Microbial activity under the ice cover of the shallow Neusiedler See (Austria, Central Europe)
- Author(s)
- Bettina Reitner, Alois Herzig, Gerhard J. Herndl
- Abstract
In an attempt to assess bacterioplankton production and growth yield under low temperature conditions and to compare bacterioplankton with phytoplankton productionin the ice-covered water column of the shallow Neusiedler See, outdoor measurements under near in situ conditions were performed during the winter of 1995/96. During the investigation period, mean chlorophyll (Chl) a concentration was 21.03 ± 14.95 μg Chl a l-1. Phytoplankton primary production integrated over the water column ranged from 1.35 to 4.23 mg C m-2 d-1 (mean ± SD = 2.46 ± 1.06 mg C m-2 d-1). Bacterial abundance varied from 20 to 40 × 105 ml-1 for most of the investigation period and increased by the end of March concomitantly with the increase in temperature from 1.3 to 6.3°C within 5 days. Mean bacterial production was 15.3 ± 12.8 μg C l-1 d-1 (range: 3.0 to 41.7 μg C l-1 d-1) and mean bacterial growth rate 0.23 ± 0.16 d-1 following closely the pattern in bacterial production. DOC concentration declined linearly from 20.7 mg C l-1 to 16.45 mg C l-1 over the 4 months period of ice cover. The contribution of humic substances to the total DOC pool declined from 43.6% at the end of November to 37.3% at the end of March. Calculated on an area basis, phytoplankton production amounted to only 16% of bacterial production which makes it unlikely that phytoplankton supply substrate for bacterioplankton growth in significant quantities when the lake is ice covered. From the observed decline in DOC over the investigation period and assuming only negligible input of DOC from other sources we calculated an average DOC uptake by the bacterioplankton community of 47.5 μg C l-1 d-1 resulting in a bacterial growth efficiency of 15.9% for the ice covered conditions. Based on the growth efficiency we estimate that pelagic primary production amounts to 2.8% of the bacterial carbon demand. This might indicate that the bacterioplankton in Neusiedler See sustain their high growth rates at low temperatures (< 2°C for most of the investigation period) by using probably the DOC originating from the previous season. This DOM stems most likely from the decay of the reed Phragmites australis and its epiphytes and, probably of minor importance, from phytoplankton leachates.
- Organisation(s)
- Functional and Evolutionary Ecology
- External organisation(s)
- Biological Station Lake Neusiedl, Royal Netherlands Institute for Sea Research, Universität Wien
- Journal
- Hydrobiologia
- Volume
- 357
- Pages
- 173-184
- No. of pages
- 12
- ISSN
- 0018-8158
- Publication date
- 12-1997
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 106020 Limnology
- Keywords
- ASJC Scopus subject areas
- Aquatic Science
- Portal url
- https://ucris.univie.ac.at/portal/en/publications/microbial-activity-under-the-ice-cover-of-the-shallow-neusiedler-see-austria-central-europe(4fab4079-ddd8-4e14-ae33-c31ae2fcaa30).html