Microbial Loop Dynamics in Antarctic Sea-Ice
Sea-ice is a predominant feature of polar oceans and exerts a unique influence on marine ecosystems. The annual circumpolar expansion of sea-ice around Antarctica provides a stable platform for the in situ colonisation and growth of a diverse assemblage of microbes that are integral to the energy ba...
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ftvictoriauwfig:oai:figshare.com:article/16968115 2023-05-15T13:35:14+02:00 Microbial Loop Dynamics in Antarctic Sea-Ice Martin, Andrew Robert 2009-01-01T00:00:00Z https://doi.org/10.26686/wgtn.16968115.v1 https://figshare.com/articles/thesis/Microbial_Loop_Dynamics_in_Antarctic_Sea-Ice/16968115 unknown doi:10.26686/wgtn.16968115.v1 https://figshare.com/articles/thesis/Microbial_Loop_Dynamics_in_Antarctic_Sea-Ice/16968115 Author Retains Copyright Biological Sciences not elsewhere classified Antarctica Marine ecology Microbial ecology School: School of Biological Sciences 069999 Biological Sciences not elsewhere classified Marsden: 270307 Microbial Ecology Degree Discipline: Ecology and Biodiversity Degree Level: Doctoral Degree Name: Doctor of Philosophy Text Thesis 2009 ftvictoriauwfig https://doi.org/10.26686/wgtn.16968115.v1 2021-11-11T00:03:47Z Sea-ice is a predominant feature of polar oceans and exerts a unique influence on marine ecosystems. The annual circumpolar expansion of sea-ice around Antarctica provides a stable platform for the in situ colonisation and growth of a diverse assemblage of microbes that are integral to the energy base of the Southern Ocean. An active microbial loop has been proposed to operate within the ice matrix connecting bacteria, microalgae and protozoa, but validating this metabolic pathway has historically relied on bulk correlations of chlorophyll a (a surrogate for microalgal biomass) and estimates of bacterial production or abundance. I investigate the microbial loop using a range of physiological, genetic, and ecological techniques to determine whether the photosynthate exuded by phototrophic microalgae serves as a growth substrate for heterotrophic bacteria. This link is examined at a range of spatial (in vitro and in situ experiments) and temporal (8 hours to 18 days) scales by manipulating the supply of algal-derived photosynthate and documenting the subsequent change in bacterial metabolic activity, cell abundance and community composition. Single-cell analysis of both bacterial membrane integrity and intracellular activity revealed that sea ice is among the most productive microbial habitats. In short-term in vitro experiments, increased availability of dissolved organic matter (DOM) was shown to elicit a rapid metabolic response in sea ice bacteria, however single-activity was significantly reduced in treatments where photosynthate was restricted by either removing the majority of algal cells or inhibiting photosynthesis with 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU). To verify this metabolic response, microcosm simulations were conducted over a period of 9 days with microbes derived from two regions of the ice (bottom layer and high-salinity surface region) with presumed differences in the concentration of DOM. Metabolic activity was relatively low in bacteria derived from the high-saline region of the ... Thesis Antarc* Antarctic Antarctica Sea ice Southern Ocean Open Access Victoria University of Wellington / Te Herenga Waka Antarctic Southern Ocean Marsden ENVELOPE(66.067,66.067,-67.867,-67.867) |
institution |
Open Polar |
collection |
Open Access Victoria University of Wellington / Te Herenga Waka |
op_collection_id |
ftvictoriauwfig |
language |
unknown |
topic |
Biological Sciences not elsewhere classified Antarctica Marine ecology Microbial ecology School: School of Biological Sciences 069999 Biological Sciences not elsewhere classified Marsden: 270307 Microbial Ecology Degree Discipline: Ecology and Biodiversity Degree Level: Doctoral Degree Name: Doctor of Philosophy |
