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Presented at the NABS Annual meeting, Vancouver, British Columbia, 2004
in New Directions in Food Web Analysis 1
Stable hydrogen isotopes in freshwater fisheries research
R.R. Doucett1, J.P. Shannon1, M.F. Caron2, G.A. Haden1, and B.A. Hungate1. 1Department of Biology, Northern Arizona University, Flagstaff, Arizona, 86001, 2Grand Canyon Monitoring and Research Center, U.S. Geological Survey, Flagstaff, Arizona, 86001
Recent advances in mass spectrometry have now made the analysis of stable isotopes of hydrogen more accessible and economical to ecologists. Isotopes of hydrogen (D/H) in the environment are strongly associated with the water cycle. For this reason, ecologists can use D/H isotopes to address questions (e.g., water-use by plants, bird migration, etc.) not easily resolved by isotopes of carbon, nitrogen, or sulfur. Here, we report some of the first D/H isotope data to be used in fisheries research. In northern Arizona, intense evaporation, seasonal mixing, and thermal stratification in Lake Powell can alter the D/H isotope value of water released into the Colorado River downstream of Glen Canyon Dam. Fish-tissue collected from the Colorado River and some of its tributaries in the vicinity of Grand Canyon National Park will show that fishes resident to the colder mainstem are isotopically distinct from those in the warmer, free-flowing tributaries. A secondary objective will be to determine if the endangered humpback chub (native to the tributaries) is preyed upon by non-native trout inhabiting the mainstem. It is our hope that stable isotopes of hydrogen will prove to have tremendous potential in fisheries ecology because of their ability to identify river-of-origin in fish.
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