Biology Centre CAS 1 article published in JoVE Environment Fluorescently Labeled Bacteria as a Tracer to Reveal Novel Pathways of Organic Carbon Flow in Aquatic Ecosystems Karel Šimek1, Dagmara Sirova1 1Department of Aquatic Microbial Ecology, Institute of Hydrobiology, Biology Centre CAS Presented here is a protocol for a single-cell, epifluorescence microscopy-based technique to quantify grazing rates in aquatic predatory eukaryotes with high precision and taxonomic resolution.