bull. 165: 112112. https://doi.org/10.1016/j.marpolbul.2021.112112

Wells, M.L., B. Karlson, A. Wulff, R. Kudela, V. Asnaghi, E. Berdalet, W. Cochlan, K. Davidson, M. De Rijcke, S. Dutkiewicz, G. Hallegraeff, K.J. Flynn, H. Paerl, C. Legrand, J. Silke, S. Suikkanen, P. Thompson, V. Trainer, and C. Trick. 2020. Future HAB science: Directions and challenges in a changing climate. Harmful Algae 91: 101632. https://doi.org/10.1016/j.hal.2019.101632

Trainer, V.L., S.K. Moore, G. Hallegraeff, R.M. Kudela, A. Clement, J.I. Mardones, and W.P. Cochlan. 2020. Pelagic harmful algal blooms and climate change: Lessons from nature’s experiments with extremes. Harmful Algae 91: 101591. https://doi.org/10.1016/j.hal.2019.03.009

Meyers, M.T., W.P. Cochlan, E.J. Carpenter, and WJ. Kimmerer. 2019. Effect of ocean acidification on the nutritional quality of marine phytoplankton for copepod reproduction. PLoS ONE 14(5): e0217047. https://doi.org/10.1371/journal.pone.0217047

Trick, C.G., V.L. Trainer, W.P. Cochlan, M.L. Wells, and B.F. Beall. 2018 The successional formation and release of domoic acid in a Pseudo-nitzschia bloom in the Juan de Fuca Eddy: A drifter study. Harmful Algae 79: 105-114. https://doi.org/10.1016/j.hal.2018.08.007

Radan, R.L., and W.P. Cochlan. 2018. Differential toxin response of Pseudo-nitzschia multiseries as a function of nitrogen speciation in batch and continuous cultures, and during a natural assemblage experiment. Harmful Algae 73: 12-29.

McCabe, R.M., B.M. Hickey, R.M. Kudela, K.A. Lefebvre, N.G. Adams, B.D. Bill, F.M.D. Gulland, R.E. Thomson, W.P. Cochlan, and V.L. Trainer. 2016. An unprecedented coastwide toxic algal bloom linked to anomalous ocean conditions.  Geophys. Res. Lett. 34: doi:10.1002/2016GL070023.

Mansfeldt, C.B., L.V. Richtery, B.A. Ahner, W.P. Cochlan, and R.E. Richardson. 2016. Use of de novo transcriptome libraries to characterize a novel oleaginous marine Chlorella species during the accumulation of triacylglycerols. PLOS ONE 11(2): e0147527.

Ikeda, C.E., W.P. Cochlan, C.M. Bronicheski, V.L. Trainer, and C.G. Trick. 2016. The effects of salinity on the cellular permeability and cytotoxicity of Heterosigma akashiwo. J. Phycology 52: 745-760.

Wells, M.L., V.L. Trainer, T.J. Smayda, B.S.O. Karlson, C.G. Trick, R.M., Kudela, A. Ishikawa, S. Bernard, A. Wulff, D.M. Anderson, and W.P. Cochlan. 2015. Harmful algal blooms and climate change: Learning from the past and present to forecast the future. Harmful Algae 49: 68-93.

Bartal, R., B. Shi, W.P. Cochlan, and E.J. Carpenter, 2015. A model system elucidating calcification functions in the prymnesiophyte Emiliania huxleyi reveals dependence of nitrate acquisition on coccoliths. Limnol. Oceanogr. 60: 149-158.

Bittar, T.B., L.R. Sassano, B.J. Wheeler, S.L. Brown, W.P. Cochlan and Z.I Johnson. 2013. Carbon allocation under light and nitrogen resource gradients in two model marine phytoplankton. J. Phycology 49: 523-535.

Auro, M.E., and W.P. Cochlan. 2013. Nitrogen utlization and toxin production by two diatoms of the Pseudo-nitzschia pseudodelicatissima complex: P. cuspidata and P. fryxelliana. J. Phycology DOI: 10.111/jpy.12033.

