Physical and chemical controls on the abundance and composition of stream microbial mats from the McMurdo Dry Valleys, Antarctica
The McMurdo Dry Valleys of Antarctica are a cold, dry desert, yet perennial microbial mats are abundant in the ephemeral glacial meltwater streams that flow during austral summers. Three types of mats are present (orange, black, and green), and are primarily comprised of filamentous cyanobacteria, N...
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ftunicolboulder:oai:scholar.colorado.edu:envs_gradetds-1025 2023-05-15T13:36:09+02:00 Physical and chemical controls on the abundance and composition of stream microbial mats from the McMurdo Dry Valleys, Antarctica Kohler, Tyler Joe 2015-01-01T08:00:00Z application/pdf https://scholar.colorado.edu/envs_gradetds/25 https://scholar.colorado.edu/cgi/viewcontent.cgi?article=1025&context=envs_gradetds unknown CU Scholar https://scholar.colorado.edu/envs_gradetds/25 https://scholar.colorado.edu/cgi/viewcontent.cgi?article=1025&context=envs_gradetds Environmental Studies Graduate Theses & Dissertations algae climate change simulated scouring Luticola Biogeochemistry Environmental Sciences Fresh Water Studies text 2015 ftunicolboulder 2018-10-07T08:55:49Z The McMurdo Dry Valleys of Antarctica are a cold, dry desert, yet perennial microbial mats are abundant in the ephemeral glacial meltwater streams that flow during austral summers. Three types of mats are present (orange, black, and green), and are primarily comprised of filamentous cyanobacteria, Nostoc, and chlorophytes, respectively. Mat types furthermore occupy distinct habitats within streams, utilizing the benthos, hyporheic zone, and water column, which expose them to different environmental conditions. Due to a lack of lateral inflows, allochthonous organic inputs, and negligible grazing activity, these streams are ideal for the controlled ecological study of microbial mats. Here, I investigated how mats will respond to physical disturbance, alterations in the hydrologic regime, and nutrient liberation from permafrost melt in the future. Specifically, I: 1) quantified and characterized the regrowth of mat biomass, community structure, and elemental stoichiometry after a scouring disturbance, 2) investigated how geomorphology and taxonomic identity influences the response of mat biomass to hydrologic regime in transects monitored over two decades, and 3) evaluated relationships between water chemistry and the elemental and isotopic composition of mat types over longitudinal and valley-wide gradients in Taylor Valley. I found that mats recovered ~20-50% of their biomass over the course of an austral summer following scour. Algal communities were significantly different in composition between disturbed and control treatments, but all samples naturally varied in species and elemental stoichiometry over the study period. When the long-term record of mat biomass was compared with hydrologic variables, stream channel mats (orange and green) had the greatest correlations, while marginal mats (black) showed weaker relationships with flow regime. Relationships also differed as a function of stream geomorphology, indicating the importance of substrata and gradient in conjunction with discharge. Lastly, mats showed unique elemental and isotopic compositions. Green and orange mats within the stream channel most reflected water column nutrient concentrations, while black mats showed significant nitrogen fixation. These results highlight the importance of taxonomic identity and habitat to modeling primary production here and elsewhere, and provide insight to how stream microbial mat communities are formed, maintained, and ultimately persist in an isolated polar desert. Text Antarc* Antarctica McMurdo Dry Valleys permafrost polar desert University of Colorado, Boulder: CU Scholar Austral McMurdo Dry Valleys Taylor Valley ENVELOPE(163.000,163.000,-77.617,-77.617) |
institution |
Open Polar |
collection |
University of Colorado, Boulder: CU Scholar |
op_collection_id |
ftunicolboulder |
language |
unknown |
topic |
algae climate change simulated scouring Luticola Biogeochemistry Environmental Sciences Fresh Water Studies |
spellingShingle |
algae climate change simulated scouring Luticola Biogeochemistry Environmental Sciences Fresh Water Studies Kohler, Tyler Joe Physical and chemical controls on the abundance and composition of stream microbial mats from the McMurdo Dry Valleys, Antarctica |
