Microbial dynamics in high latitude ecosystems. Responses to mixing, runoff and seasonal variation a rapidly changing environment
The pronounced warming at high latitude alters a range of physical conditions i.e. the magnitude of runoff, sea-ice extent and strength of stratification and thus affect the biological systems. As microorganisms form the living base of the pelagic food web and are the major drives of biogeochemical...
Published in: | Aquatic Microbial Ecology |
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Main Author: | |
Format: | Doctoral or Postdoctoral Thesis |
Language: | English |
Published: |
The University of Bergen
2017
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Subjects: | |
Online Access: | https://hdl.handle.net/1956/17362 |
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ftunivbergen:oai:bora.uib.no:1956/17362 |
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openpolar |
institution |
Open Polar |
collection |
University of Bergen: Bergen Open Research Archive (BORA-UiB) |
op_collection_id |
ftunivbergen |
language |
English |
description |
The pronounced warming at high latitude alters a range of physical conditions i.e. the magnitude of runoff, sea-ice extent and strength of stratification and thus affect the biological systems. As microorganisms form the living base of the pelagic food web and are the major drives of biogeochemical processing it is critical to understand their response to these changes. This Ph.D. project focuses on the smallest (<2μm) and most abundant microorganisms, heterotrophic bacterioplankton (bacteria and Archaea) and autotrophic picophytoplankton, and the factors regulating their abundance, diversity and activity in the Arctic-Subarctic Atlantic Ocean. The study covers hydrographic regimes off and around Iceland, Norway (including Svalbard) and East Greenland (60-83°N), and combines field observations and experiments during different seasons. The main aim is to elucidate the three following topics: 1) Challenges phytoplankton face related to high seasonality and low light conditions 2) Bioavailability of dissolved organic matter (DOM) to bacterial communities and their response to an increase in terrestrial loading 3) Importance of top-down control by heterotrophic nanoflagellates (HNF) on both pico-sized phytoplankton and bacteria. My study underpins that picophytoplankton are important contributors to primary production, especially during the winter-spring transition (Paper I and III) and autumn (Paper V). They boosted the growth of heterotrophic microorganisms before the onset of the diatom spring bloom in the Subarctic Atlantic (Paper I) and dominated the phytoplankton biomass in the high turbid parts of a NE Greenland fjord influenced by glacial meltwater (Paper V). Picophytoplankton were better adapted to low light conditions and demonstrated higher growth rates, than larger phytoplankton (Paper I, II, III, V). In the Polar-influenced water near Greenland, Synechococcus were negligible, while in the Atlantic influenced waters picoeukaryotes and Synechococcus were often equally abundant and the latter dominated ... |
format |
Doctoral or Postdoctoral Thesis |
author |
Paulsen, Maria Lund |
spellingShingle |
Paulsen, Maria Lund Microbial dynamics in high latitude ecosystems. Responses to mixing, runoff and seasonal variation a rapidly changing environment |
author_facet |
Paulsen, Maria Lund |
author_sort |
Paulsen, Maria Lund |
title |
Microbial dynamics in high latitude ecosystems. Responses to mixing, runoff and seasonal variation a rapidly changing environment |
title_short |
Microbial dynamics in high latitude ecosystems. Responses to mixing, runoff and seasonal variation a rapidly changing environment |
title_full |
Microbial dynamics in high latitude ecosystems. Responses to mixing, runoff and seasonal variation a rapidly changing environment |
title_fullStr |
Microbial dynamics in high latitude ecosystems. Responses to mixing, runoff and seasonal variation a rapidly changing environment |
title_full_unstemmed |
Microbial dynamics in high latitude ecosystems. Responses to mixing, runoff and seasonal variation a rapidly changing environment |
title_sort |
microbial dynamics in high latitude ecosystems. responses to mixing, runoff and seasonal variation a rapidly changing environment |
publisher |
The University of Bergen |
publishDate |
2017 |
url |
https://hdl.handle.net/1956/17362 |
geographic |
Arctic Greenland Norway Svalbard |
geographic_facet |
Arctic Greenland Norway Svalbard |
genre |
Arctic Arctic East Greenland Greenland Iceland Phytoplankton Sea ice Subarctic Svalbard |
genre_facet |
Arctic Arctic East Greenland Greenland Iceland Phytoplankton Sea ice Subarctic Svalbard |
op_relation |
