Ecological Applications of Stable Isotopes Active
Environmental contaminants of natural and anthropogenic origin represent a major stressor to ecosystems, including human and wildlife populations. FORT scientists are studying these stressors in order to understand the contaminant cycling under natural environmental conditions. Stable isotope techniques are extremely useful in resolving trophic pathways by which contaminants become bioavailable, bioaccumulate, and biomagnify.
Stable isotope geochemistry represents a powerful tool for better understanding biogeochemical cycles, species’ distributions, contaminant cycling, food webs, and ecosystem structure. Using stable isotopes, TSH scientists are able to capitalize on two essential attributes. First, isotopic ratios in an organism’s tissue refl ect the isotopic ratios of what it eats or grows in, and second, local isotopic ratios vary spatially across the face of the earth. Combining this knowledge, our scientists can make inferences into the dietary habits and migration pathways of birds, mammals and fi sh, as well as contaminant cycling and accumulation in species and their habitats. There is a growing need for such information and stable isotopes offer a new approach to integrate earth and life sciences in the context of conservation and environmental change.
The Stable Isotope Laboratory maintained by the Crustal Geophysics and Geochemistry (CGG) and Fort Collins Science Center (FORT) is a state-of-the-art facility with modern instrumentation capable of analyzing the isotopic composition of nearly any conceivable sample matrix. Laboratory staff and principal investigators have significant expertise in isotope systematics of the geosphere, biosphere, and hydrosphere. The Laboratory has demonstrated innovative approaches to challenging questions and as such, has significant latitude to address emerging issues in ecosystem science such as this.
Contaminant Biology: Stable Isotope Applications - Principal Investigator - Craig Stricker
Environmental contaminants of natural and anthropogenic origin represent a major stressor to ecosystems, including human and wildlife populations.
A better mechanistic understanding of contaminant cycling under natural environmental conditions is necessary to mitigate and protect our natural resources. Stable isotope techniques are extremely useful in resolving trophic pathways by which contaminants become bioavailable, bioaccumulate, and biomagnify. The objectives of this project are to:
- Utilize stable isotopes to better resolve the geochemical cycling of contaminants that influences bioavailability.
- Use stable isotope data to constrain contaminant sources.Employ stable isotope techniques to infer trophic transfer pathways of select contaminants.
Biogeochemistry: Stable Isotope Applications - Principal Investigator - Craig Stricker
Biogeochemical cycling is a cornerstone of ecosystem function and structure. Much has been learned about element cycles in a variety of systems using standard geochemical techniques.
Isotope geochemistry can offer unique and additional insights into sources, processes, and mechanisms. Further, many light stable isotope techniques are amenable to studying element cycling, but logically can be extended to consumer organisms and therefore integrate food webs, offering a more complete assessment of ecosystems. Light isotopes commonly used in this context include hydrogen, carbon, nitrogen, oxygen, and sulfur. Further, such techniques can complement studies of related biogeochemical cycles that have proven challenging to study directly with isotopic techniques.
The Stable Isotope Laboratory maintained by the Crustal Geophysics and Geochemistry (CGG) and Fort Collins (FORT)Science Centers is a state-of-the-art facility with modern instrumentation capable of analyzing the isotopic composition of nearly any conceivable sample matrix. Laboratory staff and PI's have significant expertise in isotope systematics of the geosphere, biosphere, and hydrosphere. The Laboratory has demonstrated innovative approaches to challenging questions and as such, has significant latitude to address emerging issues in ecosystem science. In addition, the Laboratory is highly competent in standard mass spectrometric methods and maintains a library of standard operating procedures. The full resources of the Laboratory are available to this Task and relevant research projects.
The objectives of this project are to: employ isotope techniques in tandem with standard geochemistry to better resolve critical biogeochemical processes; to continue to develop sulfur isotope techniques to refine this element cycle, particularly relationships with non-essential metals such as Hg and to couple biogeochemical cycles to food webs through intensive and interdisciplinary place-based studies.
