CALFED Science Fellows Class of 2003-2004

January 01, 2004
Media Contact— / / 858-534-0580

The Science Fellows program is a project that brings together young scientists, CALFED agency scientists and senior research mentors in collaborative data analysis and research projects relevant to ecosystem management and water supply reliability questions. The CALFED Science Fellows Program will put out a call annually for research proposals from junior scientists (with the backing of their research mentors) for analyses of the immense monitoring databases collected and maintained by the implementing agencies.


Gretchen Rollwagen-Bollens is an assistant research professor in the School of Biological Sciences at Washington State University in Vancouver, Wash., who studies feeding relationships among plankton—very small marine organisms that form the base of the marine food chain.

Rollwagen-Bollens earned a doctorate degree from the Department of Integrative Biology at UC Berkeley for research on planktonic food web dynamics in San Francisco Bay in 2003. One of the main findings of her thesis was that copepods feed mainly on ciliates — not phytoplankton—in saline areas of the bay. In the usual linear model of planktonic food chain dynamics, copepods are normally seen as the primary "grazers" of phytoplankton. Her discovery of an "extra" trophic level between phytoplankton and copepods suggests that there may be less food available for larger animals such as fish than previously thought.

In 2003, Rollwagen-Bollens took a dual position as an adjunct faculty member in the Biology Department at San Francisco State University and research scientist at the Romberg Tiburon Center for Environmental Studies. She began her current position in Washington in August 2004.

Although relocated to the Pacific Northwest, she continues to study planktonic food web dynamics in San Francisco Bay. Her current research looks at the potential for microzooplankton to serve as a source or sink of productivity. She and colleagues are currently measuring feeding rates of copepods and ciliates in Suisun Bay, a northern, upstream area of the bay, which has relatively low salinity levels. She is also examining the degree to which trophic relationships vary with changes in turbidity. Many areas of the San Francisco Bay are shallow and very turbid. Her CALFED Science Fellowship ends in the summer of 2006.

Progress Report Year 1 [CALFEDPostAwdRollwagen-Bollen.pdf]

Progress Report Year 2 [CALFEDInterRptBollens04.pdf]

Final Report [Rollwagen-BollensYr3.pdf]

Project Profile: Protistan Microzooplankton in the Suisan Bay Food Web: Source or Sink?, R/SF-5: 8.1.2003–7.31-2006 [CF.Rollwagen-Bollens.pdf]

Project Abstract

Protistan Microzooplankton in the Suisun Bay Food Web: Source or Sink?
Project Number: R/SF-5
Project Dates: Aug. 03—July 06
Gretchen Rollwagen Bollens/WSU, (360) 546-9115

The goal of this project is to assess the trophic role of small zooplankton (“microzooplankton”) in Suisun Bay in the northern San Francisco Estuary—as grazers of algae and prey for larger zooplankton. Of particular interest are the effects of microzooplankton on the productivity of the lower planktonic food web and the transfer of energy to higher trophic levels such as fish. To do this, researchers are measuring the distribution, abundance, taxonomic composition and feeding rates of both microzooplankton and larger zooplankton. Feeding experiments have shown that grazing rates of microzooplankton are sometimes ten times that of phytoplankton, suggesting that microzooplankton exert strong control of algal abundance. Moreover, in concurrent feeding experiments in which both algae and microzooplankton were presented to larger zooplankton predators, microzooplankton were often the preferred prey. These results indicate that microzooplankton are important in transferring phytoplankton carbon to higher trophic levels.


Sandra Clinton, a postdoctoral researcher in the Department of Integrative Biology at UC Berkeley, studies freshwater and floodplain ecology, food web interactions and the role of science in conservation.

As a CALFED Science Fellow, she is now examining soil fertility in floodplains of Central California and the role of flooding in keeping soils healthy and a source of nourishment for plants. Her findings will have applications for ongoing efforts to restore and manage floodplains in California.

