Fatty Acid Profiles of Major Prey and Predator Fish in Lake Ontario: Use in Assessing Food Web Interactions

Abstract

Fatty acid signatures (FAS) are currently used in food web studies to assess trophic interactions between predator and prey. In this study, three major prey fish (alewife, rainbow smelt, and round goby) were collected at three sites along the south shore of Lake Ontario (Olcott, Rochester, and Oswego) during the spring and fall of 2013. Major predator species (including lake trout, brown trout, Chinook salmon, coho salmon, chain pickerel, northern pike, yellow perch, and walleye) were collected along the south shore of Lake Ontario during the summer of 2013. Using multivariate statistics, FAS were compared among all predator and prey species as well as among location and between seasons for prey fish. Though notable seasonal differences were found in alewife FAS, differences in FAS among prey species were greater than any spatio-temporal differences detected within a single species. FAS among predator species were also significantly different though results were consistent with predator taxonomic family. Differentiating fatty acids were similar in among-species comparisons of prey and predator, respectively. Alewife and salmonids were differentiated by oleic acid (18:1n-9), round goby and percids by palmitoleic acid (16:1n-7), and rainbow smelt and esocids by DHA (22:6n-3). FAS suggested a prominent diet of alewife for salmonids and a round goby-rich diet for yellow perch while other species seemed to have a more balanced diet. Our results provide the first comprehensive FAS dataset for major prey and predator species in Lake Ontario. Though specific predator-prey FAS assimilation responses must first be investigated through controlled feeding experiments, the strong heterogeneity among FAS of Lake Ontario prey items suggests that the application of quantitative fatty acid signature analysis (QFASA) is a viable option for assessing predator feeding habits.