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: 21
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Filter Total Items: 83
Mechanisms associated with an advance in the timing of seasonal reproduction in an urban songbird
The colonization of urban environments by animals is often accompanied by earlier breeding and associated changes in seasonal schedules. Accelerated timing of seasonal reproduction in derived urban populations is a potential cause of evolutionary divergence from ancestral populations if differences in physiological processes that regulate reproductive timing become fixed over time. We...
Authors
Adam M. Fudickar, Timothy J Greives, Mikas Abolins-Abols, Jonathan W. Atwell, Simone L. Meddle, Guillermo Friis, Craig A. Stricker, Ellen D. Ketterson
Opinion: Why we need a centralized repository for isotopic data
Stable isotopes encode and integrate the origin of matter; thus, their analysis offers tremendous potential to address questions across diverse scientific disciplines (1, 2). Indeed, the broad applicability of stable isotopes, coupled with advancements in high-throughput analysis, have created a scientific field that is growing exponentially, and generating data at a rate paralleling the...
Authors
Jonathan N. Pauli, Seth D. Newsome, Joseph A. Cook, Chris Harrod, Shawn A. Steffan, Christopher M. Baker, Merav Ben-David, David Bloom, Gabriel J. Bowen, Thure E. Cerling, Carla Cicero, Craig Cook, Michelle Dohm, Prarthana S. Dharampal, Gary R. Graves, Robert Gropp, Keith A. Hobson, Chris E. Jordan, Bruce MacFadden, Suzanne E. Pilaar Birch, Jorrit Poelen, Sujeevan Ratnasingham, Laura Russell, Craig A. Stricker, Mark D. Uhen, Christopher T. Yarnes, Brian Hayden
Metamorphosis affects metal concentrations and isotopic signatures in a mayfly (Baetis tricaudatus): Implications for the aquatic-terrestrial transfer of metals
Insect metamorphosis often results in substantial chemical changes that can alter contaminant concentrations and fractionate isotopes. We exposed larval mayflies (Baetis tricaudatus) and their food (periphyton) to an aqueous zinc gradient (3-340 µg Zn/l) and measured zinc concentrations at different stages of metamorphosis: larval, subimago, and imago. We also measured changes in stable...
Authors
Jeff S. Wesner, David C Walters, Travis Schmidt, Johanna M. Kraus, Craig A. Stricker, William H. Clements, Ruth E. Wolf
Trophic pathways supporting juvenile Chinook and Coho salmon in the glacial Susitna River, Alaska: patterns of freshwater, marine, and terrestrial resource use across a seasonally dynamic habitat mosaic
Contributions of terrestrial-, freshwater-, and marine-derived prey resources to stream fishes vary over time and space, altering the energy pathways that regulate production. In this study, we determined large-scale use of these resources by juvenile Chinook and coho salmon (Oncorhynchus tshawytscha and Oncorhynchus kisutch, respectively) in the glacial Susitna River, Alaska. We...
Authors
Kristin M. Rine, Mark S. Wipfli, Erik R. Schoen, Timothy L. Nightengale, Craig A. Stricker
Isotopic incorporation and the effects of fasting and dietary lipid content on isotopic discrimination in large carnivorous mammals
There has been considerable emphasis on understanding isotopic discrimination for diet estimation in omnivores. However, discrimination may differ for carnivores, particularly species that consume lipid-rich diets. Here, we examined the potential implications of several factors when using stable isotopes to estimate the diets of bears, which can consume lipid-rich diets and...
Authors
Karyn D. Rode, Craig A. Stricker, Joy A Erlenbach, Charles T. Robbins, Seth Cherry, Seth D. Newsome, Amy Cutting, Shannon Jensen, Gordon Stenhouse, Matt L. Brooks, Amy Hash, Nicole Nicassio
Reproductive allochrony in seasonally sympatric populations maintained by differential response to photoperiod: Implications for population divergence and response to climate change
Reproductive allochrony presents a potential barrier to gene flow and is common in seasonally sympatric migratory and sedentary birds. Mechanisms mediating reproductive allochrony can influence population divergence and the capacity of populations to respond to environmental change. We asked whether reproductive allochrony in seasonally sympatric birds results from a difference in...
