Carbon dynamics in highly heterotrophic subarctic thaw ponds.
Global warming has accelerated the formation of permafrost thaw ponds in several subarctic and arctic regions. These ponds are net heterotrophic as evidenced by their greenhouse gas (GHG) supersaturation levels (CO₂ and CH₄), and generally receive large terrestrial carbon inputs from the thawing and...
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ftinrsquebec:oai:espace.inrs.ca:3925 2023-05-15T15:15:44+02:00 Carbon dynamics in highly heterotrophic subarctic thaw ponds. Roiha, Toni Laurion, Isabelle Rautio, Milla 2015 application/pdf https://espace.inrs.ca/id/eprint/3925/ https://espace.inrs.ca/id/eprint/3925/1/P2734.pdf https://doi.org/10.5194/bg-12-7223-2015 en eng https://espace.inrs.ca/id/eprint/3925/1/P2734.pdf Roiha, Toni, Laurion, Isabelle et Rautio, Milla (2015). Carbon dynamics in highly heterotrophic subarctic thaw ponds. Biogeosciences , vol. 12 , nº 23. p. 7223-7237. DOI:10.5194/bg-12-7223-2015 <https://doi.org/10.5194/bg-12-7223-2015>. doi:10.5194/bg-12-7223-2015 carbon bacterioplankton dissolved organic matter environmental gradient permafrost pond primary production subarctic region thawing thermokars Article Évalué par les pairs 2015 ftinrsquebec https://doi.org/10.5194/bg-12-7223-2015 2023-02-10T11:42:46Z Global warming has accelerated the formation of permafrost thaw ponds in several subarctic and arctic regions. These ponds are net heterotrophic as evidenced by their greenhouse gas (GHG) supersaturation levels (CO₂ and CH₄), and generally receive large terrestrial carbon inputs from the thawing and eroding permafrost. We measured seasonal and vertical variations in the concentration and type of dissolved organic matter (DOM) in five subarctic thaw (thermokarst) ponds in northern Quebec, and explored how environmental gradients influenced heterotrophic and phototrophic biomass and productivity. Late winter DOM had low aromaticity indicating reduced inputs of terrestrial carbon, while the high concentration of dissolved organic carbon (DOC) suggests that some production of non-chromophoric dissolved compounds by the microbial food web took place under the ice cover. Summer DOM had a strong terrestrial signature, but was also characterized with significant inputs of algal-derived carbon, especially at the pond surface. During late winter, bacterial production was low (maximum of 0.8 mg C m⁻³ d⁻¹) and was largely based on free-living bacterioplankton (58 %). Bacterial production in summer was high (up to 58 mg C m⁻³ d⁻¹), dominated by particle-attached bacteria (67 %), and strongly correlated to the amount of terrestrial carbon. Primary production was restricted to summer surface waters due to strong light limitation deeper in the water column or in winter. The phototrophic biomass was equal to the heterotrophic biomass, but as the algae were mostly composed of mixotrophic species, most probably they used bacteria rather than solar energy in such shaded ponds. According to the δ13C analyses, non-algal carbon supported 51 % of winter and 37 % of summer biomass of the phantom midge larvae, Chaoborus sp., that are at the top of the trophic chain. Our results point to a strong heterotrophic energy pathway in these thaw pond ecosystems, where bacterioplankton dominates the production of new carbon in both summer and ... Article in Journal/Newspaper Arctic Global warming Ice permafrost Subarctic Thermokarst Institut national de la recherche scientifique, Québec: Espace INRS Arctic Biogeosciences 12 23 7223 7237 |
institution |
Open Polar |
collection |
Institut national de la recherche scientifique, Québec: Espace INRS |
op_collection_id |
ftinrsquebec |
language |
English |
topic |
carbon bacterioplankton dissolved organic matter environmental gradient permafrost pond primary production subarctic region thawing thermokars |
spellingShingle |
