Remote Sensing Phenology of Antarctic Green and Red Snow Algae Using WorldView Satellites
Snow algae are an important group of terrestrial photosynthetic organisms in Antarctica, where they mostly grow in low lying coastal snow fields. Reliable observations of Antarctic snow algae are difficult owing to the transient nature of their blooms and the logistics involved to travel and work th...
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ftunivcam:oai:www.repository.cam.ac.uk:1810/324792 2023-07-30T03:56:08+02:00 Remote Sensing Phenology of Antarctic Green and Red Snow Algae Using WorldView Satellites Gray, Andrew Krolikowski, Monika Fretwell, Peter Convey, Peter Peck, Lloyd S. Mendelova, Monika Smith, Alison G. Davey, Matthew P. 2021-07-05T17:35:42Z text/xml application/zip application/pdf https://doi.org/10.17863/CAM.72245 https://www.repository.cam.ac.uk/handle/1810/324792 en eng Frontiers Media S.A. Frontiers in Plant Science doi:10.17863/CAM.72245 https://www.repository.cam.ac.uk/handle/1810/324792 Plant Science snow algae Antarctica remote sensing snow satellites WorldView ecology Article 2021 ftunivcam https://doi.org/10.17863/CAM.72245 2023-07-10T22:01:46Z Snow algae are an important group of terrestrial photosynthetic organisms in Antarctica, where they mostly grow in low lying coastal snow fields. Reliable observations of Antarctic snow algae are difficult owing to the transient nature of their blooms and the logistics involved to travel and work there. Previous studies have used Sentinel 2 satellite imagery to detect and monitor snow algal blooms remotely, but were limited by the coarse spatial resolution and difficulties detecting red blooms. Here, for the first time, we use high-resolution WorldView multispectral satellite imagery to study Antarctic snow algal blooms in detail, tracking the growth of red and green blooms throughout the summer. Our remote sensing approach was developed alongside two Antarctic field seasons, where field spectroscopy was used to build a detection model capable of estimating cell density. Global Positioning System (GPS) tagging of blooms and in situ life cycle analysis was used to validate and verify our model output. WorldView imagery was then used successfully to identify red and green snow algae on Anchorage Island (Ryder Bay, 67°S), estimating peak coverage to be 9.48 × 104 and 6.26 × 104 m2, respectively. Combined, this was greater than terrestrial vegetation area coverage for the island, measured using a normalized difference vegetation index. Green snow algae had greater cell density and average layer thickness than red blooms (6.0 × 104 vs. 4.3 × 104 cells ml−1) and so for Anchorage Island we estimated that green algae dry biomass was over three times that of red algae (567 vs. 180 kg, respectively). Because the high spatial resolution of the WorldView imagery and its ability to detect red blooms, calculated snow algal area was 17.5 times greater than estimated with Sentinel 2 imagery. This highlights a scaling problem of using coarse resolution imagery and suggests snow algal contribution to net primary productivity on Antarctica may be far greater than previously recognized. Article in Journal/Newspaper Anchorage Island Antarc* Antarctic Antarctica Apollo - University of Cambridge Repository Anchorage Anchorage Island ENVELOPE(-68.214,-68.214,-67.605,-67.605) Antarctic Ryder ENVELOPE(-68.333,-68.333,-67.566,-67.566) Ryder Bay ENVELOPE(-68.333,-68.333,-67.567,-67.567) |
institution |
Open Polar |
collection |
Apollo - University of Cambridge Repository |
op_collection_id |
ftunivcam |
language |
English |
topic |
Plant Science snow algae Antarctica remote sensing snow satellites WorldView ecology |
spellingShingle |
Plant Science snow algae Antarctica remote sensing snow satellites WorldView ecology Gray, Andrew Krolikowski, Monika Fretwell, Peter Convey, Peter Peck, Lloyd S. Mendelova, Monika Smith, Alison G. Davey, Matthew P. Remote Sensing Phenology of Antarctic Green and Red Snow Algae Using WorldView Satellites |