Biogeography: Stable Isotope Applications - Principal Investigator - Craig Stricker
The distribution of species across the landscape is of great interest to conservation biology. Habitat quality and quantity are thought to be important drivers of occurrence and distribution, and numerous studies have demonstrated fitness-related consequences. However, for species with cryptic or migratory life histories, we often lack sufficient detail about habitat usage and in many cases, general location and activity information are unavailable. Extrinsic markers, such as tags and bands, have proven to be rather ineffective due to low returns. Intrinsic markers, such as stable isotopes, on the other hand have great potential because inference is not constrained by recapture. Rather, important insights regarding movement and habitat use can be derived from both metabolically active and inactive tissues of many wildlife species. This approach is cost-effective and has led to important findings regarding the location of wintering and breeding grounds, stop over sites, and the concept of migratory connectivity.
Foraging Ecology Using Stable Isotopes - Principal Investigator - Craig Stricker
Understanding species habitat requirements is incomplete without insight into nutrition, including various aspects of foraging ecology. Traditional diet studies can be challenging because of logistics, issues related to resource availability, and observations are often short-term in nature based on gut contents or scat. Additionally, perturbations such as species introductions, habitat degradation, pollution, and climate change can drastically alter the availability and quality of dietary resources. Stable isotope techniques offer a useful tool for gaining longer-term insight into the dietary habits for a variety of wildlife species.
In collaboration with other USGS scientists, Federal and State agencies, and university researchers, Trust Species and Habitats scientists are using stable isotopes to:
- understand the foraging habits of polar bears, providing context from which future changes because of habitat loss can be inferred;
- investigate nutritional stress as the cause of population decline in Stellar sea lions;
- assess the effects of a gillnet ban on bottlenose dolphin;
- reconstruct aquatic food web pathways before and after exotic species invasions;
- determine the arrival time on arctic breeding grounds of a long-distance migratory shorebird based on a shift in diet; and
- clarify the role of marine-derived nutrients to juvenile salmon. Findings from this work are providing valuable insight into the foraging ecology of species of management or conservation concern.
The Stable Isotope Laboratory maintained by the Crustal Geophysics and Geochemistry (CGG) and Fort Collins Science Center (FORT) is a state-of-the-art facility with modern instrumentation capable of analyzing the isotopic composition of nearly any conceivable sample matrix. Laboratory staff and principal investigators have significant expertise in isotope systematics of the geosphere, biosphere, and hydrosphere. The Laboratory has demonstrated innovative approaches to challenging questions and as such, has significant latitude to address emerging issues in ecosystem science such as this.
Below are other science projects associated with this project.
Contaminant Biology: Stable Isotope Applications
Biogeography: Stable Isotope Applications
Biogeochemistry: Stable Isotope Applications
Foraging Ecology Using Stable Isotopes
Below are publications associated with this project.
Age-specific vibrissae growth rates: a tool for determining the timing of ecologically important events in Steller sea lions
Individual specialization in the foraging habits of female bottlenose dolphins living in a trophically diverse and habitat rich estuary
Stable isotope values in pup vibrissae reveal geographic variation in diets of gestating Steller sea lions Eumetopias jubatus
Improved arrival-date estimates of Arctic-breeding Dunlin (Calidris alpina arcticola)
Unexpected hydrogen isotope variation in oceanic pelagic seabirds
Methylmercury production in sediment from agricultural and non-agricultural wetlands in the Yolo Bypass, California, USA
Selenium and mercury concentrations in harbor seals (Phoca vitulina) from central California: Health implications in an urbanized estuary
Mercury cycling in agricultural and managed wetlands, Yolo Bypass, California: Spatial and seasonal variations in water quality
Mercury cycling in agricultural and managed wetlands: a synthesis of methylmercury production, hydrologic export, and bioaccumulation from an integrated field study
Holocene dynamics of the Florida Everglades with respect to climate, dustfall, and tropical storms
Mercury in gray wolves (Canis lupus) in Alaska: Increased exposure through consumption of marine prey
Seasonal persistence of marine-derived nutrients in south-central Alaskan salmon streams
- Overview
Environmental contaminants of natural and anthropogenic origin represent a major stressor to ecosystems, including human and wildlife populations. FORT scientists are studying these stressors in order to understand the contaminant cycling under natural environmental conditions. Stable isotope techniques are extremely useful in resolving trophic pathways by which contaminants become bioavailable, bioaccumulate, and biomagnify.