spellingShingle |
Biological Sciences not elsewhere classified Antarctica Marine ecology Microbial ecology School: School of Biological Sciences 069999 Biological Sciences not elsewhere classified Marsden: 270307 Microbial Ecology Degree Discipline: Ecology and Biodiversity Degree Level: Doctoral Degree Name: Doctor of Philosophy Martin, Andrew Robert Microbial Loop Dynamics in Antarctic Sea-Ice |
topic_facet |
Biological Sciences not elsewhere classified Antarctica Marine ecology Microbial ecology School: School of Biological Sciences 069999 Biological Sciences not elsewhere classified Marsden: 270307 Microbial Ecology Degree Discipline: Ecology and Biodiversity Degree Level: Doctoral Degree Name: Doctor of Philosophy |
description |
Sea-ice is a predominant feature of polar oceans and exerts a unique influence on marine ecosystems. The annual circumpolar expansion of sea-ice around Antarctica provides a stable platform for the in situ colonisation and growth of a diverse assemblage of microbes that are integral to the energy base of the Southern Ocean. An active microbial loop has been proposed to operate within the ice matrix connecting bacteria, microalgae and protozoa, but validating this metabolic pathway has historically relied on bulk correlations of chlorophyll a (a surrogate for microalgal biomass) and estimates of bacterial production or abundance. I investigate the microbial loop using a range of physiological, genetic, and ecological techniques to determine whether the photosynthate exuded by phototrophic microalgae serves as a growth substrate for heterotrophic bacteria. This link is examined at a range of spatial (in vitro and in situ experiments) and temporal (8 hours to 18 days) scales by manipulating the supply of algal-derived photosynthate and documenting the subsequent change in bacterial metabolic activity, cell abundance and community composition. Single-cell analysis of both bacterial membrane integrity and intracellular activity revealed that sea ice is among the most productive microbial habitats. In short-term in vitro experiments, increased availability of dissolved organic matter (DOM) was shown to elicit a rapid metabolic response in sea ice bacteria, however single-activity was significantly reduced in treatments where photosynthate was restricted by either removing the majority of algal cells or inhibiting photosynthesis with 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU). To verify this metabolic response, microcosm simulations were conducted over a period of 9 days with microbes derived from two regions of the ice (bottom layer and high-salinity surface region) with presumed differences in the concentration of DOM. Metabolic activity was relatively low in bacteria derived from the high-saline region of the ... |
format |
Thesis |
author |
Martin, Andrew Robert |
author_facet |
Martin, Andrew Robert |
author_sort |
Martin, Andrew Robert |
title |
Microbial Loop Dynamics in Antarctic Sea-Ice |
title_short |
Microbial Loop Dynamics in Antarctic Sea-Ice |
title_full |
Microbial Loop Dynamics in Antarctic Sea-Ice |
title_fullStr |
Microbial Loop Dynamics in Antarctic Sea-Ice |
title_full_unstemmed |
Microbial Loop Dynamics in Antarctic Sea-Ice |
title_sort |
microbial loop dynamics in antarctic sea-ice |
publishDate |
2009 |
url |
https://doi.org/10.26686/wgtn.16968115.v1 https://figshare.com/articles/thesis/Microbial_Loop_Dynamics_in_Antarctic_Sea-Ice/16968115 |
long_lat |
ENVELOPE(66.067,66.067,-67.867,-67.867) |
geographic |
Antarctic Southern Ocean Marsden |
geographic_facet |
Antarctic Southern Ocean Marsden |
genre |
Antarc* Antarctic Antarctica Sea ice Southern Ocean |
genre_facet |
Antarc* Antarctic Antarctica Sea ice Southern Ocean |
op_relation |
doi:10.26686/wgtn.16968115.v1 https://figshare.com/articles/thesis/Microbial_Loop_Dynamics_in_Antarctic_Sea-Ice/16968115 |
op_rights |
Author Retains Copyright |
op_doi |
https://doi.org/10.26686/wgtn.16968115.v1 |
_version_ |
1766063139411984384 |