scholarly journals Densité agricole et charge humaine des terroirs : Essai méthodologique avec application à quatre comtés au sud de l’estuaire du Saint-Laurent

2005 ◽  
Vol 9 (17) ◽  
pp. 11-23
Author(s):  
Jean Raveneau
Keyword(s):  
Physical Environment ◽  
Population Based ◽  
Population Pressure ◽  
Direct Proportion ◽  
Lawrence Estuary ◽  
Real Population ◽  
Two Factors ◽  
Part Time ◽  
South Shore ◽  
St Lawrence Estuary

The density of agricultural population based on cleared land does not necessarily express the real population pressure in a given agricultural region. Two factors can upset the significance of this measure of density : (1) differences in the intensity of exploitation within a single territory ; and (2), variations in the proportion of part-time farmers. The author bas developed an index of the pressure of population on the land by making various calculations for jour counties in Québec, on the south shore of the St. Lawrence estuary. He bas found that the population pressure on the land varies in nearly direct proportion to the agricultural density based on cleared land, in spite of the lack of uniformity of the physical environment in question. The author concludes that the agricultural density retains its validity for expressing the population pressure on the land.

scholarly journals Visibility of St Lawrence belugas to aerial photography, estimated by direct observation

2002 ◽  
Vol 4 ◽  
pp. 259 ◽  
Author(s):  
Michael CS Kingsley ◽  
Isabelle Gauthier
Keyword(s):  
Water Clarity ◽  
Population Based ◽  
Aerial Survey ◽  
Aerial Photographs ◽  
Delphinapterus Leucas ◽  
Secchi Disk ◽  
Lawrence Estuary ◽  
Summer Range ◽  
Different Depths ◽  
St Lawrence Estuary

The depleted population of belugas (Delphinapterus leucas) inhabiting the St Lawrence estuary, Canada, was monitored by periodic photographic aerial surveys. In order to correct counts made on aerial survey film and to obtain an estimate of the true size of the population, the diving behaviour and the visibility from the air of these animals was studied. A Secchi-disk turbidity survey in the belugas’ summer range showed that water clarity varied between 1.5 m and 11.6 m. By studying aerial photographs of sheet-plastic models of belugas that had been sunk to different depths below the surface, we found that models of white adults could be seen down to about the same depth as a Secchi disk, but no deeper. Smaller models of dark-grey juveniles could only be seen down to about 50% of Secchi-disk depth. By observing groups of belugas from a hovering helicopter and recording their disappearances and re-appearances, it was found that they were visible for 44.3% of the time, and that an appropriate correction for single photographs would be to multiply the photographic count by about 222% (SE 20%). For surveys in which there was overlap between adjacent frames, the estimated correction would be 209% (SE 16%). This correction factor was slightly conservative and gave an estimate of the true size of the population, based on a single survey, of 1,202 belugas (SE 189) in 1997. An estimate for 1997 based on smoothing 5 surveys 1988–1997 was 1,238 (SE 119).

scholarly journals La mer de Goldthwait au Québec

2010 ◽  
Vol 31 (1-2) ◽  
pp. 61-80 ◽  
Author(s):  
Jean-Claude Dionne
Keyword(s):  
Quebec City ◽  
The South ◽  
Lawrence Estuary ◽  
Marine Invasion ◽  
North Shore ◽  
The North ◽  
Upper Limit ◽  
South Shore ◽  
Anticosti Island ◽  
St Lawrence Estuary

The Goldthwait Sea is defined as the late- and post-Glacial marine invasion in the St. Lawrence Estuary and Gulf east of Québec City. In Québec, this sea has submerged an area of about 25 000 km2. The largest areas submerged are the north shore of the St. Lawrence between Les Escoumins and Blanc-Sablon, the south shore between Levis and Tourelles, and the Anticosti Island. The upper limit of the Goldthwait Sea varies from place to place. The Goldthwait Sea began 14 000 years ago and land emergence is still in progress, since the pre-Wisconsin marine level has not been recovered yet. For a better chronology, this long interval needs to be subdivided. Three main periods have been recognized: Goldthwaitian I, II and III. However, a geographical subdivision is also needed. Numerous shorelines were observed at various elevations throughout the area formely submerged by the Goldthwait Sea. However, only a few shorelines are well developed and extensive, and correlations between former shorelines are difficult to establish. Only three levels are widespead and common to the Estuary and parts of the Gulf. The isostatic recovery has been rapid during the first three thousand years after déglaciation of the area: about 75%.