Stable isotope geochemistry represents a powerful tool for better understanding biogeochemical cycles, species’ distributions, contaminant cycling, food webs, and ecosystem structure. Using stable isotopes, TSH scientists are able to capitalize on two essential attributes. First, isotopic ratios in an organism’s tissue refl ect the isotopic ratios of what it eats or grows in, and second, local isotopic ratios vary spatially across the face of the earth. Combining this knowledge, our scientists can make inferences into the dietary habits and migration pathways of birds, mammals and fi sh, as well as contaminant cycling and accumulation in species and their habitats. There is a growing need for such information and stable isotopes offer a new approach to integrate earth and life sciences in the context of conservation and environmental change.
The Stable Isotope Laboratory maintained by the Crustal Geophysics and Geochemistry (CGG) and Fort Collins Science Center (FORT) is a state-of-the-art facility with modern instrumentation capable of analyzing the isotopic composition of nearly any conceivable sample matrix. Laboratory staff and principal investigators have significant expertise in isotope systematics of the geosphere, biosphere, and hydrosphere. The Laboratory has demonstrated innovative approaches to challenging questions and as such, has significant latitude to address emerging issues in ecosystem science such as this.
Contaminant Biology: Stable Isotope Applications - Principal Investigator - Craig Stricker
Environmental contaminants of natural and anthropogenic origin represent a major stressor to ecosystems, including human and wildlife populations.
A better mechanistic understanding of contaminant cycling under natural environmental conditions is necessary to mitigate and protect our natural resources. Stable isotope techniques are extremely useful in resolving trophic pathways by which contaminants become bioavailable, bioaccumulate, and biomagnify. The objectives of this project are to:
- Utilize stable isotopes to better resolve the geochemical cycling of contaminants that influences bioavailability.
- Use stable isotope data to constrain contaminant sources.Employ stable isotope techniques to infer trophic transfer pathways of select contaminants.
Sources/Usage: Some content may have restrictions. View Media DetailsBiogeochemistry: Stable Isotope Applications - Principal Investigator - Craig Stricker
Biogeochemical cycling is a cornerstone of ecosystem function and structure. Much has been learned about element cycles in a variety of systems using standard geochemical techniques.
Isotope geochemistry can offer unique and additional insights into sources, processes, and mechanisms. Further, many light stable isotope techniques are amenable to studying element cycling, but logically can be extended to consumer organisms and therefore integrate food webs, offering a more complete assessment of ecosystems. Light isotopes commonly used in this context include hydrogen, carbon, nitrogen, oxygen, and sulfur. Further, such techniques can complement studies of related biogeochemical cycles that have proven challenging to study directly with isotopic techniques.
The Stable Isotope Laboratory maintained by the Crustal Geophysics and Geochemistry (CGG) and Fort Collins (FORT)Science Centers is a state-of-the-art facility with modern instrumentation capable of analyzing the isotopic composition of nearly any conceivable sample matrix. Laboratory staff and PI's have significant expertise in isotope systematics of the geosphere, biosphere, and hydrosphere. The Laboratory has demonstrated innovative approaches to challenging questions and as such, has significant latitude to address emerging issues in ecosystem science. In addition, the Laboratory is highly competent in standard mass spectrometric methods and maintains a library of standard operating procedures. The full resources of the Laboratory are available to this Task and relevant research projects.
The objectives of this project are to: employ isotope techniques in tandem with standard geochemistry to better resolve critical biogeochemical processes; to continue to develop sulfur isotope techniques to refine this element cycle, particularly relationships with non-essential metals such as Hg and to couple biogeochemical cycles to food webs through intensive and interdisciplinary place-based studies.
