Physical properties and processes in the Perth Canyon, Western Australia: Links to water column production and seasonal pygmy blue whale abundance
The oceanography of the Perth Canyon, off southwestern Australia, was examined through two major field excursions in austral spring/summer 2003/2004 combined with previous results from field analysis and numerical simulations. Water properties were used to identify water masses and vertical displace...
Published in: | Journal of Marine Systems |
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Online Access: | https://hdl.handle.net/20.500.11937/40847 https://doi.org/10.1016/j.jmarsys.2008.11.008 |
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ftcurtin:oai:espace.curtin.edu.au:20.500.11937/40847 2023-06-11T04:10:42+02:00 Physical properties and processes in the Perth Canyon, Western Australia: Links to water column production and seasonal pygmy blue whale abundance Rennie, Susan Hanson, C. McCauley, Robert Pattiaratchi, C. Burton, C. Bannister, J. Jenner, C. Jenner, M. 2009 restricted https://hdl.handle.net/20.500.11937/40847 https://doi.org/10.1016/j.jmarsys.2008.11.008 unknown Elsevier http://hdl.handle.net/20.500.11937/40847 doi:10.1016/j.jmarsys.2008.11.008 Leeuwin Current - Pygmy blue whales - Submarine canyon - Upwelling - Primary production - Physical oceanography - Perth Canyon - Western Australia Journal Article 2009 ftcurtin https://doi.org/20.500.11937/4084710.1016/j.jmarsys.2008.11.008 2023-05-30T19:41:40Z The oceanography of the Perth Canyon, off southwestern Australia, was examined through two major field excursions in austral spring/summer 2003/2004 combined with previous results from field analysis and numerical simulations. Water properties were used to identify water masses and vertical displacement. The field cruises and numerical simulation indicated unique circulation features of the Leeuwin Current and Undercurrent within the canyon associated with the topographic features. The input of nutrients to the euphotic zone occurred sporadically as the Leeuwin Current generally suppressed upwelling, although the Perth Canyon had increased nutrient concentrations within its rims. The distribution of chlorophyll in the surface layers indicated high spatial variability, with a prevalent deep chlorophyll (and phytoplankton biomass) maximum at ~80 m. Depth-integrated primary production within the study region ranged from 360 to 760 mg C m-2 d-1, which was on average 2.5 times higher than rates measured in continental shelf and off shorewaters north of the canyon.Aggregations of krill and other acoustic backscatter targets were concentrated near the head of the canyon at a range of depths, which may have been promoted by the circulation. The findings here are consistent with seasonal variations in wind and insolation, along with variations in the Leeuwin Current, influencing the seasonal changes and mesoscale features within the region, while the canyon promotes localised upwelling, and enhances both pelagic production and physical aggregation of plankton to attract the whales. Canyon processes must be combined with outside factors to allow upwelled nutrients to reach the photic zone. It is concluded that a combination of factors, rather than one factor alone, contributes favourably tothe appearance of feeding blue whales in the Perth Canyon during the summer. Article in Journal/Newspaper Blue whale Curtin University: espace Austral Journal of Marine Systems 77 1-2 21 44 |
institution |
Open Polar |
collection |
Curtin University: espace |
op_collection_id |
ftcurtin |
language |
unknown |
topic |
Leeuwin Current - Pygmy blue whales - Submarine canyon - Upwelling - Primary production - Physical oceanography - Perth Canyon - Western Australia |
spellingShingle |
Leeuwin Current - Pygmy blue whales - Submarine canyon - Upwelling - Primary production - Physical oceanography - Perth Canyon - Western Australia Rennie, Susan Hanson, C. McCauley, Robert Pattiaratchi, C. Burton, C. Bannister, J. Jenner, C. Jenner, M. Physical properties and processes in the Perth Canyon, Western Australia: Links to water column production and seasonal pygmy blue whale abundance |
topic_facet |
Leeuwin Current - Pygmy blue whales - Submarine canyon - Upwelling - Primary production - Physical oceanography - Perth Canyon - Western Australia |
description |
The oceanography of the Perth Canyon, off southwestern Australia, was examined through two major field excursions in austral spring/summer 2003/2004 combined with previous results from field analysis and numerical simulations. Water properties were used to identify water masses and vertical displacement. The field cruises and numerical simulation indicated unique circulation features of the Leeuwin Current and Undercurrent within the canyon associated with the topographic features. The input of nutrients to the euphotic zone occurred sporadically as the Leeuwin Current generally suppressed upwelling, although the Perth Canyon had increased nutrient concentrations within its rims. The distribution of chlorophyll in the surface layers indicated high spatial variability, with a prevalent deep chlorophyll (and phytoplankton biomass) maximum at ~80 m. Depth-integrated primary production within the study region ranged from 360 to 760 mg C m-2 d-1, which was on average 2.5 times higher than rates measured in continental shelf and off shorewaters north of the canyon.Aggregations of krill and other acoustic backscatter targets were concentrated near the head of the canyon at a range of depths, which may have been promoted by the circulation. The findings here are consistent with seasonal variations in wind and insolation, along with variations in the Leeuwin Current, influencing the seasonal changes and mesoscale features within the region, while the canyon promotes localised upwelling, and enhances both pelagic production and physical aggregation of plankton to attract the whales. Canyon processes must be combined with outside factors to allow upwelled nutrients to reach the photic zone. It is concluded that a combination of factors, rather than one factor alone, contributes favourably tothe appearance of feeding blue whales in the Perth Canyon during the summer. |
format |
Article in Journal/Newspaper |
author |
Rennie, Susan Hanson, C. McCauley, Robert Pattiaratchi, C. Burton, C. Bannister, J. Jenner, C. Jenner, M. |
author_facet |
Rennie, Susan Hanson, C. McCauley, Robert Pattiaratchi, C. Burton, C. Bannister, J. Jenner, C. Jenner, M. |
author_sort |
Rennie, Susan |
title |
Physical properties and processes in the Perth Canyon, Western Australia: Links to water column production and seasonal pygmy blue whale abundance |
title_short |
Physical properties and processes in the Perth Canyon, Western Australia: Links to water column production and seasonal pygmy blue whale abundance |
title_full |
Physical properties and processes in the Perth Canyon, Western Australia: Links to water column production and seasonal pygmy blue whale abundance |
title_fullStr |
Physical properties and processes in the Perth Canyon, Western Australia: Links to water column production and seasonal pygmy blue whale abundance |
title_full_unstemmed |
Physical properties and processes in the Perth Canyon, Western Australia: Links to water column production and seasonal pygmy blue whale abundance |
title_sort |
physical properties and processes in the perth canyon, western australia: links to water column production and seasonal pygmy blue whale abundance |
publisher |
Elsevier |
publishDate |
2009 |
url |
https://hdl.handle.net/20.500.11937/40847 https://doi.org/10.1016/j.jmarsys.2008.11.008 |
geographic |
Austral |
geographic_facet |
Austral |
genre |
Blue whale |
genre_facet |
Blue whale |
op_relation |
http://hdl.handle.net/20.500.11937/40847 doi:10.1016/j.jmarsys.2008.11.008 |
op_doi |
https://doi.org/20.500.11937/4084710.1016/j.jmarsys.2008.11.008 |
container_title |
Journal of Marine Systems |
container_volume |
77 |
container_issue |
1-2 |
container_start_page |
21 |
op_container_end_page |
44 |
_version_ |
1768385280691142656 |