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Dynamics of natural prokaryotes, viruses and heterotrophic nanoflagellates inalpine karstic groundwater

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Wilhartitz Inés, Brussaard Corina, Kirschner Alexander, Stadler Hermann, Fischer Ulrike, Wieltschnik Claudia, Farnleitner Andreas,
Project Microbial communities inherent to karstic aquifers - ecological driving forces in the depth
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Original article (peer-reviewed)

Journal MicrobiologyOpen
Title of proceedings MicrobiologyOpen

Open Access

Type of Open Access Publisher (Gold Open Access)


Seasonal dynamics of naturally occurring prokaryotes, viruses and heterotrophic nanoflagellates in two hydro-geologically contrasting alpine karst springs were monitored over three annual cycles. To our knowledge, this study is the first to shed light on the occurrence and possible interrelationships between these three groups in karstic groundwater. Hydrological and microbiological standard indicators were recovered simultaneously in order to estimate surface influence, especially during rainfall events. Data revealed a strong dependence of the microbial communities on the prevailing hydrological situation. Prokariotic numbers averaged 5.1 × 107 and 1.3 × 107 cells L-1, and heterotrophic nanoflagellate abundance averaged 1.1 × 104 and 3 × 103 cells L-1 in the limestone spring type (LKAS2) and the dolomitic spring type (DKAS1), respectively. Viral abundance in LKAS2 and DKAS1 averaged 9.4 × 108 and 1.1 × 108 viruses L-1. Unlike in DKAS1, the dynamic spring type LKAS2 revealed a clear difference between base flow and high discharge conditions. The virus to prokaryotes ratio was generally lower by a factor of 2 to 3, at higher average water residence times. Furthermore, the high prokaryotes to heterotrophic nanoflagellate ratios, namely about 4700 and 5400 for LKAS2 and DKAS1 respectively, pointed towards an uncoupling of these two groups in the planktonic fraction of alpine karstic aquifers.