A Winter Incursion of Slope Water on the Scotian Shelf

1953 ◽  
Vol 10 (3) ◽  
pp. 148-153 ◽  
Author(s):  
H. B. Hachey
Keyword(s):  
Continental Shelf ◽  
Scotian Shelf ◽  
Submarine Channel

A sub-surface incursion of slope water, of temperatures as high as 12.0 °C., over an area in the vicinity of the submarine channel entering the Scotian Gulf, took place in the winter of 1949. This is the first occasion on the Scotian Shelf where the slope water of such temperatures has been observed north of the edge of the continental shelf.

scholarly journals Seasonal trends and phenology shifts in sea surface temperature on the North American northeastern continental shelf

Elem Sci Anth ◽  
2017 ◽  
Vol 5 ◽  
Author(s):  
Andrew C. Thomas ◽  
Andrew J. Pershing ◽  
Kevin D. Friedland ◽  
Janet A. Nye ◽  
Katherine E. Mills ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Continental Shelf ◽  
Sea Surface Temperature ◽  
North American ◽  
Gulf Of Maine ◽  
Sea Surface ◽  
Scotian Shelf ◽  
Seasonal Differences ◽  
Study Region ◽  
The North

The northeastern North American continental shelf from Cape Hatteras to the Scotian Shelf is a region of globally extreme positive trends in sea surface temperature (SST). Here, a 33-year (1982–2014) time series of daily satellite SST data was used to quantify and map spatial patterns in SST trends and phenology over this shelf. Strongest trends are over the Scotian Shelf (>0.6°C decade–1) and Gulf of Maine (>0.4°C decade–1) with weaker trends over the inner Mid-Atlantic Bight (~0.3°C decade–1). Winter (January–April) trends are relatively weak, and even negative in some areas; early summer (May–June) trends are positive everywhere, and later summer (July–September) trends are strongest (~1.0°C decade–1). These seasonal differences shift the phenology of many metrics of the SST cycle. The yearday on which specific temperature thresholds (8° and 12°C) are reached in spring trends earlier, most strongly over the Scotian Shelf and Gulf of Maine (~ –0.5 days year–1). Three metrics defining the warmest summer period show significant trends towards earlier summer starts, later summer ends and longer summer duration over the entire study region. Trends in start and end dates are strongest (~1 day year–1) over the Gulf of Maine and Scotian Shelf. Trends in increased summer duration are >2.0 days year–1 in parts of the Gulf of Maine. Regression analyses show that phenology trends have regionally varying links to the North Atlantic Oscillation, to local spring and summer atmospheric pressure and air temperature and to Gulf Stream position. For effective monitoring and management of dynamically heterogeneous shelf regions, the results highlight the need to quantify spatial and seasonal differences in SST trends as well as trends in SST phenology, each of which likely has implications for the ecological functioning of the shelf.

scholarly journals A photographic atlas of the eastern Canadian Continental Shelf: Scotian Shelf, Grand Banks of Newfoundland

1989 ◽  
Author(s):  
P Lawrence ◽  
K W Strong ◽  
P Pocklington ◽  
P L Stewart ◽  
G B J Fader
Keyword(s):  
Continental Shelf ◽  
Scotian Shelf ◽  
Grand Banks

scholarly journals Water masses and nutrient sources to the Gulf of Maine

2015 ◽  
Vol 73 (3) ◽  
pp. 93-122 ◽  
Author(s):  
David W. Townsend ◽  
Neal R. Pettigrew ◽  
Maura A. Thomas ◽  
Mark G. Neary ◽  
Dennis J. McGillicuddy ◽  
...  
Keyword(s):  
Continental Shelf ◽  
Deep Water ◽  
Gulf Of Maine ◽  
Volume Transport ◽  
Water Masses ◽  
Scotian Shelf ◽  
Nutrient Sources ◽  
The North ◽  
Freshwater Fluxes ◽  
The North Atlantic Oscillation