Authors
Adam M. Fudickar, T.J. Grieves, Jonathan W. Atwell, Craig A. Stricker, Ellen D. Ketterson
Wood decay in desert riverine environments
Floodplain forests and the woody debris they produce are major components of riverine ecosystems in many arid and semiarid regions (drylands). We monitored breakdown and nitrogen dynamics in wood and bark from a native riparian tree, Fremont cottonwood (Populus deltoides subsp. wislizeni), along four North American desert streams. We placed locally-obtained, fresh, coarse material [disks...
Authors
Douglas C. Andersen, Craig A. Stricker, S. Mark Nelson
Isotopic insights into biological regulation of zinc in contaminated systems
Aquatic organisms use a variety of biogeochemical reactions to regulate essential and non-essential trace metals. Many of these mechanisms can lead to isotopic fractionation, thus measurement of metal isotopes may yield insights into the processes by which organisms respond to metal exposure. We illustrate these concepts with two case studies, one involving an intra- and the other an...
Authors
Richard B. Wanty, Laurie S. Balistrieri, Jeff S. Wesner, David C Walters, Travis Schmidt, Francesca Podda, Giovanni De Giudici, Craig A. Stricker, Johanna M. Kraus, Pierfranco Lattanzi, Ruth E. Wolf, Rosa Cidu
Ecotoxicoparasitology: Understanding mercury concentrations in gut contents, intestinal helminths and host tissues of Alaskan gray wolves (Canis lupus)
Some gastrointestinal helminths acquire nutrients from the lumen contents in which they live; thus, they may be exposed to non-essential elements, such as mercury (Hg), during feeding. The objectives of this study were: 1) determine the total mercury concentrations ([THg]) in Gray wolves (Canis lupus) and their parasites, and 2) use stable isotopes to evaluate the trophic relationships...
Authors
Ashley K. McGrew, Todd M. O’Hara, Craig A. Stricker, Margaret Castellini, Kimberlee B. Beckmen, Mo D. Salman, Lora R. Ballweber
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 CS Hansen, Joseph J. Donovan, Thomas J. Givnish, Craig A. Stricker, John C. Volin
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 A. Stricker, J.E. Mellish, John M. 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
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, Nelio B. Barros, Hasand Gandhi, Craig A. Stricker, Randall S. Wells
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: 21
No Result Found
Filter Total Items: 83
Mechanisms associated with an advance in the timing of seasonal reproduction in an urban songbird
The colonization of urban environments by animals is often accompanied by earlier breeding and associated changes in seasonal schedules. Accelerated timing of seasonal reproduction in derived urban populations is a potential cause of evolutionary divergence from ancestral populations if differences in physiological processes that regulate reproductive timing become fixed over time. We...
Authors
Adam M. Fudickar, Timothy J Greives, Mikas Abolins-Abols, Jonathan W. Atwell, Simone L. Meddle, Guillermo Friis, Craig A. Stricker, Ellen D. Ketterson
Opinion: Why we need a centralized repository for isotopic data
Stable isotopes encode and integrate the origin of matter; thus, their analysis offers tremendous potential to address questions across diverse scientific disciplines (1, 2). Indeed, the broad applicability of stable isotopes, coupled with advancements in high-throughput analysis, have created a scientific field that is growing exponentially, and generating data at a rate paralleling the...
Authors
Jonathan N. Pauli, Seth D. Newsome, Joseph A. Cook, Chris Harrod, Shawn A. Steffan, Christopher M. Baker, Merav Ben-David, David Bloom, Gabriel J. Bowen, Thure E. Cerling, Carla Cicero, Craig Cook, Michelle Dohm, Prarthana S. Dharampal, Gary R. Graves, Robert Gropp, Keith A. Hobson, Chris E. Jordan, Bruce MacFadden, Suzanne E. Pilaar Birch, Jorrit Poelen, Sujeevan Ratnasingham, Laura Russell, Craig A. Stricker, Mark D. Uhen, Christopher T. Yarnes, Brian Hayden
Metamorphosis affects metal concentrations and isotopic signatures in a mayfly (Baetis tricaudatus): Implications for the aquatic-terrestrial transfer of metals
Insect metamorphosis often results in substantial chemical changes that can alter contaminant concentrations and fractionate isotopes. We exposed larval mayflies (Baetis tricaudatus) and their food (periphyton) to an aqueous zinc gradient (3-340 µg Zn/l) and measured zinc concentrations at different stages of metamorphosis: larval, subimago, and imago. We also measured changes in stable...
