From ceginfo@u.washington.edu Thu Feb 22 14:49:29 2001 Received: from jason01.u.washington.edu (root@jason01.u.washington.edu [140.142.8.10]) by lists.u.washington.edu (8.9.3+UW00.05/8.9.3+UW00.12) with ESMTP id OAA103380 for ; Thu, 22 Feb 2001 14:49:25 -0800 Received: from homer38.u.washington.edu (ceginfo@homer38.u.washington.edu [140.142.16.4]) by jason01.u.washington.edu (8.9.3+UW00.05/8.9.3+UW00.12) with ESMTP id OAA29920; Thu, 22 Feb 2001 14:49:21 -0800 Received: from localhost (ceginfo@localhost) by homer38.u.washington.edu (8.9.3+UW00.05/8.9.3+UW00.12) with ESMTP id OAA22158; Thu, 22 Feb 2001 14:49:19 -0800 Date: Thu, 22 Feb 2001 14:49:18 -0800 (PST) From: Civil and Environmental Engineering To: faculty@ce.washington.edu, cegrads@u.washington.edu, deschind@zoology.washington.edu, tquinn@fish.washington.edu Subject: MS Defense for Ashley Ballantyne - Feb. 28, 2001 Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII The final examination for the Master of Science degree for Ashley Ballantyne will be held on February 28, 2001 at 11:00 in Room 218 More Hall. "The importance of food quality for herbivorous zooplankton and sockeye salmon growth in Lake Washington" Abstract Characterizing food quality for herbivores and carnivores is of critical importance to understanding the processes governing the flow of energy through food webs. Two hypotheses have been proposed to explain food quality- 1.) that imbalances in the relative availability of particular elements between consumers and their food may limit growth; 2.) Essential fatty acids may limit the growth of consumers. Growth rates were measured for the herbivorous zooplanktoner Daphnia pulex fed on phytoplankton from Green Lake, Lake Sammamish and Lake Washington, which were measured for C, P, N, Chlorophyll-a and fatty acid content. Daphnia growth rates were significantly higher in the mesotrophic Lake Washington compared with the other two lakes. In Lake Sammamish, C, N were positively correlated and P:C ratios were negatively correlated with Daphnia growth. In Lake Washington Chlorophyll-a, C, N, P and the essential fatty acid eicosapentaenoic acid (EPA) all showed significant positive relationships with Daphnia growth. These results are confounding to the hypothesis of elemental stoichiometry and provide some support for the essential fatty acid hypothesis. The implications of food quality limitation for sockeye were also tested using a bioenergetics model in conjunction with mass balance models. Zooplankton species composing the diet of Lake Washington sockeye were collected and analyzed for their fatty acid composition. Significant differences were measured in the prey content of the essential fatty acid docosahexaenoic (DHA). Model predictions suggest that sockeye do not experience growth limitation due to the amount of phosphorus or EPA in their diet. However, during the spring and summer they may experience limited growth due to a deficiency in DHA. Despite aggregation at sub-optimal temperatures, food quality and availability appear to be more important than temperature in the limitation of sockeye growth in Lake Washington. Professor Michael T. Brett, Chair Professor Daniel Schindler, Zoology Professor Thomas Quinn, Fisheries Marcia Buck Graduate Advising Office Dept. of Civil & Environmental Engineering University of Washington Box 352700 Seattle, WA 98195-2700 (206) 543-2574 email: ceginfo@u.washington.edu .