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 (NO 3) in San Francisco Bay (SFB) is unavailable to the resident phytoplankton most of the year due to the presence of ammonium (NH 4) at inhibitory concentrations that prevents NO 3 uptake. Low annual primary productivity in this turbid estuary is generally attributed to the poor irradiance conditions. However, this may(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)
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)
Keywords: San Francisco Estuary primary production phytoplankton carbon ammonium nitrate a b s t r a c t We describe the results of a series of 96-h enclosure experiments conducted using water from stations in the northern San Francisco Estuary (SFE) along a gradient in ammonium (NH 4) and nitrate (NO 3) concentrations. Using dual-labeled 13 C/ 15 N(More)
Anthropogenic activities are altering total nutrient loads to many estuaries and freshwaters, resulting in high loads not only of total nitrogen (N), but in some cases, of chemically reduced forms, notably NH 1 4. Long thought to be the preferred form of N for phytoplankton uptake, NH 1 4 may actually suppress overall growth when concentrations are(More)
The effect of equivalent additions of nitrogen (N, 30–40 µM-N) in different forms (ammonium, NH + 4 , and nitrate, NO − 3) under conditions of different light exposure on phytoplankton community composition was studied in a series of four, 5-day enclosure experiments on water collected from the nutrient-rich San Francisco Bay Delta over 2 years. Overall,(More)
In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: Keywords: San Francisco Estuary primary production phytoplankton carbon ammonium(More)
The northern San Francisco Estuary (nSFE) is an urban estuary supplied with anthropogenic nutrient inputs, yet spring blooms are uncommon and phytoplankton biomass is low. The low levels of chlorophyll (<5 µg L−1) have likely contributed to declines in several native fishes, and there is a need to evaluate the conditions that could allow for increased(More)
Salt marsh restoration is hypothesized to provide shoreline stabilization, increased fish habitat, and organic carbon subsidies for estuarine food webs. Organic carbon comes from diverse primary producers that differ in carbon fixation rates and areal extent within wetland systems. This study was designed to obtain some of the first estimates of the(More)
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