Paper I: Paulsen ML, Riisgaard K, Thingstad TF, John MS and Nielsen TG. (2015). Winter−spring transition in the subarctic Atlantic: microbial response to deep mixing and pre-bloom production. Aquat. Microb. Ecol. 76, 49–69. The article is available at: http://hdl.handle.net/1956/10971 Paper II: Paulsen ML, Riisgaard K, John MS, Thingstad TF and Nielsen TG. (2017). Heterotrophic nanoflagellate grazing facilitates subarctic Atlantic spring bloom development. Aquat. Microb. Ecol. 78, 161–176. The article will be available in BORA after the publisher's embargo: http://hdl.handle.net/1956/17357 . The published version is available at: https://doi.org/10.3354/ame01807 Paper III: Paulsen ML, Doré H, Garczarek L, Seuthe L, Müller O, Sandaa R-A, Bratbak G and Larsen A. (2016). Synechococcus in the Atlantic Gateway to the Arctic Ocean. Front. Mar. Sci. 3, 191. The article is available at: http://hdl.handle.net/1956/15716 Paper IV: Paulsen ML, Nielsen SEB, Müller O, Møller EF, Stedmon CA, Juul-Pedersen T, Markager S, Sejr MK, Huertas AD, Larsen A and Middelboe M. (2017). Carbon bioavailability in a high Arctic fjord influenced by glacial meltwater, NE Greenland. Front. Mar. Sci. 4, 176. The article is available at: http://hdl.handle.net/1956/17359 Paper V: Paulsen ML, Müller O, Larsen A, Møller EF, Sejr MK, Middelboe, M and Stedmon CA (2018). Biological transformation of Arctic dissolved organic matter in a NE Greenland fjord. Limnol. Oceanogr., in press. The article is available at: http://hdl.handle.net/1956/18992 https://hdl.handle.net/1956/17362 cristin:1511524 |
op_rights |
Copyright the author. All rights reserved |
op_doi |
https://doi.org/10.3354/ame01807 |
container_title |
Aquatic Microbial Ecology |
container_volume |
78 |
container_issue |
3 |
container_start_page |
161 |
op_container_end_page |
176 |
_version_ |
1766301083296071680 |
spelling |
ftunivbergen:oai:bora.uib.no:1956/17362 2023-05-15T14:27:22+02:00 Microbial dynamics in high latitude ecosystems. Responses to mixing, runoff and seasonal variation a rapidly changing environment Paulsen, Maria Lund 2017-11-08 application/pdf https://hdl.handle.net/1956/17362 eng eng The University of Bergen Paper I: Paulsen ML, Riisgaard K, Thingstad TF, John MS and Nielsen TG. (2015). Winter−spring transition in the subarctic Atlantic: microbial response to deep mixing and pre-bloom production. Aquat. Microb. Ecol. 76, 49–69. The article is available at: http://hdl.handle.net/1956/10971 Paper II: Paulsen ML, Riisgaard K, John MS, Thingstad TF and Nielsen TG. (2017). Heterotrophic nanoflagellate grazing facilitates subarctic Atlantic spring bloom development. Aquat. Microb. Ecol. 78, 161–176. The article will be available in BORA after the publisher's embargo: http://hdl.handle.net/1956/17357 . The published version is available at: https://doi.org/10.3354/ame01807 Paper III: Paulsen ML, Doré H, Garczarek L, Seuthe L, Müller O, Sandaa R-A, Bratbak G and Larsen A. (2016). Synechococcus in the Atlantic Gateway to the Arctic Ocean. Front. Mar. Sci. 3, 191. The article is available at: http://hdl.handle.net/1956/15716 Paper IV: Paulsen ML, Nielsen SEB, Müller O, Møller EF, Stedmon CA, Juul-Pedersen T, Markager S, Sejr MK, Huertas AD, Larsen A and Middelboe M. (2017). Carbon bioavailability in a high Arctic fjord influenced by glacial meltwater, NE Greenland. Front. Mar. Sci. 4, 176. The article is available at: http://hdl.handle.net/1956/17359 Paper V: Paulsen ML, Müller O, Larsen A, Møller EF, Sejr MK, Middelboe, M and Stedmon CA (2018). Biological transformation of Arctic dissolved organic matter in a NE Greenland fjord. Limnol. Oceanogr., in press. The article is available at: http://hdl.handle.net/1956/18992 https://hdl.handle.net/1956/17362 cristin:1511524 Copyright the author. All rights reserved Doctoral thesis 2017 ftunivbergen https://doi.org/10.3354/ame01807 2023-03-14T17:45:04Z The pronounced warming at high latitude alters a range of physical conditions i.e. the magnitude of runoff, sea-ice extent and strength of stratification and thus affect the biological systems. As microorganisms form the living base of the pelagic food web and are the major drives of biogeochemical processing it is critical to understand their response to these changes. This Ph.D. project focuses on the smallest (<2μm) and most abundant microorganisms, heterotrophic bacterioplankton (bacteria and Archaea) and autotrophic picophytoplankton, and the factors regulating their abundance, diversity and activity in the Arctic-Subarctic Atlantic Ocean. The study covers hydrographic regimes off and around Iceland, Norway (including Svalbard) and East Greenland (60-83°N), and combines field observations and experiments during different seasons. The main aim is to elucidate the three following topics: 1) Challenges phytoplankton face related to high seasonality and low light conditions 2) Bioavailability of dissolved organic matter (DOM) to bacterial communities and their response to an increase in terrestrial loading 3) Importance of top-down control by heterotrophic nanoflagellates (HNF) on both pico-sized phytoplankton and bacteria. My study underpins that picophytoplankton are important contributors to primary production, especially during the winter-spring transition (Paper I and III) and autumn (Paper V). They boosted the growth of heterotrophic microorganisms before the onset of the diatom spring bloom in the Subarctic Atlantic (Paper I) and dominated the phytoplankton biomass in the high turbid parts of a NE Greenland fjord influenced by glacial meltwater (Paper V). Picophytoplankton were better adapted to low light conditions and demonstrated higher growth rates, than larger phytoplankton (Paper I, II, III, V). In the Polar-influenced water near Greenland, Synechococcus were negligible, while in the Atlantic influenced waters picoeukaryotes and Synechococcus were often equally abundant and the latter dominated ... Doctoral or Postdoctoral Thesis Arctic Arctic East Greenland Greenland Iceland Phytoplankton Sea ice Subarctic Svalbard University of Bergen: Bergen Open Research Archive (BORA-UiB) Arctic Greenland Norway Svalbard Aquatic Microbial Ecology 78 3 161 176 |