2022 Early Hearing Detection & Intervention Virtual Conference

March 13 - 15, 2022

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5/20/2019 | 9:00 AM - 9:15 AM | DETECTING DIFFERENCES IN NITROGEN FLOW IN ECOSYSTEM-SCALE EXPERIMENTS: A NEW APPROACH TO MODELING ISOTOPE TRACER ADDITIONS IN STREAM ECOSYSTEMS | 250 AB

DETECTING DIFFERENCES IN NITROGEN FLOW IN ECOSYSTEM-SCALE EXPERIMENTS: A NEW APPROACH TO MODELING ISOTOPE TRACER ADDITIONS IN STREAM ECOSYSTEMS

Isotope tracer additions are a powerful tool for estimating nutrient flows in stream ecosystems. To date, these studies have been descriptive in nature and have estimated trophic fluxes using simple models in a piecemeal approach. A successful analytical framework needs to be able to provide flux estimates and associated errors that account for the interdependence of parameter estimates among all compartments, the uncertainty in the diet of consumers, and the over-enrichment of compartments that feed selectively. Here, we present a new, holistic modeling approach based on Bayesian Hidden Markov Models, for the analysis of 15N-NH4+ tracer data in 2 Trinidadian streams in which light and fish populations were experimentally manipulated. This modeling approach allows estimation of uncertainty associated with all N fluxes, propagates error when estimating derived parameters, quantitatively compares alternative models of food web structure, and statistically compares parameter estimates across experimental treatments. We also compare the results of this new approach with estimates derived from historical techniques. This method enables rigorous statistical estimation of nutrient fluxes and ecosystem properties and thus provides a powerful new tool for assessing how whole-stream, experimental manipulations effect food web structure and function.

Food Webs
Isotope
Modeling

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Presenters/Authors

Steven Thomas (), School of Natural Resources, University of Nebraska-Lincoln, Lincoln, sthomas5@unl.edu;