2023 Early Hearing Detection & Intervention Conference

March 5-7, 2023 • Cincinnati, OH

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5/25/2021 | 2:00 PM - 3:30 PM | The decoupling of contaminant pulses by recipient food webs in a major U.S. river | Virtual Platform

The decoupling of contaminant pulses by recipient food webs in a major U.S. river

Hydrologic regimes in rivers mobilize contaminants to aquatic ecosystems and pulsed flows often account for substantial proportions of annual contaminant loading and export from catchments. Though it is commonly assumed that contaminant uptake by recipient food webs is lower in lotic than lentic systems, the timing of contaminant trophodynamics is understudied in rivers. We investigated temporal patterns in selenium mobilization, partitioning, and trophic transfer in the Lower Gunnison River Basin (Colorado, USA), a selenium-impaired ecosystem influenced by the underlying Mancos Shale and irrigation practices. Using analyses of selenium concentrations in ~1,000 surface water, particulate, macroinvertebrate, and fish samples collected between June 2015-October 2016, we show that: (1) temporal patterns in Se partitioning and trophic transfer were independent of surface water concentrations, (2) primary producers can quickly accumulate pulsed contaminants, and (3) that macroinvertebrates may sustain elevated Se concentrations from earlier periods of high Se mobilization. Evidence that periods of high-flow selenium mobilization can have a greater influence on the selenium status of recipient food webs than periods characterized by both longer residence times and higher loading challenges the assumption that contaminant bioaccumulation potential is reduced in lotic systems.

Food webs
Ecological dynamics
Flow regime

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Presenters/Authors

Jessica E. Brandt (), University of Connecticut, jessica.brandt@uconn.edu;