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CONFERENCE SCHEDULE UPDATES & CHANGES: As a result of the prolonged government shutdown, we experienced a number of cancellations and changes to the schedule. Cancellations and changes are listed here (as of January 26, 2019). 

Monday, January 28 • 4:20pm - 4:40pm
(SYMPOSIA-04) Energy Pathways to Prey Fishes Across a Productivity Gradient: A Case-study in the Laurentian Great Lakes

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AUTHORS: Anne Scofield, Paris Collingsworth, Tomas Höök – Purdue University; David Bunnell, USGS Great Lakes Science Center; Aaron Fisk, University of Windsor Great Lakes Institute for Environmental Research; Tim Johnson, Ontario Ministry of Natural Resources; Brian Weidel, USGS Lake Ontario Biological Station

ABSTRACT: Natural stable isotope ratios of nitrogen (d<sup>15</sup>N) and carbon (d<sup>13</sup>C) have proven to be valuable tools for identifying basal energy sources for fish production and describing trophic complexity, but cross-lake comparisons of stable isotope data are often limited by challenges associated with standardizing study design and isotopic baselines. Over the past decade, a great number of resources have been invested to generate stable isotope data for the lower food web and prey fishes across all five of the Great Lakes through the bi-national Cooperative Science and Monitoring Initiative (CSMI), providing opportunities for robust cross-lake comparisons. In this study, we investigate differences in nearshore subsidies and trophic transfer efficiencies to prey fish across the productivity gradient observed in the Great Lakes, which range from eutrophic (western Lake Erie) to ultra-oligotrophic (e.g., Lake Superior). Using rainbow smelt as a case study, we examine the basal carbon sources and trophic positions of prey fish in the offshore regions of the five lakes. We also consider how differences in the densities on non-native species, such as dreissenid mussels, may affect resource distribution and energy flow to fishes. Quantifying how trophic structures in lakes differ across a productivity gradient can help elucidate the consequences of human actions such as nutrient management programs, fish stocking, and non-native species introductions.

Monday January 28, 2019 4:20pm - 4:40pm

Attendees (13)