Clinton holds a master’s degree in stream ecology from the Department of Zoology at Arizona State University and a doctorate in ecosystem science from the College of Forest Resources at the University of Washington. Her graduate studies focused on organic matter cycling, microbial production and invertebrate dynamics in sediments beneath and beside streams in Washington.

After earning her doctorate in 2001, she was a postdoctoral researcher at the Center for Streamside Studies at the University of Washington, where she studied the ecology of Seattle streams and the effects of urban activity on their ecological health. Clinton began her current position in 2003.

Her long interest in freshwater ecology, she says, began while working as a technician at the Limnology Center at McGill University in Montreal, her undergraduate alma mater. Many of the questions about lake ecology she investigated while an undergraduate technician she has since had the opportunity to explore for streams and floodplains.

Clinton’s CALFED Science Fellowship ends in 2006. Afterwards, she hopes to work as a researcher at an environmental non-profit organization focused on freshwater issues.

Progress Report Year 1 [CALFEDPostAwdClinton.pdf]

Progress Report Year 2 [CALFEDInterRptClinton04.pdf]

Final Report [CALFEDFinalRptClinton.pdf]

Project Profile: The Influence of Aquatic vs. Terrestrial Production on Soil Invertebrate Communities in a Floodplain Ecosystem, R/SF-1: 7.1.2003–6.30-2006 [CF.Clinton.pdf]

Project Abstract

Impacts of Inundation Regime, Floodplain Vegetation, and Burrowing Animals on the Incorporation of Carbon into Floodplain Soils

Project Number: R/SF-1
Project Dates: July 03–June 06
Sandra Clinton/UCB, (510) 643-9294

Floodplains on the lower reaches of the Consumes River—the last undammed river on the western slope of the Sierra Nevadas—are home to some of the largest stands of riparian forest left in the Central Valley. Because of the land’s ecological value, efforts are underway to convert former farmland to wilderness areas. In this project, scientists are studying the processes influencing the fertility of soils in the region. Of interest is whether algae contribute to soil fertility and if so, to identify processes that transport algae to floodplain soils. Another topic of interest is to identify what kinds of invertebrate communities are associated with different types of riparian meadows and forests and whether the presence of certain invertebrates enhances soil fertility.



Frances Malamud-Roam, a postdoctoral researcher in the Department of Geography at UC Berkeley, is interested in understanding the effects of past and present climate variability on regional ecosystems such as estuaries.

She holds a master’s degree from the Department of Geography at UC Berkeley for research on understanding the role of climate change in initiating a shift from hunter-gatherer societies to more sedentary agrarian ones in China. Among her findings was that rice cultivation likely began in southern China, not India.

In 2002, she earned a doctorate in geography from UC Berkeley. Her doctoral thesis examined paleo-records of pollen and stable carbon isotopes in tidal marsh sediments of San Francisco Bay. From these records, she was able to infer past climate variability in the region.

After earning her doctorate, she received funding from CALFED and the U.S. Geological Survey to co-author a review paper on what is known about California’s paleoclimate. This paper provides CALFED with an overview on the potential impacts of climate change on the Bay-Delta.

Her current research builds on this work. As a CALFED Science Fellow, Malmud-Roam, studies the sources of mineral sediments in tidal marsh habitats of San Francisco estuary. Identifying these sources is important in understanding whether or the degree to which continued sea level rise and climate variability might impede efforts to restore and rebuild tidal marshlands in the area.

Malmud-Roam’s CALFED Science Fellowship ends in 2006. Afterwards, she hopes to land a faculty position in geography in Northern California.

