Climate change impact on ecosystems of Prince Edward Islands: role of oceanic mesoscale processes
The subantarctic Prince Edward Islands (PEIs, 47◦S-38◦E) are classified as isolated and hostile regions, in which the terrestrial and marine ecosystems are relatively simple and extremely sensitive to perturbations. The island’s location, between the Subantarctic Front (SAF) and the Polar Front (PF)...
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ftunivcapetownir:oai:localhost:11427/30330 2023-05-15T13:54:58+02:00 Climate change impact on ecosystems of Prince Edward Islands: role of oceanic mesoscale processes Asdar, Sarah Ansorge, Isabel Penven, Pierrick Deshayes, Julie 2019 application/pdf http://hdl.handle.net/11427/30330 https://open.uct.ac.za/bitstream/11427/30330/1/thesis_sci_2019_asdar_sarah.pdf eng eng Faculty of Science Department of Oceanography http://hdl.handle.net/11427/30330 https://open.uct.ac.za/bitstream/11427/30330/1/thesis_sci_2019_asdar_sarah.pdf Climate Change Impact Doctoral Thesis Doctoral PhD 2019 ftunivcapetownir 2022-09-13T05:48:24Z The subantarctic Prince Edward Islands (PEIs, 47◦S-38◦E) are classified as isolated and hostile regions, in which the terrestrial and marine ecosystems are relatively simple and extremely sensitive to perturbations. The island’s location, between the Subantarctic Front (SAF) and the Polar Front (PF), bordering the Antarctic Circumpolar Current (ACC) provides an ideal natural laboratory for studying how organisms, ecological processes and ecosystems respond to a changing climate in the Southern Ocean. Recent studies have proposed that climate changes reported at the islands may correspond in time to a southward shift of the ACC and in particular of the SAF. This southward migration in the geographic position of major ocean fronts is likely to coincide with dramatic changes in the distribution of species and total productivity of this region. However, there are other sources of variability in the hydrodynamic conditions around the PEIs: upstream of the islands, at the South West Indian Ridge (SWIR), a region of high eddy kinetic activity produces mesoscale features that directly irrigate the PEIs and may impact their marine environment. Based on satellite altimetry in that region, the positions of the SAF and PF were found to be highly variable at interannual and monthly time scales. They also revealed a significant long-term southward trend which was highlighted at the Southern Ocean scale. The mesoscale activity also showed an interannual and intra-annual variability and a decrease in eddy kinetic energy over 24 years was observed in the region. At a more local scale, we highlighted that the archipelago’s environment was impacted by the mesoscale features produced at the SWIR. The temperature, the mixed layer and velocities recorded between the islands were clearly affected by the eddies passing in the vicinity of the PEIs. Moreover, a large signal dominating the main current time series appeared to be a tidal signal, another important driver of variability of the circulation in between the two islands. On a ... Doctoral or Postdoctoral Thesis Antarc* Antarctic Prince Edward Islands Southern Ocean University of Cape Town: OpenUCT Antarctic Indian Southern Ocean The Antarctic |
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University of Cape Town: OpenUCT |
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English |
topic |
Climate Change Impact |
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Climate Change Impact Asdar, Sarah Climate change impact on ecosystems of Prince Edward Islands: role of oceanic mesoscale processes |
topic_facet |
Climate Change Impact |
description |
The subantarctic Prince Edward Islands (PEIs, 47◦S-38◦E) are classified as isolated and hostile regions, in which the terrestrial and marine ecosystems are relatively simple and extremely sensitive to perturbations. The island’s location, between the Subantarctic Front (SAF) and the Polar Front (PF), bordering the Antarctic Circumpolar Current (ACC) provides an ideal natural laboratory for studying how organisms, ecological processes and ecosystems respond to a changing climate in the Southern Ocean. Recent studies have proposed that climate changes reported at the islands may correspond in time to a southward shift of the ACC and in particular of the SAF. This southward migration in the geographic position of major ocean fronts is likely to coincide with dramatic changes in the distribution of species and total productivity of this region. However, there are other sources of variability in the hydrodynamic conditions around the PEIs: upstream of the islands, at the South West Indian Ridge (SWIR), a region of high eddy kinetic activity produces mesoscale features that directly irrigate the PEIs and may impact their marine environment. Based on satellite altimetry in that region, the positions of the SAF and PF were found to be highly variable at interannual and monthly time scales. They also revealed a significant long-term southward trend which was highlighted at the Southern Ocean scale. The mesoscale activity also showed an interannual and intra-annual variability and a decrease in eddy kinetic energy over 24 years was observed in the region. At a more local scale, we highlighted that the archipelago’s environment was impacted by the mesoscale features produced at the SWIR. The temperature, the mixed layer and velocities recorded between the islands were clearly affected by the eddies passing in the vicinity of the PEIs. Moreover, a large signal dominating the main current time series appeared to be a tidal signal, another important driver of variability of the circulation in between the two islands. On a ... |
author2 |
Ansorge, Isabel Penven, Pierrick Deshayes, Julie |
format |
Doctoral or Postdoctoral Thesis |
author |
Asdar, Sarah |
author_facet |
Asdar, Sarah |
author_sort |
Asdar, Sarah |
title |
Climate change impact on ecosystems of Prince Edward Islands: role of oceanic mesoscale processes |
title_short |
Climate change impact on ecosystems of Prince Edward Islands: role of oceanic mesoscale processes |
title_full |
Climate change impact on ecosystems of Prince Edward Islands: role of oceanic mesoscale processes |
title_fullStr |
Climate change impact on ecosystems of Prince Edward Islands: role of oceanic mesoscale processes |
title_full_unstemmed |
Climate change impact on ecosystems of Prince Edward Islands: role of oceanic mesoscale processes |
title_sort |
climate change impact on ecosystems of prince edward islands: role of oceanic mesoscale processes |
publisher |
Faculty of Science |
publishDate |
2019 |
url |
http://hdl.handle.net/11427/30330 https://open.uct.ac.za/bitstream/11427/30330/1/thesis_sci_2019_asdar_sarah.pdf |
geographic |
Antarctic Indian Southern Ocean The Antarctic |
geographic_facet |
Antarctic Indian Southern Ocean The Antarctic |
genre |
Antarc* Antarctic Prince Edward Islands Southern Ocean |
genre_facet |
Antarc* Antarctic Prince Edward Islands Southern Ocean |
op_relation |
http://hdl.handle.net/11427/30330 https://open.uct.ac.za/bitstream/11427/30330/1/thesis_sci_2019_asdar_sarah.pdf |
_version_ |
1766261170230001664 |