Frances P. Wilkerson

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Diatoms are unicellular algae with plastids acquired by secondary endosymbiosis. They are responsible for approximately 20% of global carbon fixation. We report the 34 million-base pair draft nuclear genome of the marine diatom Thalassiosira pseudonana and its 129 thousand-base pair plastid and 44 thousand-base pair mitochondrial genomes. Sequence and(More)
The substantial inventory of nitrate (NO3) in San Francisco Bay (SFB) is unavailable to the resident phytoplankton most of the year due to the presence of ammonium (NH4) at inhibitory concentrations that prevents NO3 uptake. Low annual primary productivity in this turbid estuary is generally attributed to the poor irradiance conditions. However, this may(More)
A one-dimensional ecosystem model was developed for the equatorial Pacific upwelling system, and the model was used to study nitrogen and silicon cycle in the equatorial Pacific. The ecosystem model consisted of 10 components (nitrate, silicate, ammonium, small phytoplankton, diatom, microand meso-zooplankton, detrital nitrogen and silicon, and total CO2).(More)
San Francisco Bay has been considered an HNLC or HNLG (high nutrient low chlorophyll or low growth) region with nonlimiting concentrations of inorganic nutrients yet low standing stocks of phytoplankton. Most of the studies leading to this conclusion come from the South Bay and little is known about nutrient processes and phytoplankton productivity in the(More)
A one-dimensional model of the equatorial Pacific upwelling ecosystem that incorporates two phytoplankton components, two grazers, and three nutrients, Si(OH)4, NO3, and NH4 (Chai et al., Deep-Sea Research II (2002) 2713– 2745), was designed to consider the effects of Si(OH)4 limitation on the diatom growth and ecosystem functioning. Model output was(More)
Primary production in the Northern San Francisco Estuary (SFE) has been declining despite heavy loading of anthropogenic nutrients. The inorganic nitrogen (N) loading comes primarily from municipal wastewater treatment plant (WTP) discharge as ammonium (NH(4)). This study investigated the consequences for river and estuarine phytoplankton of the daily(More)
Si(OH)4, NO3, and TCO2 are shown to be distributed asymmetrically in a north/south direction about the equatorial Pacific using data from WEPOCS III and JGOFS EqPac cruises. Equatorial SiOH4 concentrations are shown to be the product of both geochemical and physical interactions with chemical processes, occurring in at least three regions remote from the(More)
Size and frequency of division were determined for zooxanthellae from nine scleractinian coral species collected in February, 1983 at Discovery Bay, Jamaica, from four depths over a 51 m bathymetric range. Mean diameters of zooxanthellae ranged from 6.4 to 12.6 μm. Small zooxanthellae were found in Madracis mirabilis, Eusmilia fastigiata and Dendrogyra(More)
The use of 15N to measure the flux of nitrogen compounds has become increasingly popular as the techniques and instrumentation for stable isotope analysis have become more widely available. Questions concerning equations for calculating uptake, effect of isotope dilution (in the case of ammonium), duration of incubation, and relationship between(More)
A coupled physical–biological model was developed to simulate the low-silicate, high-nitrate, and low-chlorophyll (LSHNLC) conditions in the equatorial Pacific Ocean and used to compute a detailed budget in the Wyrtki box (5 N– 5 S; 180–90 W) for the major sources and cycling of nitrogen and silicon in the equatorial Pacific. With the incorporation of(More)