topic_facet |
algae climate change simulated scouring Luticola Biogeochemistry Environmental Sciences Fresh Water Studies |
description |
The McMurdo Dry Valleys of Antarctica are a cold, dry desert, yet perennial microbial mats are abundant in the ephemeral glacial meltwater streams that flow during austral summers. Three types of mats are present (orange, black, and green), and are primarily comprised of filamentous cyanobacteria, Nostoc, and chlorophytes, respectively. Mat types furthermore occupy distinct habitats within streams, utilizing the benthos, hyporheic zone, and water column, which expose them to different environmental conditions. Due to a lack of lateral inflows, allochthonous organic inputs, and negligible grazing activity, these streams are ideal for the controlled ecological study of microbial mats. Here, I investigated how mats will respond to physical disturbance, alterations in the hydrologic regime, and nutrient liberation from permafrost melt in the future. Specifically, I: 1) quantified and characterized the regrowth of mat biomass, community structure, and elemental stoichiometry after a scouring disturbance, 2) investigated how geomorphology and taxonomic identity influences the response of mat biomass to hydrologic regime in transects monitored over two decades, and 3) evaluated relationships between water chemistry and the elemental and isotopic composition of mat types over longitudinal and valley-wide gradients in Taylor Valley. I found that mats recovered ~20-50% of their biomass over the course of an austral summer following scour. Algal communities were significantly different in composition between disturbed and control treatments, but all samples naturally varied in species and elemental stoichiometry over the study period. When the long-term record of mat biomass was compared with hydrologic variables, stream channel mats (orange and green) had the greatest correlations, while marginal mats (black) showed weaker relationships with flow regime. Relationships also differed as a function of stream geomorphology, indicating the importance of substrata and gradient in conjunction with discharge. Lastly, mats showed unique elemental and isotopic compositions. Green and orange mats within the stream channel most reflected water column nutrient concentrations, while black mats showed significant nitrogen fixation. These results highlight the importance of taxonomic identity and habitat to modeling primary production here and elsewhere, and provide insight to how stream microbial mat communities are formed, maintained, and ultimately persist in an isolated polar desert. |
format |
Text |
author |
Kohler, Tyler Joe |
author_facet |
Kohler, Tyler Joe |
author_sort |
Kohler, Tyler Joe |
title |
Physical and chemical controls on the abundance and composition of stream microbial mats from the McMurdo Dry Valleys, Antarctica |
title_short |
Physical and chemical controls on the abundance and composition of stream microbial mats from the McMurdo Dry Valleys, Antarctica |
title_full |
Physical and chemical controls on the abundance and composition of stream microbial mats from the McMurdo Dry Valleys, Antarctica |
title_fullStr |
Physical and chemical controls on the abundance and composition of stream microbial mats from the McMurdo Dry Valleys, Antarctica |
title_full_unstemmed |
Physical and chemical controls on the abundance and composition of stream microbial mats from the McMurdo Dry Valleys, Antarctica |
title_sort |
physical and chemical controls on the abundance and composition of stream microbial mats from the mcmurdo dry valleys, antarctica |
publisher |
CU Scholar |
publishDate |
2015 |
url |
https://scholar.colorado.edu/envs_gradetds/25 https://scholar.colorado.edu/cgi/viewcontent.cgi?article=1025&context=envs_gradetds |
long_lat |
ENVELOPE(163.000,163.000,-77.617,-77.617) |
geographic |
Austral McMurdo Dry Valleys Taylor Valley |
geographic_facet |
Austral McMurdo Dry Valleys Taylor Valley |
genre |
Antarc* Antarctica McMurdo Dry Valleys permafrost polar desert |
genre_facet |
Antarc* Antarctica McMurdo Dry Valleys permafrost polar desert |
op_source |
Environmental Studies Graduate Theses & Dissertations |
op_relation |
https://scholar.colorado.edu/envs_gradetds/25 https://scholar.colorado.edu/cgi/viewcontent.cgi?article=1025&context=envs_gradetds |
_version_ |
1766074927919661056 |