Craig A Stricker, PhD
Craig Stricker is an ecologist at the Fort Collins Science Center that specializes in the application of chemical and isotopic tracers for addressing societally relevant questions related to ecosystem ecology. His research interests are focused on biogeochemistry, food webs, and animal resource allocation and movement.
Geology, Geophysics, and Geochemistry Stable Isotope Laboratory (GSIL)
Geology, Geophysics, and Geochemistry Stable Isotope Laboratory (GSIL)
The GSIL is a state-of-the-art facility located on the Denver Federal Center that specializes in the measurement of light stable isotope — Hydrogen (H), Carbon (C), Nitrogen (N), Oxygen (O), and Sulfur (S) — compositions and other chemical and biomarker analytes in matrices relevant to the Earth sciences.
Research Highlights
Research Highlights
- Continental-scale nutrient and contaminant delivery by Pacific salmon
- Diet and macronutrient assimilation in an Arctic predator
- Animal tracing with sulfur isotopes
- Effects of protein overconsumption limit dietary adaptation in an apex predator
- Carbon chemistry of peatlands in the southeastern USA
- Design, development, and implementation of IsoBank
- Diet energy density associated with survival, habitat, and population dynamics
As an ecologist at the Fort Collins Science Center, Craig Stricker’s research program focuses on an improved understanding of the roles of hydrology, biogeochemistry, and food web interactions on ecosystem structure and function with the goal of assisting land managers. His expertise in chemical and isotopic tracers offers novel insights in ecosystem ecology and has benefitted multidisciplinary collaborations across a variety of state, federal, and academic institutions. Tracer-based approaches to studying wildlife and ecosystems is a capability unique to Stricker’s research and the Fort Collins Science Center with examples ranging from wildlife nutrition, trophic dynamics, impacts of invasive species, animal movements and phenology, biogeochemistry, and environmental stressors such as fire and drought. The spatial domain of his work ranges from discrete habitats, regional assessments, to continental and oceanic basins, with studies from the sub-tropics to the high Arctic. Results of these projects inform on species life history and fitness to ecosystem health and function, but also offer frameworks for monitoring programs, model development, restoration, and risk assessment.
Professional Experience
2009 - Present, Research Biologist, US Geological Survey, Fort Collins Science Center
2005 - 2008, Research Biologist, US Geological Survey, Geologic Division - Crustal, Geology, and Geochemistry
2002 - 2004, Mendenhall Postdoctoral Fellow, US Geological Survey, Geologic Division - Crustal, Geology, and Geochemistry
Education and Certifications
PhD in Limnology, Michigan State University, 2003
MS in Aquatic Ecology, Central Michigan University, 1997
BS in Biology, Central Michigan University, 1994
Science and Products
Filter Total Items: 22
No Result Found
Filter Total Items: 86
Comment on "Donders, T.H. 2014. Middle Holocene humidity increase in Florida: climate or sea-level? Quaternary Science Reviews 103:170-174." Comment on "Donders, T.H. 2014. Middle Holocene humidity increase in Florida: climate or sea-level? Quaternary Science Reviews 103:170-174."
Donders (2014) has recently proposed that the climate of Florida became progressively wetter over the past 5000 years in response to a marked strengthening of the El Niño regime. This reconstruction is largely based on a re-analysis of pollen records from regions north of Lake Okeechobee (Fig. 1) using a new set of pollen transfer functions. Donders concluded that a latitudinal gradient...
Authors
Paul H. Glaser, Barbara Hansen, Joseph J. Donovan, Thomas Givnish, Craig Stricker, John Volin
Age-specific vibrissae growth rates: a tool for determining the timing of ecologically important events in Steller sea lions Age-specific vibrissae growth rates: a tool for determining the timing of ecologically important events in Steller sea lions
Steller sea lions (SSL; Eumetopias jubatus) grow their vibrissae continually, providing a multiyear record suitable for ecological and physiological studies based on stable isotopes. An accurate age-specific vibrissae growth rate is essential for registering a chronology along the length of the record, and for interpreting the timing of ecologically important events. We utilized four...
