2023 Early Hearing Detection & Intervention Conference

March 5-7, 2023 • Cincinnati, OH

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5/20/2019 | 9:30 AM - 9:45 AM | INTERACTIVE EFFECTS OF TEMPERATURE AND NUTRIENT SUPPLY ON STREAM ECOSYSTEM METABOLISM | 150 DEF

INTERACTIVE EFFECTS OF TEMPERATURE AND NUTRIENT SUPPLY ON STREAM ECOSYSTEM METABOLISM

Stream ecosystem responses to climate warming must be considered in the context of other drivers of global change, such as nutrient enrichment. We quantified ecosystem metabolism during three summers (May-August) in four Icelandic streams that varied in mean temperature (8-16°C), before and after whole-stream nutrient additions (Year 1: no enrichment; Year 2: ~200 µg/L PO4-P; Year 3: ~200 µg/L NH4+-N+NO3-N). We predicted that addition of N, but not P, would modify temperature effects on the relative balance of gross primary production (GPP) and ecosystem respiration (ER; i.e., net ecosystem production, NEP). Nitrogen addition led to elevated GPP and ER, and the magnitude of response was positively related to temperature. In addition, N enrichment reduced NEP, particularly for warm streams, shifting their metabolic balance from net carbon sink to source. Addition of P had little effect on GPP but strong effects on ER, while again reducing NEP. Our results demonstrate that nutrient supply is critical in shaping metabolic responses to warming, and that ignoring temperature-nutrient interactions can lead to spurious conclusions about the effects of climate warming on streams.

Multi-stressors
Metabolism
Primary Production

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Presenters/Authors

Wyatt Cross (), Montana State University, wyatt.cross@montana.edu ;