In situ prey selection of mixotrophic and heterotrophic flagellates in Antarctic oligotrophic lakes: An analysis of the digestive vacuole content

We investigated the selective predation of mixotrophic and heterotrophic flagellates (MF and HF) on different heterotrophic prokaryote phylotypes (HPP; Bacteria + Archaea) living in natural assemblages from oligotrophic Antarctic lakes. In situ prey preference was analyzed for the first time on diff...

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Bibliographic Details
Authors: Gerea, M., Queimaliños, C., Schiaffino, M.R., Izaguirre, I., Forn, I., Massana, R., Unrein, F.
Format: article
Status:Published version
Publication Date:2013
Country:Argentina
Institution:Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturales
Repository:Biblioteca Digital (UBA-FCEN)
Language:English
OAI Identifier:paperaa:paper_01427873_v35_n1_p201_Gerea
Online Access:http://hdl.handle.net/20.500.12110/paper_01427873_v35_n1_p201_Gerea
Access Level:Open access
Keyword:CARD-FISH
Heterotrophic flagellates
Mixotrophic flagellates
Oligotrophic lakes
Prey selection
catalysis
digestive system
flagellate
heterotrophy
lake ecosystem
mixotrophy
morphology
oligotrophic environment
phylogenetics
phytoplankton
predation
prey selection
prokaryote
protist
Antarctica
Actinobacteria
Alphaproteobacteria
Archaea
Bacteria (microorganisms)
Bacteroidetes
Betaproteobacteria
Chrysophyceae
Mastigophora (flagellates)
Ochromonas
Prokaryota
Protista
Pseudopedinella
Description
Summary:We investigated the selective predation of mixotrophic and heterotrophic flagellates (MF and HF) on different heterotrophic prokaryote phylotypes (HPP; Bacteria + Archaea) living in natural assemblages from oligotrophic Antarctic lakes. In situ prey preference was analyzed for the first time on different mixotrophic taxa (Pseudopedinella sp., Ochromonas-like cells, Chrysophyceae >5 μm). The relative abundances of seven different HPP hybridized by CARD-FISH (catalyzed reporter deposition-fluorescent in situ hybridization) in natural community were compared with the proportions of hybridized cells inside digestive vacuoles. Our results showed some general trends to selectivity over some HPP. Alphaproteobacteria and Betaproteobacteria were the most abundant groups, and strikingly, a negative selection trend was detected in most samples by all bacterivorous protists. In contrast, for Actinobacteria a positive selection trend was observed in most samples, whereas Bacteroidetes seemed to be randomly preyed upon. Interestingly, similar prey preferences were observed in all bacterivorous flagellates. Our results suggest that phylogenetic affiliation determines part of the process of prey selection by protists in these lakes. Nevertheless, other features, such as cell size, morphology and the presence of the S-layer, might also significantly contribute to prey selectivity on the HPP. © 2012 The Author 2012. Published by Oxford University Press. All rights reserved.

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