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

12 pages, 4 figures, 3 tables 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 analy...

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Bibliographic Details
Published in:Journal of Plankton Research
Main Authors: Gerea, Marina, Queimaliños, Claudia, Schiaffino, M. Romina, Izaguirre, Irina
Format: Article in Journal/Newspaper
Language:English
Published: Oxford University Press 2013
Subjects:
Mixotrophic flagellates
Heterotrophic flagellates
Prey selection
CARD-FISH
Oligotrophic lakes
Antarctic
Argentina
Antarc*
ren
Online Access:http://hdl.handle.net/10261/72356
https://doi.org/10.1093/plankt/fbs085
Description
Summary:12 pages, 4 figures, 3 tables 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 This study was financed by the Consejo Superior de Investigaciones Cientı´ficas – Consejo Nacional de Investigaciones Cientı´ficas y Te´cnicas (CSIC-CONICET) (Spain-Argentina) Project PROBA (2007 AR0018, CSIC), the Spanish Project MIXANTAR (REN 2002-11396-E/ANT) and the Argentinean projects CONICET-PIP 01301, FONCYT PICT 32732 and UNComahue 04/ B166. Marina Gerea and M. Romina Schiaffino were supported by CONICET fellowships. Irina Izaguirre, Claudia Queimalin˜os and Fernando Unrein are CONICET researchers Peer reviewed

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