Authors
L.D. Rea, A.M. Christ, A.B. Hayden, V.K. Stegall, S.D. Farley, Craig Stricker, J.E. Mellish, John Maniscalco, J.N. Waite, V.N. Burkanov, K.W. Pitcher
Individual specialization in the foraging habits of female bottlenose dolphins living in a trophically diverse and habitat rich estuary Individual specialization in the foraging habits of female bottlenose dolphins living in a trophically diverse and habitat rich estuary
We examine individual specialization in foraging habits (foraging habitat and trophic level) of female bottlenose dolphins (Tursiops truncatus) resident in Sarasota Bay, Florida, USA, by analyzing time series of stable isotope (δ15N and δ13C) values in sequential growth layer groups within teeth. The isotope data provide a chronology of foraging habits over the lifetime of the individual...
Authors
Sam Rossman, Peggy H. Ostrom, Megan Stolen, Nélio B. Barros, Hasand Gandhi, Craig Stricker, Randall Wells
Stable isotope values in pup vibrissae reveal geographic variation in diets of gestating Steller sea lions Eumetopias jubatus Stable isotope values in pup vibrissae reveal geographic variation in diets of gestating Steller sea lions Eumetopias jubatus
Multiple factors, including limitation in food resources, have been proposed as possible causes for the lack of recovery of the endangered western segment of the Steller sea lion population in the United States. Because maternal body condition has important consequences on fetal development and neonatal survival, the diets of pregnant females may be particularly important in regulating...
Authors
Rick Scherer, Andrew Doll, Lorrie Rea, Aaron Christ, Craig Stricker, Briana Witteveen, Thomas Kline, Carolyn Kurle, Michael B. Wunder
Stable carbon and nitrogen isotope trophic enrichment factors for Steller sea lion vibrissae relative to milk and fish/invertebrate diets Stable carbon and nitrogen isotope trophic enrichment factors for Steller sea lion vibrissae relative to milk and fish/invertebrate diets
Nutritional constraints have been proposed as a contributor to population declines in the endangered Steller sea lion Eumetopias jubatus in some regions of the North Pacific. Isotopic analysis of vibrissae (whiskers) is a potentially useful approach to resolving the nutritional ecology of this species because long-term (up to 8 yr) dietary information is sequentially recorded and...
Authors
Craig Stricker, Aaron Christ, Michael Wunder, Andrew C. Doll, Sean Farley, Lorrie Rea, David A. S. Rosen, R. Scherer, Dominic Tollit
Improved arrival-date estimates of Arctic-breeding Dunlin (Calidris alpina arcticola) Improved arrival-date estimates of Arctic-breeding Dunlin (Calidris alpina arcticola)
The use of stable isotopes in animal ecology depends on accurate descriptions of isotope dynamics within individuals. The prevailing assumption that laboratory-derived isotopic parameters apply to free-living animals is largely untested. We used stable carbon isotopes (δ13C) in whole blood from migratory Dunlin (Calidris alpina arcticola) to estimate an in situ turnover rate and...
Authors
Andrew Doll, Richard Lanctot, Craig Stricker, Stephen Yezerinac, Michael B. Wunder
Foraging habits in a generalist predator: sex and age influence habitat selection and resource use among bottlenose dolphins (Tursiops truncatus) Foraging habits in a generalist predator: sex and age influence habitat selection and resource use among bottlenose dolphins (Tursiops truncatus)
This study examines resource use (diet, habitat use, and trophic level) within and among demographic groups (males, females, and juveniles) of bottlenose dolphins (Tursiops truncatus). We analyzed the δ13C and δ15N values of 15 prey species constituting 84% of the species found in stomach contents. We used these data to establish a trophic enrichment factor (TEF) to inform dietary...
Authors
Sam Rossman, Elizabeth McCabe, Nelio Barros, Hasand Gandhi, Peggy Ostrom, Craig Stricker, Randall S. Wells
Metamorphosis alters contaminants and chemical tracers in insects: implications for food webs Metamorphosis alters contaminants and chemical tracers in insects: implications for food webs
Insects are integral to most freshwater and terrestrial food webs, but due to their accumulation of environmental pollutants they are also contaminant vectors that threaten reproduction, development, and survival of consumers. Metamorphosis from larvae to adult can cause large chemical changes in insects, altering contaminant concentrations and fractionation of chemical tracers used to...