Sources/Usage: Some content may have restrictions. View Media DetailsBiogeography: Stable Isotope Applications - Principal Investigator - Craig Stricker
The distribution of species across the landscape is of great interest to conservation biology. Habitat quality and quantity are thought to be important drivers of occurrence and distribution, and numerous studies have demonstrated fitness-related consequences. However, for species with cryptic or migratory life histories, we often lack sufficient detail about habitat usage and in many cases, general location and activity information are unavailable. Extrinsic markers, such as tags and bands, have proven to be rather ineffective due to low returns. Intrinsic markers, such as stable isotopes, on the other hand have great potential because inference is not constrained by recapture. Rather, important insights regarding movement and habitat use can be derived from both metabolically active and inactive tissues of many wildlife species. This approach is cost-effective and has led to important findings regarding the location of wintering and breeding grounds, stop over sites, and the concept of migratory connectivity.
Foraging Ecology Using Stable Isotopes - Principal Investigator - Craig Stricker
Understanding species habitat requirements is incomplete without insight into nutrition, including various aspects of foraging ecology. Traditional diet studies can be challenging because of logistics, issues related to resource availability, and observations are often short-term in nature based on gut contents or scat. Additionally, perturbations such as species introductions, habitat degradation, pollution, and climate change can drastically alter the availability and quality of dietary resources. Stable isotope techniques offer a useful tool for gaining longer-term insight into the dietary habits for a variety of wildlife species.
In collaboration with other USGS scientists, Federal and State agencies, and university researchers, Trust Species and Habitats scientists are using stable isotopes to:
- understand the foraging habits of polar bears, providing context from which future changes because of habitat loss can be inferred;
- investigate nutritional stress as the cause of population decline in Stellar sea lions;
- assess the effects of a gillnet ban on bottlenose dolphin;
- reconstruct aquatic food web pathways before and after exotic species invasions;
- determine the arrival time on arctic breeding grounds of a long-distance migratory shorebird based on a shift in diet; and
- clarify the role of marine-derived nutrients to juvenile salmon. Findings from this work are providing valuable insight into the foraging ecology of species of management or conservation concern.
The Stable Isotope Laboratory maintained by the Crustal Geophysics and Geochemistry (CGG) and Fort Collins Science Center (FORT) is a state-of-the-art facility with modern instrumentation capable of analyzing the isotopic composition of nearly any conceivable sample matrix. Laboratory staff and principal investigators have significant expertise in isotope systematics of the geosphere, biosphere, and hydrosphere. The Laboratory has demonstrated innovative approaches to challenging questions and as such, has significant latitude to address emerging issues in ecosystem science such as this.
- Science
Below are other science projects associated with this project.
Contaminant Biology: Stable Isotope Applications
Environmental contaminants of natural and anthropogenic origin represent a major stressor to ecosystems, including human and wildlife populations.Biogeography: Stable Isotope Applications
The distribution of species across the landscape is of great interest to conservation biology. Habitat quality and quantity are thought to be important drivers of occurrence and distribution, and numerous studies have demonstrated fitness-related consequences. However, for species with cryptic or migratory life histories, we often lack sufficient detail about habitat usage and in many cases...Biogeochemistry: Stable Isotope Applications
Biogeochemical cycling is a cornerstone of ecosystem function and structure. Much has been learned about element cycles in a variety of systems using standard geochemical techniques.Foraging Ecology Using Stable Isotopes
Understanding species habitat requirements is incomplete without insight into nutrition, including various aspects of foraging ecology. Traditional diet studies can be challenging because of logistics, issues related to resource availability, and observations are often short-term in nature based on gut contents or scat. Additionally, perturbations such as species introductions, habitat degradation... - Publications
Below are publications associated with this project.
