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Monday, January 29 • 4:40pm - 5:00pm
WALLEYE: Differential Effects of Algal and Sedimentary Turbidity on the Visual Systems of Walleye (Sander vitreus) and Their Prey

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AUTHORS. Chelsey Nieman, Andy Oppliger, Caroline McElwain; Suzanne M. Gray - The Ohio State University

ABSTRACT. Changes to the visual environment from increased turbidity are expected to result in disrupted visual ecology and are hypothesized to lead to community-level shifts; however, the proximate mechanisms underlying such shifts remain to be investigated. Our objective was to determine the effects of elevated turbidity on visual ecology of native Lake Erie fishes. Turbidity influences visual abilities differently within and across trophic levels (e.g., planktivores vs. piscivores) and across different types of turbidity (e.g., algal vs. sedimentary). We therefore analyzed whether increased turbidity results in reduced detection thresholds and visual acuity in two Lake Erie fishes: a forage fish, Emerald Shiner (Notropis atherinoides), and a top predator, Walleye (Sander vitreus). Utilizing the optokinetic response, we found visual sensitivity in Emerald Shiner (n=17) and Walleye (n=6) was higher in sedimentary (mean=79.66 NTU and 99.98 NTU, respectively) than in algal (mean=34.41 NTU, and 40.35 NTU, respectively) turbidity. Reaction distance experiments that test visual acuity suggest Emerald Shiner (n=40) and Walleye (n=14) display decreased reaction distance in turbid relative to clear water treatments. Our study provides evidence for decreased visual thresholds and acuity as potential mechanisms behind fish responses to increased turbidity.

Monday January 29, 2018 4:40pm - 5:00pm CST