Determining Diets for Fish from Small Central British Columbia Streams: Predator-Prey Analysis Using Morphological and Molecular Approaches

Dietary analysis was used to assess predator-prey relationships and help reveal dynamics of ecosystem function within small central British Columbia streams. Diet analysis on fish has traditionally been completed through morphological identification of the stomach contents, but this approach presents bias towards the hard-bodied species whose characteristics can be detected. This problem is further confounded in species whose diet is dominated by invertebrates, as prey items are generally very small and taxonomically diverse. Molecular techniques allowed us to increase efficiency and accuracy of identification, and reduce biases. To assess diet of stream fishes and help understand predator prey dynamics, we analyzed stomach contents of prickly sculpins, rainbow trout and cutthroat trout using traditional taxonomic methods and also using next-generation sequencing (NGS). Recognizable prey items were morphologically identified to the lowest possible taxonomic level and DNA was extracted from each item individually. These individual extractions were analyzed on an Ion Torrent platform along with bulk samples of all remaining fragments from the fish stomachs, to determine the effectiveness of NGS at providing a complete picture of diet for each fish and community dynamics within lotic environments.