The Gulf of Maine, a semienclosed basin on the continental shelf of the northwest Atlantic Ocean, is fed by surface and deep water flows from outside the gulf: Scotian Shelf Water (SSW) from the Nova Scotian shelf that enters the gulf at the surface and slope water that enters at depth and along the bottom through the Northeast Channel. There are two distinct types of slope water, Labrador Slope Water (LSW) and Warm Slope Water (WSW); it is these deep water masses that are the major source of dissolved inorganic nutrients to the gulf. It has been known for some time that the volume inflow of slope waters of either type to the Gulf of Maine is variable, that it covaries with the magnitude of inflowing SSW, and that periods of greater inflows of SSW have become more frequent in recent years, accompanied by reduced slope water inflows. We present here analyses of a 10-year record of data collected by moored sensors in Jordan Basin in the interior Gulf of Maine, and in the Northeast Channel, along with recent and historical hydrographic and nutrient data that help reveal the nature of SSW and slope water inflows. We show that proportional inflows of nutrient-rich slope waters and nutrient-poor SSWs alternate episodically with one another on timescales of months to several years, creating a variable nutrient field on which the biological productivities of the Gulf of Maine and Georges Bank depend. Unlike decades past, more recent inflows of slope waters of either type do not appear to be correlated with the North Atlantic Oscillation (NAO), which had been shown earlier to influence the relative proportions of the two types of slope waters that enter the gulf, WSW and LSW. We suggest that of greater importance than the NAO in recent years are recent increases in freshwater fluxes to the Labrador Sea, which may intensify the volume transport of the inshore, continental shelf limb of the Labrador Current and its continuation as the Nova Scotia Current. The result is more frequent, episodic influxes of colder, fresher, less dense, and low-nutrient SSW into the Gulf of Maine and concomitant reductions in the inflow of deep, nutrient-rich slope waters. We also discuss evidence that modified Gulf Stream ring water may have penetrated to Jordan Basin in the summer of 2013.

Dispersal of American Lobsters, Homarus americanus, Tagged Off Southern Nova Scotia

1989 ◽  
Vol 46 (11) ◽  
pp. 1842-1844 ◽  
Author(s):  
Alan Campbell
Keyword(s):  
Nova Scotia ◽  
Continental Shelf ◽  
Continental Slope ◽  
Gulf Of Maine ◽  
Homarus Americanus ◽  
Georges Bank ◽  
Scotian Shelf ◽  
Long Distance ◽  
German Bank ◽  
Long Distance Movement

Of the 5281 American lobsters (Homarus americanus) tagged and released off McNutt Island, South Nova Scotia, during 1983–87, 15.8% were captured within 3 yr of release. Although most immature (99%) and mature (86%) lobsters were caught < 18.5 km from release, mature lobsters moved a greater mean distance (25.8 km) than immature lobsters (3.6 km). Of the lobsters that moved > 30 km eight moved south to the continental slope near Browns Bank and 11 moved west of Cape Sable to the inshore areas of southwestern Nova Scotia, the midshore area of German Bank and offshore to Browns Bank and Georges Bank. This and other studies of tagged lobsters indicate that there is some movement of lobsters east and west of the Cape Sable area, the southern tip of Nova Scotia, suggesting some mixing between lobster stocks off eastern Nova Scotia and southwestern Nova Scotia. The long distance movement and mixing of mature lobsters suggests that attempts to use tagging information in locating biological boundaries between lobster stocks in the Gulf of Maine, adjoining Continental Shelf, Scotian Shelf and inshore areas of southwestern Nova Scotia and southern end of eastern Nova Scotia may be a difficult task.

scholarly journals Effect of channel tributaries on the evolution of submarine channel confluences (Espírito Santo Basin, SE Brazil)

2019 ◽  
Vol 132 (1-2) ◽  
pp. 263-272 ◽  
Author(s):  
Yongpeng Qin ◽  
Tiago M. Alves ◽  
José Antonio Constantine ◽  
Davide Gamboa ◽  
Shiguo Wu
Keyword(s):  
Continental Shelf ◽  
Main Channel ◽  
Turbidity Currents ◽  
Lateral Migration ◽  
Sediment Sources ◽  
The West ◽  
Multiple Channel ◽  
Channel Bend ◽  
Submarine Channel ◽  
Se Brazil

