Abstract
AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 54:35-44 (2009) - DOI: https://doi.org/10.3354/ame01253 Significance of swimming and feeding currents for nutrient uptake in osmotrophic and interception-feeding flagellates V. J. Langlois1,3,*, A. Andersen1, T. Bohr1, A.W. Visser2, T. Kiørboe2 1Department of Physics and Center for Fluid Dynamics, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark 2National Institute for Aquatic Resources, Technical University of Denmark, Kavalergården 6, 2920 Charlottenlund, Denmark 3Present address: Laboratoire de Sciences de la Terre, Université Claude Bernard Lyon 1 –ENS Lyon– C.N.R.S., 2 rue Raphaël Dubois, 69622 Villeurbanne cedex, France *Email: vincent.langlois@univ-lyon1.fr ABSTRACT: We introduce 2 simple models for the flow generated by a self-propelled flagellate: a sphere propelled by a cylindrical flagellum and one propelled by an external point force. We use these models to examine the role of advection in enhancing feeding rates in 3 situations: (1) osmotroph feeding on dissolved molecules, (2) interception feeding on non-motile prey particles, and (3) interception feeding on motile prey (such as bacteria). We show that the Sherwood number is close to unity for osmotrophic flagellates, as suggested by most previous models. However, a more correct representation of the flow field than that predicted by a naive sinking sphere model leads to substantially higher clearance rates for interception-feeding flagellates. We find that a short flagellum is favourable for interception feeding, but at the cost of an increase in the drag on the body of the swimming unicell. We finally demonstrate that prey motility significantly enhances prey encounter rates in interception-feeding flagellates and is, in fact, often much more important for food acquisition than the feeding current. KEY WORDS: Flagellates · Nutrient uptake · Interception feeders · Motile prey Full text in pdf format PreviousNextCite this article as: Langlois VJ, Andersen A, Bohr T, Visser A, Kiørboe T (2009) Significance of swimming and feeding currents for nutrient uptake in osmotrophic and interception-feeding flagellates. Aquat Microb Ecol 54:35-44. https://doi.org/10.3354/ame01253Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 54, No. 1. Online publication date: January 15, 2009 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2009 Inter-Research.
Highlights
Many unicellular planktonic organisms are nonmotile and depend on prey particles to come to them
We use these models to examine the role of advection in enhancing feeding rates in 3 situations: (1) osmotroph feeding on dissolved molecules, (2) interception feeding on non-motile prey particles, and (3) interception feeding on motile prey
This applies to many osmotrophs, such as non-motile pelagic diatoms that depend on nutrient molecules to diffuse to their cell surface before they can be taken up. It applies to some phagotrophic particle feeders, such as radiolarians and helioflagellates that feed on motile prey, e.g. bacteria, that are eaten upon interception by the predator cell body or pseudopodia that extend from the cell body
Summary
Many unicellular planktonic organisms are nonmotile and depend on prey particles (molecules or organisms) to come to them. Flagellates and other motile unicells are not moved by body force; they are self-propelled, i.e. pushed or pulled through the water by one or more beating flagella This implies that streamlines come closer to the surface of the cell than in the case of a sinking cell, and that current models of clearance rates in interception-feeding flagellates and nutrient transport in swimming flagellates underestimate the role of advection. We consider 2 simple models for the flow generated by a self-propelled flagellated microorganism: a sphere propelled either by a cylindrical flagellum or by an external point force We use these models to examine the role of propulsion in enhancing nutrient acquisition in 3 situations: (1) osmotroph feeding on dissolved molecules, (2) interception feeding on non-motile prey particles, and (3) interception feeding on motile prey (such as bacteria). Langlois et al: Nutrient uptake in osmotrophic and interception-feeding flagellates
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