How Trophic Cascades Are Powerful Forces That Have A...

Yellow Perch (Perca flavenscens) Food Chain Dynamics in Lac la Biche, Alberta Proposal Jacob Thalen, Feb, 5, 2015 ThalenJ2@mymacewan.ca MacEwan University, Department of Biology Done in part for the requirements of BIOL 498 under the supervision of Dr. David Locky Dr. Mrinal Das. MacEwan University, Department of Biology. Abstract: Trophic cascades are powerful forces that have a pronounced effect on ecosystems. They occur when predation causes shifts in prey dynamics that indirectly lead to enhanced survival in the next lowest trophic level. Walleye fishing bans at Lac la Biche coinciding with a restocking effort have led to a large recovery of walleye populations. The increase in populations of a high trophic level predator should cause shifts in a lower trophic level species (yellow perch) prey preferences from fish towards invertebrate prey. 576 yellow perch stomach collected from 2009 - 2013 by Alberta Environment and Sustainable Resource Development were sent to MacEwan University for processing/analysis. Yellow perch stomachs will be measured (dry weight, empty weight), and prey items will be removed identified and weighed. Sampling procedure differs depending on the type of prey item removed from the stomach (fish, macro and micro invertebrates). Length and weight measurements will be taken fo r fish and macro invertebrates; whereas, micro invertebrates will be sub sampled until 50-100 individuals can be identified. Data will be analyzed using multi