title: Occurrence of bacterivory in Cryptomonas, a common freshwater phytoplankter.
abstract: Bacterivory was detected by incorporation of 0.57 μm diameter, fluorescent polystyrene beads and fluorescently labeled bacteria (FLB) in two cultured species of Cryptomonas (C. ovata and C. erosa), and a population of Cryptomonas sp in a humic, mesotrophic lake. Rates of ingestion and clearance were very low, and similar for the cultures and the in situ population. The in situ population incorporated 0.7-1.7 bacteria cell-1h-1, thereby ingesting 0.3%-2.0% of the total bacterial numbers present in the water per day, and receiving less than 2% of its carbon content per day through bacterivory. Thus, bacterivory by Cryptomonas was quantitatively important neither as a sink for bacterial biomass, nor as a carbon source for the algal cells. Possibly, it served in the uptake of essential nutrients.
authors.affiliation: Institute of Ecology, Limnology, University of Lund, Box 65, S-221 00, Lund, Sweden.
authors.forename: Lars J
authors.initials: LJ
authors.lastname: Tranvik
authors.affiliation: Zoology Department, University of Georgia, 30602, Athens, GA, USA.
authors.forename: Karen G
authors.initials: KG
authors.lastname: Porter
authors.affiliation: Graduate School of Oceanography, University of Rhode Island, Narragansett Bay Campus, 02882, Narragansett, RI, USA.
authors.forename: John McN
authors.initials: JM
authors.lastname: Sieburth
keywords: Bacterivory; Cryptomonas; Mixotrophy; Phagotrophy; Plankton