AbstractConfluences are geomorphologic features fed by distinct channel tributaries that record the contribution of multiple sediment sources. They are key features of both fluvial and submarine channels in geomorphologic and sedimentologic terms. Here, we use high-quality three-dimensional seismic data from SE Brazil to document the response of a submarine channel confluence to turbidity currents originating from a tributary. The studied channel system consists of a west tributary, an east tributary, and a postconfluence channel, with the last two comprising the main channel at present. Downstream from the confluence, changes in planform morphology and architecture were found due to the effect of turbidity currents sourced from the west tributary channel. A channel bend in the main channel curved toward the west when it was first formed but later curved toward the east, and so remains until the present day. This process led to the migration of the confluence point ∼500 m to the east, and changed the bed morphology from discordant (where the beds of tributaries and main channels meet at an unequal depth) to concordant (where the beds of tributaries and main channels meet at approximately the same depth). In addition to the channel bend near the confluence, two other bends further downstream recorded significant changes with time, increasing channel sinuosity from 1.11 to 1.72. These three channel bends near the confluence accumulated a large volume of sediment at their inner banks, generating depositional bars. Multiple channel forms within the depositional bars indicate the occurrence of large-scale lateral migration near the confluence. Hence, turbidity currents from the west tributary are shown to influence the submarine channel by promoting lateral channel migration, confluence migration, increases in channel sinuosity, and the formation of large depositional bars. These variations near the confluence reveal a change in tributary activity and a shift in sediment sources from east to west on the continental shelf. Such a shift suggests variations in sedimentary processes on the continental shelf probably due to avulsions on Doce River Delta.

Clostridium botulinum in Sediments from the Canadian Atlantic Seaboard

1972 ◽  
Vol 29 (4) ◽  
pp. 443-446 ◽  
Author(s):  
R. A. Laycock ◽  
A. A. Longard
Keyword(s):  
Nova Scotia ◽  
Continental Shelf ◽  
Clostridium Botulinum ◽  
High Concentration ◽  
Scotian Shelf ◽  
Low Concentration ◽  
Atlantic Seaboard ◽  
High Incidence ◽  
Type C ◽  
Northeast Coast

The presence of Clostridium botulinum types B, C, and E has been detected off the coast of Nova Scotia. Whereas types B and E were found only in low concentration on the Scotian Shelf, localized areas of high concentration of type C were found inshore in the Halifax–Dartmouth area and offshore in the deeper waters of Emerald Basin and the edge of the Shelf. Type E only was found off the coast of Newfoundland with a high incidence of the organism as far as 150 miles off the northeast coast. In general, C. botulinum appeared to be absent from the shallower bank areas but present in the deeper waters within and bordering upon the Continental Shelf.

Ichthyoplankton Associated with a Warm Core Ring off the Scotiars Shelf

1984 ◽  
Vol 41 (2) ◽  
pp. 294-303 ◽  
Author(s):  
J. S. Wroblewski ◽  
Jerry Cheney
Keyword(s):  
Continental Shelf ◽  
Shelf Break ◽  
Shelf Water ◽  
Scotian Shelf ◽  
Larval Drift ◽  
Warm Core ◽  
Warm Core Ring ◽  
Shelf Slope ◽  
Continental Shelf Break ◽  
Upper Slope

A warm core ring and adjacent waters off the Scotian Shelf in June 1982 contained substantial numbers of larval and juvenile white hake, Urophycis tenuis, as far as 140 km seaward of the continental shelf break. The warm core ring, designated 81-G, had entrained shelf water on several occasions before the shipboard observations were made. We suggest that the ring contributed to the offshore advection of these fish, which probably were spawned on the continental shelf or upper slope. Warm core rings can disrupt the usual larval drift pattern of shelf–slope fishes and thereby affect recruitment. Larvae and juveniles of several species of tropical–subtropical fishes found in ring 81-G have been reported previously as rare specimens in ichthyoplankton surveys on the Scotian Shelf. Our observations support the hypothesis that warm core rings can be a mechanism for transport of these expatriated fishes onto the shelf.

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