carbon bacterioplankton dissolved organic matter environmental gradient permafrost pond primary production subarctic region thawing thermokars Roiha, Toni Laurion, Isabelle Rautio, Milla Carbon dynamics in highly heterotrophic subarctic thaw ponds. |
topic_facet |
carbon bacterioplankton dissolved organic matter environmental gradient permafrost pond primary production subarctic region thawing thermokars |
description |
Global warming has accelerated the formation of permafrost thaw ponds in several subarctic and arctic regions. These ponds are net heterotrophic as evidenced by their greenhouse gas (GHG) supersaturation levels (CO₂ and CH₄), and generally receive large terrestrial carbon inputs from the thawing and eroding permafrost. We measured seasonal and vertical variations in the concentration and type of dissolved organic matter (DOM) in five subarctic thaw (thermokarst) ponds in northern Quebec, and explored how environmental gradients influenced heterotrophic and phototrophic biomass and productivity. Late winter DOM had low aromaticity indicating reduced inputs of terrestrial carbon, while the high concentration of dissolved organic carbon (DOC) suggests that some production of non-chromophoric dissolved compounds by the microbial food web took place under the ice cover. Summer DOM had a strong terrestrial signature, but was also characterized with significant inputs of algal-derived carbon, especially at the pond surface. During late winter, bacterial production was low (maximum of 0.8 mg C m⁻³ d⁻¹) and was largely based on free-living bacterioplankton (58 %). Bacterial production in summer was high (up to 58 mg C m⁻³ d⁻¹), dominated by particle-attached bacteria (67 %), and strongly correlated to the amount of terrestrial carbon. Primary production was restricted to summer surface waters due to strong light limitation deeper in the water column or in winter. The phototrophic biomass was equal to the heterotrophic biomass, but as the algae were mostly composed of mixotrophic species, most probably they used bacteria rather than solar energy in such shaded ponds. According to the δ13C analyses, non-algal carbon supported 51 % of winter and 37 % of summer biomass of the phantom midge larvae, Chaoborus sp., that are at the top of the trophic chain. Our results point to a strong heterotrophic energy pathway in these thaw pond ecosystems, where bacterioplankton dominates the production of new carbon in both summer and ... |
format |
Article in Journal/Newspaper |
author |
Roiha, Toni Laurion, Isabelle Rautio, Milla |
author_facet |
Roiha, Toni Laurion, Isabelle Rautio, Milla |
author_sort |
Roiha, Toni |
title |
Carbon dynamics in highly heterotrophic subarctic thaw ponds. |
title_short |
Carbon dynamics in highly heterotrophic subarctic thaw ponds. |
title_full |
Carbon dynamics in highly heterotrophic subarctic thaw ponds. |
title_fullStr |
Carbon dynamics in highly heterotrophic subarctic thaw ponds. |
title_full_unstemmed |
Carbon dynamics in highly heterotrophic subarctic thaw ponds. |
title_sort |
carbon dynamics in highly heterotrophic subarctic thaw ponds. |
publishDate |
2015 |
url |
https://espace.inrs.ca/id/eprint/3925/ https://espace.inrs.ca/id/eprint/3925/1/P2734.pdf https://doi.org/10.5194/bg-12-7223-2015 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic Global warming Ice permafrost Subarctic Thermokarst |
genre_facet |
Arctic Global warming Ice permafrost Subarctic Thermokarst |
op_relation |
https://espace.inrs.ca/id/eprint/3925/1/P2734.pdf Roiha, Toni, Laurion, Isabelle et Rautio, Milla (2015). Carbon dynamics in highly heterotrophic subarctic thaw ponds. Biogeosciences , vol. 12 , nº 23. p. 7223-7237. DOI:10.5194/bg-12-7223-2015 <https://doi.org/10.5194/bg-12-7223-2015>. doi:10.5194/bg-12-7223-2015 |
op_doi |
https://doi.org/10.5194/bg-12-7223-2015 |
container_title |
Biogeosciences |
container_volume |
12 |
container_issue |
23 |
container_start_page |
7223 |
op_container_end_page |
7237 |
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1766346071481516032 |