Grantee Research Project Results
2003 Progress Report: Influence of Bio-Pollution on Ecosystem Processes: The Impact Introduced Lake Trout on Streams and Terrestrial Predators in Yellowstone National Park
EPA Grant Number: R829426E02Title: Influence of Bio-Pollution on Ecosystem Processes: The Impact Introduced Lake Trout on Streams and Terrestrial Predators in Yellowstone National Park
Investigators: Hall, Robert O. , Ben-David, Merav
Institution: University of Wyoming
EPA Project Officer: Chung, Serena
Project Period: July 15, 2002 through September 30, 2004
Project Period Covered by this Report: July 15, 2002 through September 30, 2003
Project Amount: $160,610
RFA: EPSCoR (Experimental Program to Stimulate Competitive Research) (2001) RFA Text | Recipients Lists
Research Category: EPSCoR (The Experimental Program to Stimulate Competitive Research)
Objective:
Invasive species can impact populations and ecosystem processes within the recipient ecosystem, but their impacts outside of this ecosystem are rarely considered. Lake trout (Salvelinus namaycush) have invaded Yellowstone Lake, and if left unchecked, are predicted to substantially lower native cutthroat trout (Oncorhynchus clarki bouvieri) populations. The impact of fewer native cutthroat trout almost certainly will extend beyond the lake to trout-spawning tributary streams. The objective of this research project is to investigate the role of cutthroat trout in structuring stream ecosystems, their importance to river otters (Lontra canadensis), and possible links to terrestrial plants, thus integrating instream and terrestrial processes. For the element cycling component of this research project, we focus on nitrogen (N) because it limits production in streams and terrestrial ecosystems. These observations will enable us to make initial predictions about how streams, trout predators, and the terrestrial landscape will be affected following cutthroat trout demise. Upon completion, this research project will provide insights into potential ecosystem changes in other systems where reductions in anadromous salmonids may occur.
Progress Summary:
The Science and Engineering Environmental Research component of the Wyoming Environmental Protection Agency/Experimental Program to Stimulate Competitive Research (EPA/EPSCoR) Project already has met many of its stated objectives. After recruiting two graduate students (Jamie Crait and Lusha Tronstad) and five undergraduate students (Jessica Boyd, Robert Eddy, Christine Fisher, Kaithryn Ott, and Scott Schaefer) to work on the project, one full field season was conducted for the instream processes component, and two field seasons were completed for the river otter/riparian plants component. In addition, several of the laboratory analyses also were completed for both sections. Other laboratory analyses and additional field seasons for the instream component are planned. For the instream component, 12 streams were surveyed; of which, 3 were sampled intensively. Between 15 and 45 samples of biofilm and invertebrates were collected for isotope analysis, and between 20 and 80 water samples were collected for analyses of ammonium and nitrate concentrations. In addition, more than 130 samples were collected to estimate invertebrate secondary production. Finally, 20 cutthroat trout were captured, and their excretion rates were measured. For the river otter/riparian plants component, more than 250 km of lakeshore and stream banks were surveyed, and 87 otter latrines were found. Two hundred and three fresh feces were collected for DNA analysis, and 989 feces were collected for diet analysis. In addition, nearly 500 samples from 12 different species of plants were collected for stable isotope analysis. Plant species on all latrines and 102 random sites were identified, and the growth of shoots was measured for one species of shrub (Ribes sp.). Increment cores were collected from 25 spruce trees and 18 pine trees for historical reconstruction of cutthroat abundance.
Our preliminary results indicate that recent N transports from lake to streams are significantly lower than historical values with the reductions in cutthroat trout. The effects of such lower N input on instream process are still being evaluated. Otter surveys suggest that although activity levels of river otters in Yellowstone Lake and tributaries are similar to other systems in the intermountain West, the actual abundance of otters may be lower. Otters exhibited a seasonal change in activity patterns in response to the spawning migrations of cutthroat trout. Our stable isotope results support the hypothesis that river otters transport aquatically derived N onto latrine sites, and in turn, fertilize plants at these locations. Effects of such fertilization on plant growth and community composition are still being evaluated. Preliminary results suggest that tree-ring widths alone are not a reliable proxy for temporal changes in cutthroat trout abundance and otter activity. We are currently analyzing tree cores for 15N to relate temporal changes in N isotope values to historical cutthroat populations. Data from Yellowstone National Park, combined with preliminary results from our research project, suggest that a significant decline in cutthroat trout abundance already has occurred, and that such decline may result in changes in the structure of streams, the abundance of otters, and the transport of nutrient to the riparian ecosystem.