The food and feeding of common eiders in the St. Lawrence estuary in summer

1974 ◽  
Vol 52 (3) ◽  
pp. 319-334 ◽  
Author(s):  
M. Cantin ◽  
J. Bédard ◽  
H. Milne
Keyword(s):  
Intertidal Zone ◽  
Maximum Growth ◽  
Somateria Mollissima ◽  
Lawrence Estuary ◽  
Common Eiders ◽  
Feeding Activities ◽  
Food And Feeding ◽  
South Shore ◽  
Natural Foods ◽  
St Lawrence Estuary

The study was conducted in the St. Lawrence estuary during 1969 and 1970. The food abundance in the intertidal zone was measured in four Sampling stations located on the south shore of the river; the measurements revealed that over 95% of the available food of the common eider (Somateria mollissima) consisted of Littorina spp., Mytilus edulis, and Gammarus oceanicus. Both adult and young birds showed a distinct rhythm of feeding activities associated with tidal level. During the prenesting period, herring eggs and Nereis virens made up most of the food of adult common eiders. When accompanying ducklings, females ate mostly Littorina spp. and amphipods. Littorina spp. made up between 30 and 97% of the diet of the ducklings, the importance of this gastropod growing with age of the bird. Energy requirements during maximum growth were evaluated at about 460 kcal/bird per day on ducklings (age 54 days) fed natural foods, while between week 3 and week 8 it stood at about 520 kcal/bird per day in ducklings fed "turkey starter." These figures were used to assess the importance of the food removed by the eiders from the intertidal zone during the summer. We conclude that between 10 and 30% (according to the area) of the standing-crop biomass of Littorina alone (in July) is removed by the ducklings and the females accompanying them. At various moments through the season, these birds remove between 40 and 100 metric tons of mollusks per day from the intertidal zone.

scholarly journals TIDAL SEDIMENTATION IN GROS-CACOUNA HARBOR

1978 ◽  
Vol 1 (16) ◽  
pp. 120 ◽  
Author(s):  
Georges Drapeau ◽  
Guy Fortin
Keyword(s):  
Suspended Sediment ◽  
Suspended Sediments ◽  
Suspended Sediment Transport ◽  
Lawrence Estuary ◽  
Seismic Profiling ◽  
Reflection Seismic ◽  
High Turbidity ◽  
South Shore ◽  
Bottom Sampling ◽  
St Lawrence Estuary

The harbor of Gros-Cacouna on the South shore of the St. Lawrence Estuary has been silting at the rate of 31 cm/yr. since it was dredged at the depth of 14 meters in 1968. Measurements of temperature, salinity, turbidity, current speed and direction were carried out as well as bottom sampling and reflection seismic profiling. A model of suspended sediment transport combines the tidal volumes and the current profiles at the harbor entrance. During a period of high turbidity (Spring) in the St.Lawrence Estuary, 54.2 tons of suspended sediments entered the harbor during the flood phase, while 41.1 tons were carried out during the ebb phase of a semi-diurnal tide, leaving 13.1 tons of sediments in the harbor. The transfer coefficient is 0.24 indicating that one quarter of the suspended sediment load settles in the harbor during one tidal cycle. In September, the turbidity is low in the Estuary and the suspended sediment budget in the harbor is 4 times smaller but the ratio of deposited sediments versus the total quantity of sediments transported in suspension is the same.

