AME 29:19-28 (2002)  -  doi:10.3354/ame029019

Flow microenvironment of two marine peritrich ciliates with ectobiotic chemoautotrophic bacteria

Kay Vopel1,*, Christian H. Reick1, Günter Arlt2, Martina Pöhn3, Jörg A. Ott3

1Alfred Wegener Institute for Polar and Marine Research, Columbusstr. , 27568 Bremerhaven, Germany
2Institute for Aquatic Ecology, Marine Biology, University of Rostock, Freiligrathstr. 7/8, 18051 Rostock, Germany
3Department of Marine Biology, Institute of Ecology and Conservation Biology, University of Vienna, Althanstr. 14, 1090 Vienna, Austria
*Present address: Department of Oceanography, Florida State University, Tallahassee, Florida 32306-4320, USA. E-mail:

ABSTRACT: The flow microenvironment of 2 marine peritrich ciliates, Vorticella sp. and Zoothamnium niveum, with ectobiotic sulfur bacteria was studied with frame-by-frame analyses of video sequences and a microsensor for fluid velocity. Both species populate the chemocline above H2S-releasing mangrove peat. Vorticella sp. moves the surrounding seawater up to a horizontal and vertical distance of at least 400 μm with a maximum flow velocity of 18 mm s-1 close to its peristomial edge. The feather-shaped colonies of Z. niveum generate a unidirectional flow of seawater passing the colony perpendicular to the stalk; the convex side of the feather faces upstream. The flow velocity increased exponentially towards the colony, up to 11 mm s-1 at a distance of 100 μm. Contraction of the stalk forces the zooids of Vorticella sp. and Z. niveum towards the substrate at a high velocity of 71 and 520 mm s-1, respectively. During contraction of Vorticella sp., only little seawater is dragged along towards the surface to which the ciliates are attached whereas the contraction of Z. niveum resulted in a clear increase in the velocity of the seawater both surrounding the colony and above the substrate. Extension of the species proceeds 700 to 1000 times more slowly than contraction, and the surrounding seawater sticks to the cells and therefore is dragged along. The measurements given here support our earlier data indicating the importance of the feeding current for the bacteria-ciliate association, i.e. the cilia beat drives H2S- and O2-containing seawater toward the zooid at high velocity and thus, supports the growth of the ectobiotic sulfide-oxidizing bacteria. Rapid movement, shrinkage (Vorticella sp.) and bunching (Z. niveum) of the zooids during stalk contraction apparently cause sufficient shear stress to abrade ectobiotic bacteria that, once suspended, could enter the feeding currents.

KEY WORDS: Sulfur ectosymbioses · Chemoautotrophic bacteria · Peritrich ciliates · Vorticella · Zoothamnium niveum · Flow velocity

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