Richard Dugdale


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Dugdale headshot
Adjunct Professor of Biology
Biological Oceanography and Biogeochemical Cycling
(415) 338-3518


Research Interests

I am a biological oceanographer specializing in biogeochemistry and modeling, and studying the interaction of phytoplankton, nutrients (primarily nitrogen and silicon), and CO2. My current research is focused on the causes of low productivity in the San Francisco Estuary/Delta ecosystem and links to anthropogenic inputs of ammonium. Our lab measures nutrient and chlorophyll, with nitrogen and carbon uptake by phytoplankton that are incorporated into models to predict where and when high phytoplankton levels (blooms) can be expected. We contribute to the development of the Bay coupled circulation and biogeochemical model, SCHISM/CoSiNE. We also study the productivity of the Gulf of the Farallones and its links to San Francisco Bay outflow. Another current focus is on the role of the California Undercurrent in linking and providing nutrients to the upwelling centers and possible effects of climate change on the undercurrent nutrients. For context, I pioneered the use of the stable isotope 15N as a tracer in aquatic studies that enabled primary production by phytoplankton to be separated into production based on the input of "new" nutrients or on regenerated nutrients, and the concept of new production, now a basic paradigm of biological oceanography that allows the estimate of primary production available for export up the food chain or downward to the deep sea and sediments. Most of my research has centered on coastal and equatorial upwelling ecosystems.  I constructed a silicate pump model linking silicate with nitrogen cycling that addressed the question "why isn't the equator greener?" and provided an alternative to the Fe hypothesis. Our silicate-limited productivity model has been incorporated into a general circulation model for the Pacific Basin, California coast and San Francisco Bay system.

Selected Papers

Dugdale, R.C. 2018. A biogeochemical oceanographer at sea: my life with nitrogen and a nod to silica. Annual Reviews in Marine Science 10: 1-18

Dugdale, R.C., F.P. Wilkerson, A.E. Parker. 2016. The effect of clam grazing on phytoplankton spring blooms in the low-salinity zone of San Francisco Estuary: a modelling approach. Ecological Modelling 340: 1-16.

Wilkerson, F.P. and R.C. Dugdale. 2016. The ammonium paradox of a high nutrient low chlorophyll estuary. In: Aquatic Microbial Ecology and Biogeochemistry: A Dual Perspective” (P.M. Glibert and T.M. Kana (eds), Springer, pp. 117-126.

Glibert, P.M., F.P. Wilkerson, R.C. Dugdale, J. A. Raven, C. Dupont, P.R. Leavitt, A.E. Parker, J.M. Burkholder, T.M. Kana. 2016. Pluses and minuses of ammonium and nitrate uptake and assimilation by phytoplankton and implications for productivity and community composition, with emphasis on nitrogen-enriched conditions. Limnology and Oceanography 61: 165-197.

Wilkerson, F.P., R.C. Dugdale, A.E. Parker, S.B. Blaser, A. Pimenta. 2015. Nutrient uptake and primary productivity in an urban estuary: using rate measurements to evaluate phytoplankton response to different hydrological and nutrient conditions. Aquatic Ecology 49(2): 211-233.

Lee, J., A.E. Parker, F.P. Wilkerson, R.C. Dugdale. 2015. Kinetics and inhibition of nitrogen uptake in Microcystis aeruginosa: results from cultures and field assemblages in the San Francisco Bay Delta, CA. Harmful Algae 47: 126-140.

Glibert, P.M., F.P. Wilkerson, R. C. Dugdale, A. E. Parker, J. Alexander, S. Blaser, S. Murasko. 2014. Phytoplankton communities from San Francisco Bay Delta respond differently to oxidized and reduced nitrogen substrates- even under conditions that would otherwise suggest nitrogen sufficiency. Frontiers in Marine Science. doi: 10.3389/fmars.2014.00017

Glibert P.M., R.C. Dugdale, F.P. Wilkerson, A.E. Parker, J.A. Alexander, E.A. Antell, S. Blaser, A. Johnson, J Lee, T. Lee, S. Murasko, S. Strong 2014. Major – but rare – spring blooms in 2014 in San Francisco Bay Delta, California, a result of the long-term drought, increased residence time, and altered nutrient loads and forms. Journal of Experimental Marine Biology and Ecology 460: 8–18.

Dugdale, R.C., F.P. Wilkerson, and A.E. Parker, 2013. A biogeochemical model of phytoplankton productivity in an urban estuary: the importance of ammonium and freshwater flow. Ecological Modeling 263: 291-307.

Buck, C., F.P. Wilkerson, A.E. Parker, R.C. Dugdale. 2013. The influence of coastal nutrients on phytoplankton productivity in a shallow low inlet estuary, Drakes Estero, California (USA). Estuaries and Coasts 37: 847-863. 10.1007/s12237-013-9737-6

Dugdale, R.C., F.P. Wilkerson, A.E. Parker, A. Marchi, and K. Taberski. 2012 River flow and ammonium discharge determine spring phytoplankton blooms in an urbanized estuary. Estuarine, Coastal and Shelf Science 115: 187-199

Parker, A.E., V.E. Hogue, F.P. Wilkerson and R.C. Dugdale. 2012 The effect of inorganic speciation on primary production in the San Francisco Estuary. Estuarine, Coastal and Shelf Science 104: 91-101.

Parker, A.E., R. C. Dugdale, F.P. Wilkerson. 2012. Elevated ammonium concentrations from wastewater discharge depress primary productivity in the Sacramento River and the Northern San Francisco Estuary. Marine Pollution Bulletin 64: 574-586

Dugdale, R, F. Chai, R. Feely, C. Measures, A. Parker, F. Wilkerson. 2011. The regulation of equatorial Pacific new production and pCO2 by silicate-limited diatoms, Deep-Sea Research II 58: 477-492. doi:10.1016/j.dsr2.2010.08.008.

Dugdale, R.C., F.P. Wilkerson, V.E. Hogue and A. Marchi. 2007. The role of ammonium and nitrate in spring bloom development in San Francisco Bay. Estuarine, Coastal and Shelf Science 73: 17-29.

Dugdale, R.C., F. P. Wilkerson, F.Chai, R. Feely. 2007. Size fractionated nitrogen uptake measurements in the equatorial Pacific and confirmation of the low Si-high nitrate low chorophyll condition. Global Biogochemical Cycles, 21, No 2 GB2005 doi:10.1029/2006GB002722.

Dugdale, R.C., F.P. Wilkerson, V.E. Hogue and A. Marchi. 2007. The role of ammonium and nitrate in spring bloom development in San Francisco Bay. Estuarine, Coastal and Shelf Science73: 17-29.

Chai, F., M.-S. Jiang, Y. Chao, R. C. Dugdale,F. Chavez, R. T. Barber. 2007. Modeling responses of diatom productivity and biogenic silica export to iron enrichment in the equatorial Pacific Ocean. Global Biogeochemical Cycles, 21, GB3S90, doi:10.1029/2006GB002804

Dugdale, R.C., F.P. Wilkerson, A.Marchi and V.Hogue. 2006. Nutrient controls on new production in the Bodega Bay, California, coastal upwelling plume. Deep-Sea Research II 53: 3049-3062.

Wilkerson, F.P., R.C. Dugdale, V.E. Hogue and A. Marchi. 2006. Phytoplankton blooms and nitrogen productivity in San Francisco estuary. Estuaries and Coasts 29: 401-416