Authors
Johanna Kraus, David M. Walters, Jeff Wesner, Craig Stricker, Travis S. Schmidt, Robert Zuellig
Unexpected hydrogen isotope variation in oceanic pelagic seabirds Unexpected hydrogen isotope variation in oceanic pelagic seabirds
Hydrogen isotopes have significantly enhanced our understanding of the biogeography of migratory animals. The basis for this methodology lies in predictable, continental patterns of precipitation δD values that are often reflected in an organism’s tissues. δD variation is not expected for oceanic pelagic organisms whose dietary hydrogen (water and organic hydrogen in prey) is transferred...
Authors
Peggy H. Ostrom, Anne Wiley, Sam Rossman, Craig Stricker, Helen James
Methylmercury production in sediment from agricultural and non-agricultural wetlands in the Yolo Bypass, California, USA Methylmercury production in sediment from agricultural and non-agricultural wetlands in the Yolo Bypass, California, USA
As part of a larger study of mercury (Hg) biogeochemistry and bioaccumulation in agricultural (rice growing) and non-agricultural wetlands in California's Central Valley, USA, seasonal and spatial controls on methylmercury (MeHg) production were examined in surface sediment. Three types of shallowly-flooded agricultural wetlands (white rice, wild rice, and fallow fields) and two types of...
Authors
Mark Marvin-DiPasquale, Lisamarie Windham-Myers, Jennifer Agee, Evangelos Kakouros, Le Kieu, Jacob A. Fleck, Charles Alpers, Craig Stricker
Selenium and mercury concentrations in harbor seals (Phoca vitulina) from central California: Health implications in an urbanized estuary Selenium and mercury concentrations in harbor seals (Phoca vitulina) from central California: Health implications in an urbanized estuary
We measured total selenium and total mercury concentrations ([TSe] and [THg]) in hair (n = 138) and blood (n = 73) of harbor seals (Phoca vitulina) from California to assess variation by geography and sex, and inferred feeding relationships based on carbon, nitrogen, and sulfur stable isotopes. Harbor seals from Hg-contaminated sites had significantly greater [THg], and lesser [TSe] and...
Authors
Elizabeth McHuron, James Harvey, J. Castellini, Craig Stricker, Todd M. O'Hara
Continental-scale, seasonal movements of a heterothermic migratory tree bat Continental-scale, seasonal movements of a heterothermic migratory tree bat
Long-distance migration evolved independently in bats and unique migration behaviors are likely, but because of their cryptic lifestyles, many details remain unknown. North American hoary bats (Lasiurus cinereus cinereus) roost in trees year-round and probably migrate farther than any other bats, yet we still lack basic information about their migration patterns and wintering locations...
Authors
Paul M. Cryan, Craig Stricker, Michael B. Wunder
Non-USGS Publications**
Uzarski, D., Burton, T. & Stricker, C. Hydrobiologia (2001) 455: 137. doi:10.1023/A:1011929719866
Burton, T.M., Uzarski, D.G., Gathman, J.P. et al. Wetlands (1999) 19: 869. doi:10.1007/BF03161789
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
Filter Total Items: 22
No Result Found
Filter Total Items: 86
Comment on "Donders, T.H. 2014. Middle Holocene humidity increase in Florida: climate or sea-level? Quaternary Science Reviews 103:170-174." Comment on "Donders, T.H. 2014. Middle Holocene humidity increase in Florida: climate or sea-level? Quaternary Science Reviews 103:170-174."
Donders (2014) has recently proposed that the climate of Florida became progressively wetter over the past 5000 years in response to a marked strengthening of the El Niño regime. This reconstruction is largely based on a re-analysis of pollen records from regions north of Lake Okeechobee (Fig. 1) using a new set of pollen transfer functions. Donders concluded that a latitudinal gradient...
