Two canyons (Juan de Fuca and Barkley) off the west coast of Vancouver Island show
enhanced upwelling during the summer. Barkley Canyon is also a region of zooplankton
aggregation. An intensive survey was conducted to characterize their circulation, water
properties and, for Barkley, zooplankton distribution. CTD casts and zooplankton tows
were performed in 1997 around Barkley Canyon. Current meter moorings were positioned
within both canyons (Juan de Fuca in 1993 and Barkley in 1997).
The circulation in Juan de Fuca Canyon is characterized by a southeastward flow at 30
and 75 m but a northward, in-canyon flow at 200 m. The deep flow supports a strong and
consistent upwelling from May to October with a strong decrease in temperature equivalent
to a 200-m vertical displacement. The northward-flowing California Undercurrent
is found to have no significant influence on the upwelling.
In Barkley Canyon, there is a weaker upwelling signal that nonetheless explains an
important variance in the CTD data. Isopleths upwell towards the head of the canyon
and dome over it near the surface. This implies that the influence of the canyon reaches
shallower depths than in Astoria Canyon, for example. The circulation of the canyon is
assessed from the mooring data: the flow bends over the canyon at 150 m, with a possible
cyclonic eddy at the head, while the current is mainly cyclonic at depth. Some in-canyon
flow events are observed, which result in moderate upwelling.
Zooplankton are found to aggregate along the walls near the head and mouth of
Barkley Canyon with different distribution patterns according to the species' vertical
and spatial preferences. Interaction with the circulation, especially the deep cyclonic
flow, seems to play an important role in this aggregation.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:BVAU.2429/8347 |
| Date | 11 1900 |
| Creators | Vindeirinho, Carine |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Relation | UBC Retrospective Theses Digitization Project [http://www.library.ubc.ca/archives/retro_theses/] |
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