Progress Report Year 1 [CALFEDPostAwdMalmudRoam.pdf]

Final Report [CALFEDInterRptRoam04.pdf]

Project Profile: Sediment Supply and Marsh Development in the San Francisco Estuary, R/SF-3: 9.1.2003–8.31-2006 [CF.Malamud-Roam.pdf]

Project Abstract

Sediment Supply and Marsh Development in San Francisco Estuary
Project Number: R/SF-3
Project Dates: Sept. 03–Aug. 06
Frances Malamud-Roam/UCB, (510) 643-1631

In this project, researchers have developed a set of geochemical "fingerprints" (using trace elements and strontium isotope signatures) that allow them to identify sources of sediments in tidal marshes of the northern San Francisco Estuary. Dams and water diversions have reduced sediment loads, making downstream habitats vulnerable to inundation caused by rising sea level. The goal of this project is to quantify the proportion of sediments coming from local creeks and streams versus those from the larger watershed associated with Sacramento and San Joaquin rivers. To date, researchers have analyzed four sediment cores collected from a relatively small marsh along Novato Creek in Marin. The data suggest that 1) inland sites receive more of their sediments from the local creek than the bayward sites and 2) the sediments on the surface of the marsh are more closely correlated with sediments from Napa River than with sediments passing through the Sacramento-San Joaquin Delta. In the next year, researchers will, among other things, complete a "mixing" model to quantify the fraction of sediments derived from various end-member sources for a series of sediment cores taken from different marshes. The findings will provide a quantitative evaluation of the feasibility of marsh restoration projects in the region, as well as an assessment of how the estuary tidal marshes may fare under rapidly rising global sea level.


Jeff Opperman, a postdoctoral researcher at the Center for Integrated Watershed Science and Management at UC Davis, studies the interactions between rivers and floodplains in driving ecological productivity, habitat quality and species diversity.

As a CALFED Science Fellow, he is currently reviewing what is known about the hydrology, morphology and ecology of historic and present-day Central Valley floodplains. His synthesis of this information will be compiled into a "white paper" for CALFED, which will present a conceptual model of how floodplains function and how to best restore them. He is also helping to organize a series of workshops on floodplain ecology and hydrology.

While a doctoral student in the Department of Environmental Science, Policy and Management at UC Berkeley, Opperman studied the factors influencing the quality of salmon and steelhead habitat in tributaries of the Russian River. He received a doctorate for this research in 2002.

His interest in river and floodplain restoration stems from a long interest in conservation. After graduating with a bachelor's degree in biology from Duke University in 1993, Opperman interned at two nonprofit environmental organizations in Washington D.C., World Wildlife Fund and Conservation International in Washington. He says this experience sparked an interest in understanding more about the role of science in crafting environmental policy. Opperman's CALFED Science Fellowship ends in 2006. Afterwards, he hopes to land an academic position in ecology or environmental science.

Progress Report Year 1 [CALFEDPostAwdOpperman.pdf]

Progress Report Year 2 [CALFEDInterRptOpperman04.pdf]

Final Report [CALFEDFinalRptOpperman.pdf]

Project Profile: An Investigation of Floodplain Habitat for California's Native Fish Species, R/SF-4: 7.1.2003–8.31-2006 [CF.Opperman.pdf]

Project Abstract

An Investigation of Floodplain Habitat for California’s Native Fish Species
Project Number: R/SF-4
Project Dates: July 03–June 06
Jeff Opperman/UCD, (530) 754-9141

The lead scientist on this project recently wrote a draft report for CALFED, in which the general principles of floodplain geomorphology, hydrology, and ecology for the Central Valley were reviewed. A second document will review the historical extent and losses of floodplains, describe restoration approaches in the valley and elsewhere and discuss potential implications of climate change on floodplain hydrology and ecology. The scientist and collaborators have developed a technique for identifying floodplains inundated by ecologically important flows and have used the technique to document the rarity of this type of habitat in California. More recently, the scientist has been studying growth rates of juvenile chinook raised in either floodplain or riverine habitats of the Consumes River Preserve. Results show that fish grown in floodplains grow faster than those raised in the river. Subsequent analyses will compare the mercury content of these fish.