Authors
Paul H. Glaser, Barbara Hansen, Joseph J. Donovan, Thomas Givnish, Craig Stricker, John Volin
Age-specific vibrissae growth rates: a tool for determining the timing of ecologically important events in Steller sea lions Age-specific vibrissae growth rates: a tool for determining the timing of ecologically important events in Steller sea lions
Steller sea lions (SSL; Eumetopias jubatus) grow their vibrissae continually, providing a multiyear record suitable for ecological and physiological studies based on stable isotopes. An accurate age-specific vibrissae growth rate is essential for registering a chronology along the length of the record, and for interpreting the timing of ecologically important events. We utilized four...
Authors
L.D. Rea, A.M. Christ, A.B. Hayden, V.K. Stegall, S.D. Farley, Craig Stricker, J.E. Mellish, John Maniscalco, J.N. Waite, V.N. Burkanov, K.W. Pitcher
Individual specialization in the foraging habits of female bottlenose dolphins living in a trophically diverse and habitat rich estuary Individual specialization in the foraging habits of female bottlenose dolphins living in a trophically diverse and habitat rich estuary
We examine individual specialization in foraging habits (foraging habitat and trophic level) of female bottlenose dolphins (Tursiops truncatus) resident in Sarasota Bay, Florida, USA, by analyzing time series of stable isotope (δ15N and δ13C) values in sequential growth layer groups within teeth. The isotope data provide a chronology of foraging habits over the lifetime of the individual...
Authors
Sam Rossman, Peggy H. Ostrom, Megan Stolen, Nélio B. Barros, Hasand Gandhi, Craig Stricker, Randall Wells
Stable isotope values in pup vibrissae reveal geographic variation in diets of gestating Steller sea lions Eumetopias jubatus Stable isotope values in pup vibrissae reveal geographic variation in diets of gestating Steller sea lions Eumetopias jubatus
Multiple factors, including limitation in food resources, have been proposed as possible causes for the lack of recovery of the endangered western segment of the Steller sea lion population in the United States. Because maternal body condition has important consequences on fetal development and neonatal survival, the diets of pregnant females may be particularly important in regulating...
Authors
Rick Scherer, Andrew Doll, Lorrie Rea, Aaron Christ, Craig Stricker, Briana Witteveen, Thomas Kline, Carolyn Kurle, Michael B. Wunder
Stable carbon and nitrogen isotope trophic enrichment factors for Steller sea lion vibrissae relative to milk and fish/invertebrate diets Stable carbon and nitrogen isotope trophic enrichment factors for Steller sea lion vibrissae relative to milk and fish/invertebrate diets
Nutritional constraints have been proposed as a contributor to population declines in the endangered Steller sea lion Eumetopias jubatus in some regions of the North Pacific. Isotopic analysis of vibrissae (whiskers) is a potentially useful approach to resolving the nutritional ecology of this species because long-term (up to 8 yr) dietary information is sequentially recorded and...
Authors
Craig Stricker, Aaron Christ, Michael Wunder, Andrew C. Doll, Sean Farley, Lorrie Rea, David A. S. Rosen, R. Scherer, Dominic Tollit
Improved arrival-date estimates of Arctic-breeding Dunlin (Calidris alpina arcticola) Improved arrival-date estimates of Arctic-breeding Dunlin (Calidris alpina arcticola)
The use of stable isotopes in animal ecology depends on accurate descriptions of isotope dynamics within individuals. The prevailing assumption that laboratory-derived isotopic parameters apply to free-living animals is largely untested. We used stable carbon isotopes (δ13C) in whole blood from migratory Dunlin (Calidris alpina arcticola) to estimate an in situ turnover rate and...
Authors
Andrew Doll, Richard Lanctot, Craig Stricker, Stephen Yezerinac, Michael B. Wunder
Foraging habits in a generalist predator: sex and age influence habitat selection and resource use among bottlenose dolphins (Tursiops truncatus) Foraging habits in a generalist predator: sex and age influence habitat selection and resource use among bottlenose dolphins (Tursiops truncatus)
This study examines resource use (diet, habitat use, and trophic level) within and among demographic groups (males, females, and juveniles) of bottlenose dolphins (Tursiops truncatus). We analyzed the δ13C and δ15N values of 15 prey species constituting 84% of the species found in stomach contents. We used these data to establish a trophic enrichment factor (TEF) to inform dietary...
