2023 Early Hearing Detection & Intervention Conference

March 5-7, 2023 • Cincinnati, OH

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6/07/2017 | 10:00 AM - 10:15 AM | PHOTOSYNTHESIS, RESPIRATION AND NITROGEN UPTAKE CHARACTERISTICS OF STREAM SUBSTRATA IN TROPICAL STREAMS: HETEROGENEITY AND SCALING | 306B

PHOTOSYNTHESIS, RESPIRATION AND NITROGEN UPTAKE CHARACTERISTICS OF STREAM SUBSTRATA IN TROPICAL STREAMS: HETEROGENEITY AND SCALING

Leaves, epilithon, macrophytes and fine benthic organic material are central to food webs and nutrient fluxes in streams. However, most estimates of gross primary production (GPP) and ecosystem respiration (ER) are taken at a reach-scale, omitting information on how these different compartments contribute to frame whole-stream estimates. We measured substrate-specific GPP and ER and ammonium and nitrate 15N uptake in recirculating chambers, to evaluate autotrophic and heterotrophic contribution to metabolic characteristics. We compared these decimeter-scale measurements to whole-stream estimates concurrently measured in three sites across a river continuum in a preserved Atlantic forest in Brazil. Epilithon and macrophytes (when present) were the dominant GPP and N uptake compartments in open canopy sites, but leaves contributed strongly to ER even though they covered a small percentage of the stream bottom. Ammonium and nitrate uptake was significantly different between substrata and streams with different canopy cover. However, up-scaled results showed that total nitrogen uptake was only different when macrophytes were present and whole-stream uptake estimates were consistent with chambers estimates for ammonium but not for nitrate in the smallest closed canopy stream.

S09 The importance of environmental gradients for the advance of tropical stream ecology
C25 Food Webs
S09 The importance of environmental gradients for the advance of tropical stream ecology

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Presenters/Authors

Flavia Tromboni (), University of Nevada, Reno, ftromboni@unr.edu;