Meeting Abstract

P2.127  Sunday, Jan. 5 15:30  Digestive physiology varies among prickleback fishes (Stichaeidae) with different diets and evolutionary histories GERMAN, DP*; SUNG, A; JHAVERI, PK; AGNIHOTRI, R; Univ. of California, Irvine; Univ. of California, Irvine; Univ. of California, Irvine; Univ. of California, Irvine dgerman@uci.edu

The digestive physiology of an animal can reveal the strategy that an animal takes to acquire resources from their food. In this study we examined how the activity levels of carbohydrases, proteases, and lipase change along the guts of five closely related prickleback fish species with different diets: Cebidichthys violaceus (herbivore), Xiphister mucosus (herbivore), X. atropurpureus (omnivore), Phytichthys chirus (omnivore), and Anoplarchus purpurescens (carnivore). Digestive enzyme activities were measured in the pyloric caeca (which include pancreatic tissue in pricklebacks), and in the proximal, mid, and distal intestines of the fishes. Analyses are in progress, but all five species showed decreasing amylase activity moving distally along the intestine, whereas disaccharidase activities tended to peak in the mid intestines of the herbivores and omnivores, and decrease moving distally along the intestine of the carnivorous A. purpurescens. Measurements of short chain fatty acid concentrations (i.e., indicators of microbial fermentation) in the fishes’ guts are in progress. Overall, the patterns of enzymatic activities are consistent with the “plug-flow reactor” model of digestion, and any reliance on microbial endosymbionts in the digestive process remains to be determined. Enzyme activity patterns (including proteolytic and lipolytic activities) will be discussed in the context of the fishes’ feeding ecology and evolutionary history. In conclusion, this study is unique in its inclusion of closely related fishes with different diets, and lays the foundation for more detailed studies of nutritional physiology in the Stichaeidae.