Authors
Jeff S. Wesner, David C Walters, Travis Schmidt, Johanna M. Kraus, Craig A. Stricker, William H. Clements, Ruth E. Wolf
Trophic pathways supporting juvenile Chinook and Coho salmon in the glacial Susitna River, Alaska: patterns of freshwater, marine, and terrestrial resource use across a seasonally dynamic habitat mosaic
Contributions of terrestrial-, freshwater-, and marine-derived prey resources to stream fishes vary over time and space, altering the energy pathways that regulate production. In this study, we determined large-scale use of these resources by juvenile Chinook and coho salmon (Oncorhynchus tshawytscha and Oncorhynchus kisutch, respectively) in the glacial Susitna River, Alaska. We...
Authors
Kristin M. Rine, Mark S. Wipfli, Erik R. Schoen, Timothy L. Nightengale, Craig A. Stricker
Isotopic incorporation and the effects of fasting and dietary lipid content on isotopic discrimination in large carnivorous mammals
There has been considerable emphasis on understanding isotopic discrimination for diet estimation in omnivores. However, discrimination may differ for carnivores, particularly species that consume lipid-rich diets. Here, we examined the potential implications of several factors when using stable isotopes to estimate the diets of bears, which can consume lipid-rich diets and...
Authors
Karyn D. Rode, Craig A. Stricker, Joy A Erlenbach, Charles T. Robbins, Seth Cherry, Seth D. Newsome, Amy Cutting, Shannon Jensen, Gordon Stenhouse, Matt L. Brooks, Amy Hash, Nicole Nicassio
Reproductive allochrony in seasonally sympatric populations maintained by differential response to photoperiod: Implications for population divergence and response to climate change
Reproductive allochrony presents a potential barrier to gene flow and is common in seasonally sympatric migratory and sedentary birds. Mechanisms mediating reproductive allochrony can influence population divergence and the capacity of populations to respond to environmental change. We asked whether reproductive allochrony in seasonally sympatric birds results from a difference in...
Authors
Adam M. Fudickar, T.J. Grieves, Jonathan W. Atwell, Craig A. Stricker, Ellen D. Ketterson
Wood decay in desert riverine environments
Floodplain forests and the woody debris they produce are major components of riverine ecosystems in many arid and semiarid regions (drylands). We monitored breakdown and nitrogen dynamics in wood and bark from a native riparian tree, Fremont cottonwood (Populus deltoides subsp. wislizeni), along four North American desert streams. We placed locally-obtained, fresh, coarse material [disks...
Authors
Douglas C. Andersen, Craig A. Stricker, S. Mark Nelson
Isotopic insights into biological regulation of zinc in contaminated systems
Aquatic organisms use a variety of biogeochemical reactions to regulate essential and non-essential trace metals. Many of these mechanisms can lead to isotopic fractionation, thus measurement of metal isotopes may yield insights into the processes by which organisms respond to metal exposure. We illustrate these concepts with two case studies, one involving an intra- and the other an...
Authors
Richard B. Wanty, Laurie S. Balistrieri, Jeff S. Wesner, David C Walters, Travis Schmidt, Francesca Podda, Giovanni De Giudici, Craig A. Stricker, Johanna M. Kraus, Pierfranco Lattanzi, Ruth E. Wolf, Rosa Cidu
Ecotoxicoparasitology: Understanding mercury concentrations in gut contents, intestinal helminths and host tissues of Alaskan gray wolves (Canis lupus)
Some gastrointestinal helminths acquire nutrients from the lumen contents in which they live; thus, they may be exposed to non-essential elements, such as mercury (Hg), during feeding. The objectives of this study were: 1) determine the total mercury concentrations ([THg]) in Gray wolves (Canis lupus) and their parasites, and 2) use stable isotopes to evaluate the trophic relationships...
Authors
Ashley K. McGrew, Todd M. O’Hara, Craig A. Stricker, Margaret Castellini, Kimberlee B. Beckmen, Mo D. Salman, Lora R. Ballweber
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 CS Hansen, Joseph J. Donovan, Thomas J. Givnish, Craig A. Stricker, John C. Volin
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 A. Stricker, J.E. Mellish, John M. 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
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, Nelio B. Barros, Hasand Gandhi, Craig A. Stricker, Randall S. Wells
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.