Archaea and Bacteria in deep lake hypolimnion: in situ dark inorganic carbon uptake
The interest for microorganisms inhabiting the hypolimnion and for their role in biogeochemical cycles of lakes is considerable, but knowledge is far from complete. The presence of chemolithoautotrophic Bacteria and mesophilic Archaea (<em>e.g.</em>, Thaumarchaeota) assimilating inorgani...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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PAGEPress Publications
2014-02-01
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| Series: | Journal of Limnology |
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| Online Access: | http://www.jlimnol.it/index.php/jlimnol/article/view/937 |
| _version_ | 1818382919318634496 |
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| author | Cristiana Callieri Manuela Coci Ester M. Eckert Michaela M. Salcher Roberto Bertoni |
| author_facet | Cristiana Callieri Manuela Coci Ester M. Eckert Michaela M. Salcher Roberto Bertoni |
| author_sort | Cristiana Callieri |
| collection | DOAJ |
| description | The interest for microorganisms inhabiting the hypolimnion and for their role in biogeochemical cycles of lakes is considerable, but knowledge is far from complete. The presence of chemolithoautotrophic Bacteria and mesophilic Archaea (<em>e.g.</em>, Thaumarchaeota) assimilating inorganic carbon in the deep hypolimnion of lakes has been ascertained. We measured, for the first time at 350 m in Lake Maggiore (Northern Italy), the prokaryotic <em>in situ</em> dark [14C]HCO3 incorporation with a new custom-made apparatus, which takes samples and adds tracers <em>in situ</em>. Thereby stress factors affecting prokaryotes during sample recovery from the depth were avoided. We tested the new instrument at different depths and conditions, performing parallel conventional on board incubations. We found that dark [14C]HCO3 incorporations had lower standard deviation in <em>in situ</em> incubations with respect to the on board ones, but their means were not statistically different. At 350 m we estimated an uptake of 187.7±15 μg C m–3 d–1, which is in line with the published uptake rates in aquatic systems. By inhibiting the bacterial metabolism, we found that Archaea were responsible for 28% of the total CO2 uptake. At the same depth, Thaumarchaeota, on average, constituted 11% of total DAPI counts. Dark [14C]HCO3 incorporation integrated along the aphotic water column was 65.8±5.2 mg C m–2 d–1 which corresponds to 87% of picophytoplanktonic autotrophic fixation in the euphotic layer. This study provides the first evidence of Bacteria and Archaea dark CO2 fixation in the deep hypolimnion of a subalpine lake and indicates a potentially significant prokaryotic CO2 sink. |
| first_indexed | 2024-12-14T02:58:07Z |
| format | Article |
| id | doaj.art-4f809229cd6f448a91bb6baa4aade71f |
| institution | Directory Open Access Journal |
| issn | 1129-5767 1723-8633 |
| language | English |
| last_indexed | 2024-12-14T02:58:07Z |
| publishDate | 2014-02-01 |
| publisher | PAGEPress Publications |
| record_format | Article |
| series | Journal of Limnology |
| spelling | doaj.art-4f809229cd6f448a91bb6baa4aade71f2022-12-21T23:19:34ZengPAGEPress PublicationsJournal of Limnology1129-57671723-86332014-02-0173110.4081/jlimnol.2014.937603Archaea and Bacteria in deep lake hypolimnion: in situ dark inorganic carbon uptakeCristiana Callieri0Manuela Coci1Ester M. Eckert2Michaela M. Salcher3Roberto Bertoni4CNR - Institute of Ecosystem StudyCNR - Institute of Ecosystem StudyUniversity of ZurichUniversity of ZurichCNR - Institute of Ecosystem StudyThe interest for microorganisms inhabiting the hypolimnion and for their role in biogeochemical cycles of lakes is considerable, but knowledge is far from complete. The presence of chemolithoautotrophic Bacteria and mesophilic Archaea (<em>e.g.</em>, Thaumarchaeota) assimilating inorganic carbon in the deep hypolimnion of lakes has been ascertained. We measured, for the first time at 350 m in Lake Maggiore (Northern Italy), the prokaryotic <em>in situ</em> dark [14C]HCO3 incorporation with a new custom-made apparatus, which takes samples and adds tracers <em>in situ</em>. Thereby stress factors affecting prokaryotes during sample recovery from the depth were avoided. We tested the new instrument at different depths and conditions, performing parallel conventional on board incubations. We found that dark [14C]HCO3 incorporations had lower standard deviation in <em>in situ</em> incubations with respect to the on board ones, but their means were not statistically different. At 350 m we estimated an uptake of 187.7±15 μg C m–3 d–1, which is in line with the published uptake rates in aquatic systems. By inhibiting the bacterial metabolism, we found that Archaea were responsible for 28% of the total CO2 uptake. At the same depth, Thaumarchaeota, on average, constituted 11% of total DAPI counts. Dark [14C]HCO3 incorporation integrated along the aphotic water column was 65.8±5.2 mg C m–2 d–1 which corresponds to 87% of picophytoplanktonic autotrophic fixation in the euphotic layer. This study provides the first evidence of Bacteria and Archaea dark CO2 fixation in the deep hypolimnion of a subalpine lake and indicates a potentially significant prokaryotic CO2 sink.http://www.jlimnol.it/index.php/jlimnol/article/view/937Archaea and Bacteria, Thaumarchaeota, dark inorganic carbon uptake, lake Maggiore, hypolimnion |
| spellingShingle | Cristiana Callieri Manuela Coci Ester M. Eckert Michaela M. Salcher Roberto Bertoni Archaea and Bacteria in deep lake hypolimnion: in situ dark inorganic carbon uptake Journal of Limnology Archaea and Bacteria, Thaumarchaeota, dark inorganic carbon uptake, lake Maggiore, hypolimnion |
| title | Archaea and Bacteria in deep lake hypolimnion: in situ dark inorganic carbon uptake |
| title_full | Archaea and Bacteria in deep lake hypolimnion: in situ dark inorganic carbon uptake |
| title_fullStr | Archaea and Bacteria in deep lake hypolimnion: in situ dark inorganic carbon uptake |
| title_full_unstemmed | Archaea and Bacteria in deep lake hypolimnion: in situ dark inorganic carbon uptake |
| title_short | Archaea and Bacteria in deep lake hypolimnion: in situ dark inorganic carbon uptake |
| title_sort | archaea and bacteria in deep lake hypolimnion in situ dark inorganic carbon uptake |
| topic | Archaea and Bacteria, Thaumarchaeota, dark inorganic carbon uptake, lake Maggiore, hypolimnion |
| url | http://www.jlimnol.it/index.php/jlimnol/article/view/937 |
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