2023 Early Hearing Detection & Intervention Conference

March 5-7, 2023 • Cincinnati, OH

5/23/2019 | 9:00 AM - 9:15 AM | BOTTOM-UP EFFECTS OF LAKE TROUT SUPPRESSION IN YELLOWSTONE LAKE | 250 DE

BOTTOM-UP EFFECTS OF LAKE TROUT SUPPRESSION IN YELLOWSTONE LAKE

Lake Trout (Salvelinus namaycush) were introduced into Yellowstone Lake, Wyoming causing a 90% decline in the native Yellowstone Cutthroat Trout (Oncorhynchus clarkii bouvieri) population. In addition to gillnetting, the National Park Service investigated alternative suppression to target the embryos of Lake Trout, including depositing Lake Trout carcasses on spawning sites causing embryo mortality from low dissolved oxygen concentrations, but the effects on nutrient cycling and the foodweb are unknown. We analyzed water samples for nutrients, algae and invertebrates for 15N, and measured ammonium uptake rate by algae throughout the open water season to investigate the degree to which carcasses altered nutrient cycling and these nutrients moved through the foodweb. Ammonium concentrations were 4x higher compared to previous data indicating mineralization of carcasses. Chlorophyll a concentrations increased following carcass deposition indicating increased algae biomass. Isotope samples are currently being analyzed. We expect that 15N from carcasses will be incorporated into algae and invertebrates quickly. Additionally, we predict phytoplankton and periphyton will take up more nitrogen after carcasses were deposited. Understanding how carcass deposition alters the foodweb will help managers understand the effectiveness of alternative suppression and subsequent effects on the ecosystem.

Nitrogen
Zooplankton
Nutrients

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Presenters/Authors

Dominique Lujan (), University of Wyoming, dlujan1@uwyo.edu;