Biological and Hydrographical Evidence for Pacific Equatorial Water on the Continental Shelf North of Vancouver Island, British Columbia

1982 ◽  
Vol 39 (5) ◽  
pp. 660-667 ◽  
Author(s):  
Grant A. Gardner
Keyword(s):  
British Columbia ◽  
Continental Shelf ◽  
Deep Water ◽  
Water Mass ◽  
Fish Communities ◽  
Vancouver Island ◽  
Zooplankton Species ◽  
Regular Event

Data from two cruises in April and November 1977 indicate the presence of Pacific equatorial water on the continental shelf north of Vancouver Island. Water with the general temperature/salinity characteristics of the California Undercurrent was found on the shelf at both times. Equatorial water formed ~30% of this deep-water mass, with Pacific subarctic water making up the remainder. Evidence for the presence of equatorial water was supported by the occurrence in the study area of six normally subtropical zooplankton species: Mesocalanus tenuicornis, Lophothrix frontalis, Candacia bipinnata, Lucicutia flavicornis, Heterostylites longicornis, and Pleuromamma xiphias. An increase in the proportion of equatorial water on the shelf, and a concomitant extension of the limits of distribution of oceanic zooplankters in the study area, both infer an intrustion of deep water onto the shelf during the period between the two cruises. This intrusion is probably a regular event with important ramifications for the zooplankton and fish communities of the area.Key words: continental shelf, British Columbia, hydrography, California Undercurrent, zooplankton

Late Pleistocene history and geomorphology, southwestern Vancouver Island, British Columbia

1979 ◽  
Vol 16 (9) ◽  
pp. 1645-1657 ◽  
Author(s):  
Neville F. Alley ◽  
Steven C. Chatwin
Keyword(s):  
British Columbia ◽  
Continental Shelf ◽  
Late Pleistocene ◽  
Vancouver Island ◽  
Glacial Lakes ◽  
Small Lakes ◽  
Strait Of Georgia ◽  
Coast Mountains ◽  
Juan De Fuca ◽  
Juan De Fuca Strait

The major Pleistocene deposits and landforms on southwestern Vancouver Island are the result of the Late Wisconsin (Fraser) Glaciation. Cordilleran glaciers formed in the Vancouver Island Mountains and in the Coast Mountains had advanced down Strait of Georgia to southeastern Vancouver Island after 19 000 years BP. The ice split into the Puget and Juan de Fuca lobes, the latter damming small lakes along the southwestern coastal slope of the island. During the maximum of the glaciation (Vashon Stade), southern Vancouver Island lay completely under the cover of an ice-sheet which flowed in a south-southwesterly direction across Juan de Fuca Strait, eventually terminating on the edge of the continental shelf. Deglaciation was by downwasting during which ice thinned into major valleys and the strait. Most upland areas were free of ice down to an elevation of 400 m by before 13 000 years BP. A possible glacier standstill and (or) resurgence occurred along Juan de Fuca Strait and in some interior upland valleys before deglaciation was complete. Glacial lakes occupied major valleys during later stages of deglaciation.

scholarly journals Water Mass Characteristics and Distribution Adjacent to Larsen C Ice Shelf, Antarctica

2020 ◽  
Author(s):  
Katherine Hutchinson ◽  
Julie Deshayes ◽  
Jean-Baptiste Sallee ◽  
Julian Dowdeswell ◽  
Casimir de Lavergne ◽  
...  
Keyword(s):  
Continental Shelf ◽  
Ocean Circulation ◽  
Deep Water ◽  
Water Mass ◽  
Heat Content ◽  
Weddell Sea ◽  
Global Ocean ◽  
Spatial And Temporal Variability ◽  
Ice Shelf ◽  
Shed Light

<p>The physical oceanographic environment, water mass mixing and transformation in the area adjacent to Larsen C Ice Shelf (LCIS) are investigated using hydrographic data collected during the Weddell Sea Expedition 2019. The results shed light on the ocean conditions adjacent to a thinning LCIS, on a continental shelf that is a source region for the globally important water mass, Weddell Sea Deep Water (WSDW). Modified Weddell Deep Water (MWDW), a comparatively warmer water mass of circumpolar origin, is identified on the continental shelf and is observed to mix with local shelf waters, such as Ice Shelf Water (ISW), which is a precursor of WSDW. Oxygen measurements enable the use of a linear mixing model to quantify contributions from source waters revealing high levels of mixing in the area, with much spatial and temporal variability. Heat content anomalies indicate an introduction of heat, presumed to be associated with MWDW, into the area via Jason Trough. Furthermore, candidate parent sources for ISW are identified in the region, indicating the potential for the circulation of continental shelf waters into the ice shelf cavity. This highlights the possibility that offshore climate signals are conveyed under LCIS. ISW is observed within Jason Trough, likely exiting the sub-ice shelf cavity en route to the Slope Current. This onshore-offshore flux of water masses links the region of the Weddell Sea adjacent to northern LCIS to global ocean circulation and Bottom Water characteristics via its contribution to ISW and hence WSDW properties. </p><p>What remains to be clarified is whether MWDW found in Jason Trough has a direct impact on basal melting and thus thinning of LCIS. More observations are required to investigate this, in particular direct observations of ocean circulation in Jason Trough and underneath LCIS. Modelling experiments could also shed light on this, and so preliminary results based on NEMO global simulations explicitly representing the circulation in under-ice shelf seas, will be presented. </p>