Future Activities:
At least two additional field seasons are planned for the instream component of the project. Because a graduate student (Lusha Tronstad) joined that portion of the project in the summer of 2003, additional surveys and sampling will be needed to address the objectives of the study. In addition, analysis of stable isotope ratios for biofilm, invertebrates, trout excretion, and riparian plants collected in 2003 and increment cores of trees are planned for the coming year. Also, completion of diet analysis from river otter scats is expected to continue for several additional months. To meet our goals, we will request a no-cost extension for the project. Two graduate students are preparing three manuscripts for publication and these will be submitted before July 2004. . Data from Yellowstone National Park, combined with preliminary results from our study, suggest that a significant decline in cutthroat trout abundance already has occurred. This decline, in turn, may have already resulted in changes in the structure of streams, the abundance of otters, and the transport of nutrient to the riparian ecosystem. Therefore, continuation of this project is crucial because it will provide insights into potential ecosystem changes in other systems where reductions in anadromous salmonids may occur. We are seeking additional funds to expand and continue this work from a variety of sources such as the U.S. National Park Service, University of Wyoming-National Park Service Research Center, U.S. Geological Survey, U.S. Fish and Wildlife Service, National Science Foundation, and EPA.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 24 publications | 4 publications in selected types | All 4 journal articles |
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Type | Citation | ||
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Crait JR, Ott KE, Ben-David M. Transfer of nutrients from Yellowstone Lake to riparian forests by river otters: effects on plant isotopes, growth, and community composition. Ecology. |
R829426E01 (2003) R829426E02 (2003) |
not available |
Supplemental Keywords:
ecological effects, ecosystem, indicators, terrestrial, aquatic, analytical, surveys, western states, cutthroat trout, invasive species, limnology, nitrogen, N, nutrient transports, river otters, stream invertebrates, tree cores, Yellowstone, Yellowstone Park, anthropogenic processes, anthropogenic stress, aquatic biota, aquatic ecosystems, bioassessment, biodiversity, bioindicators, biological impairment, biological indicators, biopollution, conservation, conservation planning, diagnostic indicators, ecosystem indicators, ecosystem monitoring, ecosystem response, ecosystem stress, lake trout, lakes, land use, nitrogen uptake, nutrient transport, restoration planning, watershed assessment, watershed classification, watershed management, watershed restoration., RFA, Scientific Discipline, INTERNATIONAL COOPERATION, ECOSYSTEMS, Water, Ecosystem Protection/Environmental Exposure & Risk, Aquatic Ecosystems & Estuarine Research, Water & Watershed, Ecology, Ecosystem/Assessment/Indicators, Aquatic Ecosystem, Water Quality Monitoring, Ecological Effects - Environmental Exposure & Risk, Monitoring/Modeling, Terrestrial Ecosystems, Environmental Monitoring, Ecology and Ecosystems, Watersheds, anthropogenic stress, bioassessment, anthropogenic processes, watershed classification, nutrient transport, lake trout, ecosystem monitoring, watershed management, biodiversity, biopollution, Yellowstone Park, conservation, diagnostic indicators, ecosystem indicators, lakes, aquatic ecosystems, bioindicators, watershed sustainablility, invasive species, water quality, biological indicators, ecosystem stress, watershed assessment, conservation planning, nitrogen uptake, ecosystem response, aquatic biota, land use, restoration planning, watershed restorationRelevant Websites:
http://www.uwyo.edu/enr/enrschool.htm Exit
http://www.uwyo.edu/bhall/ Exit
http://uwadmnweb.uwyo.edu/Zoology/faculty/Ben-David/ Exit
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.