Filter Total Items: 21Age-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 methods to esAuthorsL.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. PitcherIndividual 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 and allowAuthorsSam Rossman, Peggy H. Ostrom, Megan Stolen, Nélio B. Barros, Hasand Gandhi, Craig A. Stricker, Randall S. WellsStable 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 populationAuthorsRick D. Scherer, Andrew C. Doll, Lorrie D. Rea, Aaron M. Christ, Craig A. Stricker, Briana Witteveen, Thomas C. Kline, Carolyn M. Kurle, Michael B. WunderImproved 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 individual diet-swAuthorsAndrew C. Doll, Richard B. Lanctot, Craig A. Stricker, Stephen M. Yezerinac, Michael B. WunderUnexpected 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 up the foAuthorsPeggy H. Ostrom, Anne E. Wiley, Sam Rossman, Craig A. Stricker, Helen F. JamesMethylmercury 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 managed (AuthorsMark Marvin-DiPasquale, Lisamarie Windham-Myers, Jennifer L. Agee, Evangelos Kakouros, Le H. Kieu, Jacob A. Fleck, Charles N. Alpers, Craig A. StrickerSelenium 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 TSe:THg moAuthorsElizabeth A. McHuron, James T. Harvey, J. Margaret Castellini, Craig A. Stricker, Todd M. O'HaraMercury cycling in agricultural and managed wetlands, Yolo Bypass, California: Spatial and seasonal variations in water quality
The seasonal and spatial variability of water quality, including mercury species, was evaluated in agricultural and managed, non-agricultural wetlands in the Yolo Bypass Wildlife Area, an area managed for multiple beneficial uses including bird habitat and rice farming. The study was conducted during an 11-month period (June 2007 to April 2008) that included a summer growing season and flooded conAuthorsCharles N. Alpers, Jacob A. Fleck, Mark C. Marvin-DiPasquale, Craig A. Stricker, Mark Stephenson, Howard E. TaylorMercury cycling in agricultural and managed wetlands: a synthesis of methylmercury production, hydrologic export, and bioaccumulation from an integrated field study
With seasonal wetting and drying, and high biological productivity, agricultural wetlands (rice paddies) may enhance the conversion of inorganic mercury (Hg(II)) to methylmercury (MeHg), the more toxic, organic form that biomagnifies through food webs. Yet, the net balance of MeHg sources and sinks in seasonal wetland environments is poorly understood because it requires an annual, integrated asseAuthorsLisamarie Windham-Myers, Jacob A. Fleck, Joshua T. Ackerman, Mark C. Marvin-DiPasquale, Craig A. Stricker, Wesley A. Heim, Philip A.M. Bachand, Collin A. Eagles-Smith, Gary Gill, Mark Stephenson, Charles N. AlpersHolocene dynamics of the Florida Everglades with respect to climate, dustfall, and tropical storms
Aeolian dust is rarely considered an important source for nutrients in large peatlands, which generally develop in moist regions far from the major centers of dust production. As a result, past studies assumed that the Everglades provides a classic example of an originally oligotrophic, P-limited wetland that was subsequently degraded by anthropogenic activities. However, a multiproxy sedimentaryAuthorsPaul H. Glaser, Barbara C. S. Hansen, Joseph J. Donovan, Thomas J. Givnish, Craig A. Stricker, John C. VolinMercury in gray wolves (Canis lupus) in Alaska: Increased exposure through consumption of marine prey
Mercury (Hg) bioaccumulates in the tissues of organismsand biomagnifies within food-webs. Graywolves (Canis lupus) in Alaska primarily acquire Hg through diet; therefore, comparing the extent of Hg exposure inwolves, in conjunction with stable isotopes, from interior and coastal regions of Alaska offers important insight into their feeding ecology. Liver, kidney, and skeletal muscle samples fromAuthorsAshley K. McGrew, Lora R. Ballweber, Sara K. Moses, Craig A. Stricker, Kimberlee B. Beckmen, Mo D. Salman, Todd M. O’HaraSeasonal persistence of marine-derived nutrients in south-central Alaskan salmon streams
Spawning salmon deliver annual pulses of marine-derived nutrients (MDN) to riverine ecosystems around the Pacific Rim, leading to increased growth and condition in aquatic and riparian biota. The influence of pulsed resources may last for extended periods of time when recipient food webs have effective storage mechanisms, yet few studies have tracked the seasonal persistence of MDN. With this as oAuthorsDaniel J. Rinella, Mark S. Wipfi, Coowe M. Walker, Craig A. Stricker, Ron A. Heintz