First report on the colony-forming freshwater ciliate Ophrydium versatile in an African river

摘要

CSIR Natural Resources and the Environment, PO Box 395, Pretoria 0001, South Africa;CSIR Natural Resources and the Environment, PO Box 395, Pretoria 0001, South Africa;Department of Zoology, Biological Institute, Universitat Stuttgart, Stuttgart, Germany;Department of Genetics, Stellenbosch University, Matieland 7601, South Africa;%Ophrydium versatile (Muller 1786) Ehrenberg 1830 - a symbiotic ciliate that forms gelatinous colonies - is widely distributed in temperate lakes in Europe and America, but has not previously been recorded from rivers. In this paper we report the first record of O. versatile in an African river, based on an identity confirmed by molecular taxonomic identification. The limnological conditions within the Lephalala River during the sampling period were characterised as oligotrophic with low DOC concentrations, similar to the conditions observed in temperate northern hemisphere lakes where these organisms have been recorded previously. The majority of O. versatile colonies occurred in areas where thin orange-coloured films containing high concentrations of iron (> 60% Fe) covered the substrate and bedrock of the river; this may be related to the abundant picophytoplankton that were associated with these films and oligotrophic conditions. The planktonic diatom Gomphonema venusta Passy was dominant in the water column throughout the study period and acted as an environmental indicator of low electrical conductivity (EC) conditions in the habitat where O. versatile colonies were recorded.