topic_facet |
Plant Science snow algae Antarctica remote sensing snow satellites WorldView ecology |
description |
Snow algae are an important group of terrestrial photosynthetic organisms in Antarctica, where they mostly grow in low lying coastal snow fields. Reliable observations of Antarctic snow algae are difficult owing to the transient nature of their blooms and the logistics involved to travel and work there. Previous studies have used Sentinel 2 satellite imagery to detect and monitor snow algal blooms remotely, but were limited by the coarse spatial resolution and difficulties detecting red blooms. Here, for the first time, we use high-resolution WorldView multispectral satellite imagery to study Antarctic snow algal blooms in detail, tracking the growth of red and green blooms throughout the summer. Our remote sensing approach was developed alongside two Antarctic field seasons, where field spectroscopy was used to build a detection model capable of estimating cell density. Global Positioning System (GPS) tagging of blooms and in situ life cycle analysis was used to validate and verify our model output. WorldView imagery was then used successfully to identify red and green snow algae on Anchorage Island (Ryder Bay, 67°S), estimating peak coverage to be 9.48 × 104 and 6.26 × 104 m2, respectively. Combined, this was greater than terrestrial vegetation area coverage for the island, measured using a normalized difference vegetation index. Green snow algae had greater cell density and average layer thickness than red blooms (6.0 × 104 vs. 4.3 × 104 cells ml−1) and so for Anchorage Island we estimated that green algae dry biomass was over three times that of red algae (567 vs. 180 kg, respectively). Because the high spatial resolution of the WorldView imagery and its ability to detect red blooms, calculated snow algal area was 17.5 times greater than estimated with Sentinel 2 imagery. This highlights a scaling problem of using coarse resolution imagery and suggests snow algal contribution to net primary productivity on Antarctica may be far greater than previously recognized. |
format |
Article in Journal/Newspaper |
author |
Gray, Andrew Krolikowski, Monika Fretwell, Peter Convey, Peter Peck, Lloyd S. Mendelova, Monika Smith, Alison G. Davey, Matthew P. |
author_facet |
Gray, Andrew Krolikowski, Monika Fretwell, Peter Convey, Peter Peck, Lloyd S. Mendelova, Monika Smith, Alison G. Davey, Matthew P. |
author_sort |
Gray, Andrew |
title |
Remote Sensing Phenology of Antarctic Green and Red Snow Algae Using WorldView Satellites |
title_short |
Remote Sensing Phenology of Antarctic Green and Red Snow Algae Using WorldView Satellites |
title_full |
Remote Sensing Phenology of Antarctic Green and Red Snow Algae Using WorldView Satellites |
title_fullStr |
Remote Sensing Phenology of Antarctic Green and Red Snow Algae Using WorldView Satellites |
title_full_unstemmed |
Remote Sensing Phenology of Antarctic Green and Red Snow Algae Using WorldView Satellites |
title_sort |
remote sensing phenology of antarctic green and red snow algae using worldview satellites |
publisher |
Frontiers Media S.A. |
publishDate |
2021 |
url |
https://doi.org/10.17863/CAM.72245 https://www.repository.cam.ac.uk/handle/1810/324792 |
long_lat |
ENVELOPE(-68.214,-68.214,-67.605,-67.605) ENVELOPE(-68.333,-68.333,-67.566,-67.566) ENVELOPE(-68.333,-68.333,-67.567,-67.567) |
geographic |
Anchorage Anchorage Island Antarctic Ryder Ryder Bay |
geographic_facet |
Anchorage Anchorage Island Antarctic Ryder Ryder Bay |
genre |
Anchorage Island Antarc* Antarctic Antarctica |
genre_facet |
Anchorage Island Antarc* Antarctic Antarctica |
op_relation |
doi:10.17863/CAM.72245 https://www.repository.cam.ac.uk/handle/1810/324792 |
op_doi |
https://doi.org/10.17863/CAM.72245 |
_version_ |
1772810996651393024 |