Noah Snyder is a former CALFED Science Fellow who was recently hired as an assistant professor in the Department of Geology and Geophysics at Boston College.

As a fluvial geomorphologist, Snyder studies how rivers shape the landscape. He is especially interested in understanding erosion and sediment transport in rivers.

Snyder earned his doctorate in geology from the Massachusetts Institute of Technology in 2001. His thesis looked at how tectonic processes alter erosion rates in coastal streams in Northern California.

After graduating, he became a postdoctoral researcher and CALFED Science Fellow at the U.S. Geological Survey Pacific Science Center in Santa Cruz, Calif. His postdoctoral research focused on understanding sediment transport in the Yuba River. This topic is of interest to resource managers because of the river's importance in providing spawning habitat for federally protected salmon and because of interest in exploring the feasibility of restoring salmon habitat upstream of the Englebright Dam on the upper Yuba River.

Snyder continues to study sedimentation in the Yuba River and in streams in Death Valley. He has also begun studies of sediment transport and erosion in northern New England rivers – work that may help restore Atlantic salmon in the region.

Besides his research, Snyder, now teaches undergraduate classes in geology, geomorphology and rivers. He began his position at Boston College in the summer of 2004.

Progress Report Year 1 [CALFEDPostAwdSnyder.pdf]

Final Report [CALFEDfinalSnyder.pdf]

Project Profile: Using Stratigraphic and Hydrologic Data from the Yuba River System to Develop Reliable Sediment Transport Predictions, R/SF-6: 12.1.2002–11.30-2004 [CF.Snyder.pdf]


John Stella, a doctoral student in the Department of Environmental Science, Policy and Management at UC Berkeley, studies river ecosystems and ways to improve the management and restoration of highly altered river systems.

His interest in rivers and their ecology began in the 1990s while working for the East Bay Conservation Corps, a youth development agency in Oakland, Calif. As a supervisor and counselor, Stella taught urban youth how to maintain local river systems by doing things like clearing flood control channels, trimming trees and building hiking trails. This outreach to underserved youth led to a curiosity in the science of rivers and creeks, particularly those whose hydrology have been dramatically altered by human activities.

In 2000, twelve years after obtaining a bachelor’s degree in architecture from Yale University, Stella entered a doctoral program in environmental science to pursue his interest in river ecology. His doctoral research examines the effects of hydrological change on the sustainability and restoration of cottonwood and willow forests in the San Joaquin Valley, an area in which huge amounts of fresh water are routinely diverted for farm irrigation and to control flooding.

While in graduate school Stella has also been working for a small environmental consulting firm in Berkeley. In this capacity, he has helped survey and monitor stream habitats in the Merced River corridor and Presidio in San Francisco, among other things. Many of these projects were funded by CALFED.

As a CALFED Science Fellow, Stella continues to share his scientific and technical expertise on river systems in Northern and Central California with state managers and scientists. He recently reviewed a salmon restoration plan for the Merced River and a set of salmon-restoration protocols for the California Department of Fish & Game.

Stella is in the process of writing academic papers on his research findings and their applications to resource management. He plans to earn his doctorate in May 2005 and afterwards hopes to land a faculty position in environmental science at a California university.

Progress Report Year 1 [CALFEDPostAwdStella.pdf]

Progress Report Year 2 [CALFEDInterRptStella04.pdf]

Final Report [CALFEDfinalStella.pdf]

Project Profile: A Mechanistic Model to Evaluate and Improve Riparian Restoration Success, R/SF-2: 4.1.2003–11.30.2005 [CF.Stella.pdf]

About California Sea Grant

NOAA’s California Sea Grant College Program funds marine research, education and outreach throughout California. Our headquarters is at Scripps Institution of Oceanography, University of California, San Diego; we are one of 33 Sea Grant programs in the National Oceanic and Atmospheric Administration (NOAA), U.S. Department of Commerce.