Authors
Sam Rossman, Elizabeth McCabe, Nelio Barros, Hasand Gandhi, Peggy Ostrom, Craig Stricker, Randall S. Wells
Metamorphosis alters contaminants and chemical tracers in insects: implications for food webs Metamorphosis alters contaminants and chemical tracers in insects: implications for food webs
Insects are integral to most freshwater and terrestrial food webs, but due to their accumulation of environmental pollutants they are also contaminant vectors that threaten reproduction, development, and survival of consumers. Metamorphosis from larvae to adult can cause large chemical changes in insects, altering contaminant concentrations and fractionation of chemical tracers used to...
Authors
Johanna Kraus, David M. Walters, Jeff Wesner, Craig Stricker, Travis S. Schmidt, Robert Zuellig
Unexpected hydrogen isotope variation in oceanic pelagic seabirds Unexpected hydrogen isotope variation in oceanic pelagic seabirds
Hydrogen isotopes have significantly enhanced our understanding of the biogeography of migratory animals. The basis for this methodology lies in predictable, continental patterns of precipitation δD values that are often reflected in an organism’s tissues. δD variation is not expected for oceanic pelagic organisms whose dietary hydrogen (water and organic hydrogen in prey) is transferred...
Authors
Peggy H. Ostrom, Anne Wiley, Sam Rossman, Craig Stricker, Helen James
Methylmercury production in sediment from agricultural and non-agricultural wetlands in the Yolo Bypass, California, USA Methylmercury production in sediment from agricultural and non-agricultural wetlands in the Yolo Bypass, California, USA
As part of a larger study of mercury (Hg) biogeochemistry and bioaccumulation in agricultural (rice growing) and non-agricultural wetlands in California's Central Valley, USA, seasonal and spatial controls on methylmercury (MeHg) production were examined in surface sediment. Three types of shallowly-flooded agricultural wetlands (white rice, wild rice, and fallow fields) and two types of...
Authors
Mark Marvin-DiPasquale, Lisamarie Windham-Myers, Jennifer Agee, Evangelos Kakouros, Le Kieu, Jacob A. Fleck, Charles Alpers, Craig Stricker
Selenium and mercury concentrations in harbor seals (Phoca vitulina) from central California: Health implications in an urbanized estuary Selenium and mercury concentrations in harbor seals (Phoca vitulina) from central California: Health implications in an urbanized estuary
We measured total selenium and total mercury concentrations ([TSe] and [THg]) in hair (n = 138) and blood (n = 73) of harbor seals (Phoca vitulina) from California to assess variation by geography and sex, and inferred feeding relationships based on carbon, nitrogen, and sulfur stable isotopes. Harbor seals from Hg-contaminated sites had significantly greater [THg], and lesser [TSe] and...
Authors
Elizabeth McHuron, James Harvey, J. Castellini, Craig Stricker, Todd M. O'Hara
Continental-scale, seasonal movements of a heterothermic migratory tree bat Continental-scale, seasonal movements of a heterothermic migratory tree bat
Long-distance migration evolved independently in bats and unique migration behaviors are likely, but because of their cryptic lifestyles, many details remain unknown. North American hoary bats (Lasiurus cinereus cinereus) roost in trees year-round and probably migrate farther than any other bats, yet we still lack basic information about their migration patterns and wintering locations...
Authors
Paul M. Cryan, Craig Stricker, Michael B. Wunder
Non-USGS Publications**
Uzarski, D., Burton, T. & Stricker, C. Hydrobiologia (2001) 455: 137. doi:10.1023/A:1011929719866
Burton, T.M., Uzarski, D.G., Gathman, J.P. et al. Wetlands (1999) 19: 869. doi:10.1007/BF03161789
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.