2023 Early Hearing Detection & Intervention Conference

March 5-7, 2023 • Cincinnati, OH

5/21/2019 | 12:15 PM - 12:30 PM | NOVEL INSIGHTS INTO ECOSYSTEM DRIVERS FROM ANALYSIS OF METABOLIC REGIMES | 251 DE

NOVEL INSIGHTS INTO ECOSYSTEM DRIVERS FROM ANALYSIS OF METABOLIC REGIMES

Reservoirs can act as hotspots of biogeochemical activity, modifying downriver nutrient regimes and potentially impacting downriver metabolic regimes and aquatic ecosystems. Here, we show that seasonal and inter-annual variation in phosphorus loading from Lake Powell Reservoir is an important control on Colorado River food webs downriver from Glen Canyon Dam. Variation in phosphorous loading and light are equally important in explaining variation in gross primary production 120 river km below the dam. Invertebrate drift and native fish condition have tracked long-term variation in GPP and a depressed carbon supply likely led to a ~50% decline in the spawning rate of endangered humpback chub in one year. In the tailwater of the dam, invertebrate drift and rainbow trout recruitment also track interannual and seasonal variation in phosphorous loading, however, links to the metabolic regime are not as clear. This discrepancy may result from the more complex aquatic vegetation community located near the dam, which includes rooted macrophytes. Our work highlights how studying metabolic regimes can improve understanding of ecosystem drivers, identifying environmental controls in regulated rivers beyond the usual suspects of temperature, hydrology, and sediment regimes.

Food Webs
Metabolism
Phosphorous

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Presenters/Authors

Charles Yackulic (), USGS Southwest Biological Science Center, Grand Canyon Monitoring and Research Center, cyackulic@usgs.gov;