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DatoValore
TitleArchaea and Bacteria in deep lake hypolimnion: in situ dark inorganic carbon uptake
AbstractThe 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 (e. g., 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 in situ dark [C-14]HCO3 incorporation with a new custom-made apparatus, which takes samples and adds tracers in situ. 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 [C-14] HCO3 incorporations had lower standard deviation in in situ 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 mu g 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 [C-14]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.
SourceJournal of limnology (Testo stamp.) 73 (1), pp. 47–54
KeywordsArchaea and BacteriaThaumarchaeotadark inorganic carbon uptakeLake Maggiorehypolimnion
JournalJournal of limnology (Testo stamp.)
EditorIstituto per lo Studio degli Ecosistemi., Verbania Pallanza, Italia
Year2014
TypeArticolo in rivista
DOI10.4081/jlimnol.2014.937
AuthorsCristiana Callieri; Manuela Coci; Ester M. Eckert; Michaela M. Salcher; Roberto Bertoni
Text328498 2014 10.4081/jlimnol.2014.937 ISI Web of Science WOS 000338928300005 Scopus 2 s2.0 84893939264 Archaea and Bacteria Thaumarchaeota dark inorganic carbon uptake Lake Maggiore hypolimnion Archaea and Bacteria in deep lake hypolimnion in situ dark inorganic carbon uptake Cristiana Callieri; Manuela Coci; Ester M. Eckert; Michaela M. Salcher; Roberto Bertoni CNR Inst Ecosyst Study; University of Zurich 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 e. g., 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 in situ dark C 14 HCO3 incorporation with a new custom made apparatus, which takes samples and adds tracers in situ. 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 C 14 HCO3 incorporations had lower standard deviation in in situ 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 mu g 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 C 14 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. 73 Published version Articolo 2014_Journal_of_Limnology_73_1_47_54.pdf Articolo in rivista Istituto per lo Studio degli Ecosistemi. 1129 5767 Journal of limnology Testo stamp. Journal of limnology Testo stamp. J. limnol. Testo stamp. Journal of limnology. Testo stamp. roberto.bertoni BERTONI ROBERTO cristiana.callieri CALLIERI CRISTIANA TA.P04.016.004 Ecologia teorica e applicata degli ecosistemi acquatici