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 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
Stable carbon and nitrogen isotope trophic enrichment factors for Steller sea lion vibrissae relative to milk and fish/invertebrate diets
Improved arrival-date estimates of Arctic-breeding Dunlin (Calidris alpina arcticola)
Unexpected hydrogen isotope variation in oceanic pelagic seabirds
Seasonal persistence of marine-derived nutrients in south-central Alaskan salmon streams
Retrospective analysis of bottlenose dolphin foraging: a legacy of anthropogenic ecosystem disturbance
Effects of trophic level and metamorphosis on discrimination of hydrogen isotopes in a plant-herbivore system
Isotope and Chemical Methods in Support of the U.S. Geological Survey Science Strategy, 2003-2008
Discrimination of carbon and nitrogen isotopes from milk to serum and vibrissae in Alaska Steller sea lions (Eumetopias jubatus)
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 publications associated with this project.