Distribution of Nitzschia pungens in Coastal Waters of British Columbia

1991 ◽  
Vol 48 (6) ◽  
pp. 960-967 ◽  
Author(s):  
J. R. Forbes ◽  
K. L. Denman
Keyword(s):  
British Columbia ◽  
Continental Shelf ◽  
Coastal Waters ◽  
Domoic Acid ◽  
Pacific Coast ◽  
Minor Component ◽  
Vancouver Island ◽  
Large Diatom ◽  
A Minor ◽  
Nitzschia Pungens

Concern about the potential for contamination of Pacific coast molluscan shellfish by domoic acid prompted us to review the distribution of Nitzschia pungens in coastal waters of British Columbia. From 1980 to 1988, N. pungens occurred throughout waters of the continental shelf, most frequently as a minor component of the large diatom aggregations observed off southwest Vancouver Island during July and August. The species was less common in the Strait of Georgia and north of Vancouver Island, but interannual variability in distribution and abundance was considerable. Maximum concentrations recorded were 106 cells∙L−1 in Hecate Strait in July 1983 and 5 × 105 cells∙L−1 off southwest Vancouver Island in August 1986. Discrimination of presence or absence on the basis of existing environmental variables produced mixed results, but has potential. Scanning electron microscopy showed that both N. pungens f. pungens and N. pungens f. multiseries (the latter being implicated in the contamination of shellfish in Atlantic Canada) occur in British Columbia. It remains to be shown whether N. pungens produces domoic acid in Pacific coast waters and whether the high abundances observed over the continental shelf also occur near shore.

scholarly journals Surficial geology of the Vancouver Island continental shelf, Scott Islands to Nootka Sound, offshore British Columbia

1992 ◽  
Author(s):  
K W Conway ◽  
J V Barrie ◽  
B D Bornhold
Keyword(s):  
British Columbia ◽  
Continental Shelf ◽  
Vancouver Island ◽  
Surficial Geology

scholarly journals Continental Shelf and Slope Studies, northwestern Vancouver Island, British Columbia

1971 ◽  
Author(s):  
R D Macdonald ◽  
J W Murray ◽  
D L Tiffin
Keyword(s):  
British Columbia ◽  
Continental Shelf ◽  
Vancouver Island

Results from Tagging Experiments on a Spawning Stock of Petrale Sole, Eopsetta jordani (Lockington)

1957 ◽  
Vol 14 (6) ◽  
pp. 953-974 ◽  
Author(s):  
Dayton L. Alverson ◽  
Bruce M. Chatwin
Keyword(s):  
British Columbia ◽  
Deep Water ◽  
Historical Development ◽  
Vancouver Island ◽  
Early Spring ◽  
Northwest Coast ◽  
The West ◽  
Trawl Fishing ◽  
Spawning Stock ◽  
Island Coast

A review is made of the historical development of the petrale sole (Eopsetta jordani) fishery off the State of Washington (U.S.A.) and British Columbia (Canada), with statistical records of catches. A shift in recent years in the depth of trawl fishing from shallow water over the continental shelf to deeper water on the continental slope resulted in the discovery of dense concentrations of petrale sole at depths from 170–250 fathoms off the west coast of Vancouver Island. Tagging was carried out in the early spring of 1954 and 1955 on these deep-water stocks. Recoveries to May 30, 1956, from some 3,800 tags released showed that the male segment of the stock moved north and inshore along the Vancouver Island coast after spawning and at least part of the stock moved eventually into Hecate Strait, British Columbia. The tagged population contributed mainly to the fisheries adjacent to the northwest coast of Vancouver Island and in the Queen Charlotte Sound area. Subsequent recoveries from the Esteban Deep during the spawning seasons of 1955 and 1956 and the absence of the stock on this ground at other seasons, strongly suggest a homing tendency for this species. A discussion is given of the possible directive factors in the spawning migration. However, at the present time the actual factors involved remain unknown.

Glaciation and post-glacial history of the continental shelf off southwestern Vancouver Island, British Columbia

1982 ◽  
Vol 48 (3-4) ◽  
pp. 285-319 ◽  
Author(s):  
Richard H. Herzer ◽  
Brian D. Bornhold
Keyword(s):  
British Columbia ◽  
Continental Shelf ◽  
Vancouver Island ◽  
Glacial History ◽  
History Of
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