Gut content analyses
Gut content was quantified from the entire gut of the minnows using a
dissecting microscope. Gut fullness was estimated (5 categories) and
used to weight the volume proportion (equivalent to area proportion at
uniform width) of each prey category observed in the sample which was
estimated to the nearest 5 %. Food items were classified as a)
zooplankton (Cladocera (Eurycercus sp., Bosmina sp.,Daphnia sp., Alona sp., Ceriodaphnia sp.,Leptodora sp., Chydorus sp.), and Ostracoda, b) benthic
invertebrates (Amphipoda, Chironomidae, Ephemeroptera, Nematoda,
Trichoptera, Bivalvia, Gastropoda, Coleoptera, Odonata, Arachnida,
Oligochaeta, Polychaeta), c) terrestrial insects (adult Diptera), and d)
unidentified items and mucus.