Trainer, V.L., S.S. Bates, N. Lundholm, A.E. Thessen, W.P. Cochlan, N.G. Adams, and C.G. Trick. 2012. Pseudo-nitzschia physiological ecology, phylogeny, toxicity, monitoring and impacts on ecosystem health. Harmful Algae 14: 271-300.

Kudela, R.M., S. Seeyave, and W.P. Cochlan. 2010. The role of nutrients in regulation and promotion of harmful algal blooms in upwelling systems. Progr. Oceanogr. 85: 122-135.

Trick, C.G., B. Bill, W.P. Cochlan, M.L. Wells, V.L. Trainer, and L.D. Pickell. 2010. Iron enrichment stimulates toxic diatom production in High Nitrate, Low Chlorophyll areas. Proc. Nat. Acad. Sci. 107: 5887-5892.

Kudo, I., Y. Noiri, W.P. Cochlan, K. Suzuki, T. Aramaki, T. Ono, and Y. Nojiri. 2009.Primary productivity, bacterial productivity and nitrogen uptake in response to iron enrichment assimilation during the SEEDS II. Deep-Sea Res. II 56: 2755-2766.

Pickell, L.D., M.L. Wells, C.G. Trick and W.P. Cochlan. 2009. A sea-going continuous culture system for investigating phytoplankton community response to macro- and micro-nutrient manipulations. Limnol. Oceanogr. Methods 7: 21-32.

Trainer, V.L., M.L. Wells, W.P. Cochlan, C.G. Trick, B.D. Bill, K.A. Baugh, B. F. Beall, J.Herndon, and N. Lundholm. 2009. An ecological study of a massive bloom of toxigenic Pseudo-nitzschia cuspidata off the Washington State coast. Limnol. Oceanogr. 54: 1461-1474.

Wells, M.L., C.G. Trick, W.P. Cochlan, and B. Beall. 2009. Persistence of iron limitation in the western subarctic Pacific SEEDS II mesoscale fertilization experiment. Deep-Sea Res. II 56: 2810-2821.

Cochlan, W.P. 2008. Nitrogen Uptake in the Southern Ocean. In: Nitrogen in the Marine Environment, 2nd Edition, D.G. Capone, D.A. Bronk, M.R. Mulholland, and E.J. Carpenter [Eds.]. Academic Press, Elsevier, pp. 569-596.

Cochlan, W.P., J. Herndon, and R.M. Kudela. 2008. Inorganic and organic nitrogen uptake by the toxigenic diatom Pseudo-nitzschia australis). Harmful Algae 8: 111-118.

Kudela, R.M., J.Q. Lane, and W.P. Cochlan. 2008. The potential role of anthropogenically derived nitrogen in the growth of harmful algae in California, USA. Harmful Algae 8: 103-110.

Herndon, J., and W.P. Cochlan. 2007. Nitrogen utilization by the raphidophyte Heterosigma akashiwo: growth and uptake kinetics in laboratory cultures. Harmful Algae 6: 260-270.

Coale, K.H., et al., (including W.P. Cochlan) 2004. Southern Ocean Iron Enrichment Experiment: Carbon Cycling in High- and Low-Si Waters. Science 304: 408-414.

Cochlan, W.P., and D.A. Bronk. 2003. Effects of ammonium on nitrate utilization in the Ross Sea: Implications for ƒ-ratio estimates. In: DiTullio, G.R, Dunbar, R.B. [Eds.], Biogeochemistry of the Ross Sea. AGU Antarctic Research Series 78: 159-178.

Cochlan, W.P., D.A. Bronk, and K.H. Coale. 2002. Trace metals and nitrogenous nutrition of Antarctic phytoplankton: experimental observations in the Ross Sea. Deep-Sea Res. II 49: 3365-3390.

Cochlan, W.P. 2001. The heterotrophic bacterial response during a mesoscale iron enrichment experiment (Iron Ex II) in the eastern equatorial Pacific Ocean. Limnol. Oceanogr. 46: 428-435.

Cochlan, W.P., and D.A. Bronk. 2001. Nitrogen uptake kinetics in the Ross Sea, Antarctica. Deep-Sea Res. II 48: 4127-4153.