Mud Cracks and Polygons on Ice Push Ridges, in Tidal Flats of the St. Lawrence Estuary

1974 ◽  
Vol 11 (3) ◽  
pp. 489-494 ◽  
Author(s):  
Jean-Claude Dionne
Keyword(s):  
Water Level ◽  
Tidal Flats ◽  
The South ◽  
Lawrence Estuary ◽  
Waves And Currents ◽  
South Shore ◽  
Break Up ◽  
St Lawrence Estuary

Mud cracks and polygons form during summer in tidal flats of the south shore of the St. Lawrence Estuary. They occur near mean low water level at the top surface of ice push mud ridges formed during winter and break-up. They are a source of mud clasts which settle in the surroundings when carried away by waves and currents.

Above- and below-ground macrophyte production in Scirpus tidal marshes of the St. Lawrence estuary, Quebec

1988 ◽  
Vol 66 (5) ◽  
pp. 955-962 ◽  
Author(s):  
Jean-François Giroux ◽  
Jean Bédard
Keyword(s):  
Standing Crop ◽  
River Estuary ◽  
Dry Mass ◽  
Tidal Marshes ◽  
Lawrence Estuary ◽  
Aboveground Production ◽  
History Of ◽  
Below Ground ◽  
South Shore ◽  
St Lawrence Estuary

Above- and below-ground standing crops as well as primary production of several macrophytes were estimated in Scirpus marshes along the south shore of the St. Lawrence River estuary in Quebec. Aboveground standing crop was measured by clipping vegetation, while belowground standing crop was estimated by soil coring. Seasonal variation of live and dead standing crops was first determined for different plant species. The root:shoot mass ratio was then examined and related to the life history of each species. Total aboveground production varied from 74 to 627 g ash-free dry mass∙m−2∙year−1 among different plant communities, whereas belowground production was lower, with estimates varying between 38 and 244 g∙m−2∙year−1. Production was lower along the St. Lawrence estuary than in other types of marshes located farther south.

Use of Variation in Biological Characters for the Classification of Anadromous Rainbow Smelt (Osmerus mordax) Groups

1983 ◽  
Vol 40 (6) ◽  
pp. 718-727 ◽  
Author(s):  
A. Fréchet ◽  
J. J. Dodson ◽  
H. Powles
Keyword(s):  
Open Water ◽  
Growth Patterns ◽  
Osmerus Mordax ◽  
Rainbow Smelt ◽  
Lawrence Estuary ◽  
Saguenay Fjord ◽  
South Shore ◽  
Lower North Shore ◽  
St Lawrence Estuary

Analysis of meristics, growth patterns, and fecundity to somatic weight relationships of spawning anadromous rainbow smelt (Osmerus mordax) in Quebec waters demonstrated the existence of three geographical groups (Chaleur Bay, south shore of the St. Lawrence Estuary, and Saguenay Fjord). Although homing to spawning rivers does not appear to occur, the degree of heterogeneity of spawning smelt of different geographical areas is less at the extremes of their Quebec distribution. Classification of smelt from the commercial fishery catch indicates limited mixing of these groups during open-water migration. The existence of a fourth group is suggested by classification analysis of smelt caught along the lower north shore of the St. Lawrence Estuary.

scholarly journals Formes de corrosion littorale, côte sud du Saint-Laurent

2005 ◽  
Vol 11 (23) ◽  
pp. 379-395 ◽  
Author(s):  
Jean-Claude Dionne
Keyword(s):  
Geographical Distribution ◽  
Rocky Shores ◽  
The South ◽  
Cold Regions ◽  
Lawrence Estuary ◽  
South Shore ◽  
St Lawrence Estuary ◽  
First Time ◽  
Extensive Bibliography

Corrosion features were observed on the South Shore of the Maritime St. Lawrence Estuary, in conglomerate, limestone, sandstone, shale and cristalline boulders, and are here described for the first time. An attempt to classify these minor features characteristic of rocky shores is made and an extensive bibliography is given. An effort should be made to get more information on the geographical distribution of coastal corrosion forms on non calcareous rocks in cold regions.

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