Nutrient Distribution in the St. Lawrence Estuary

1977 ◽  
Vol 34 (11) ◽  
pp. 2104-2116 ◽  
Author(s):  
Paul Greisman ◽  
Grant Ingram
Keyword(s):  
Intermediate Layer ◽  
Internal Tide ◽  
Horizontal Distribution ◽  
Estuarine System ◽  
Nutrient Distribution ◽  
Surface Distribution ◽  
Lawrence Estuary ◽  
Freshwater Source ◽  
St Lawrence Estuary ◽  
St Lawrence River

The horizontal distribution of nutrients in the St. Lawrence estuary during early July of 1975 is presented. The major sources of nutrients to the estuarine system appeared to be from the St. Lawrence River and the intermediate layer of the Laurentian Channel. By the assumption of simple mixing and conservation, the surface distribution of nutrients has been calculated. Differences between the calculated and observed values may be attributable to consumption, variability of the freshwater source and of the internal tide amplitude. Key words: nutrient distribution, estuarine circulation, mixing

A biophysical model of the interaction between vertical migration of crustacean zooplankton and circulation in the Lower St. Lawrence Estuary

1999 ◽  
Vol 56 (12) ◽  
pp. 2420-2432 ◽  
Author(s):  
Bruno A Zakardjian ◽  
Jeffrey A Runge ◽  
Stephane Plourde ◽  
Yves Gratton
Keyword(s):  
Population Dynamics ◽  
Vertical Migration ◽  
Horizontal Distribution ◽  
Calanus Finmarchicus ◽  
Biophysical Model ◽  
Crustacean Zooplankton ◽  
Simple Formulation ◽  
Lawrence Estuary ◽  
Circulation Patterns ◽  
St Lawrence Estuary

As an essential step in modeling the influence of circulation on the population dynamics of marine planktonic copepods, we define a simple formulation of swimming behavior that can be used in both Eulerian and Lagrangian models. This formulation forces aggregation of the population toward a preferential depth and can be stage specific and time varying, thus allowing description of either diurnal or seasonal vertical migration. We use the formulation to examine the interaction between the circulation and vertical distribution in controlling horizontal distribution of the common planktonic copepod Calanus finmarchicus in the Lower St. Lawrence Estuary, Canada. We first introduce diel migration into a simple one-dimensional model and then into a model of residual two-dimensional circulation patterns representative of conditions encountered in the Lower St. Lawrence Estuary. Results from the latter indicate that interactions between circulation and stage-specific swimming behaviors are the main mechanisms for aggregation of planktonic crustaceans at the head of the Laurentian Channel and highlight the implications of flushing of the surface-dwelling young stages for the population dynamics of C. finmarchicus in the Lower St. Lawrence Estuary.

Dispersion and Retention of Anadromous Rainbow Smelt (Osmerus mordax) Larvae in the Middle Estuary of the St. Lawrence River

1985 ◽  
Vol 42 (2) ◽  
pp. 332-341 ◽  
Author(s):  
Patrick Quellet ◽  
Julian J. Dodson
Keyword(s):  
Water Mass ◽  
High Tide ◽  
Horizontal Distribution ◽  
Circulation System ◽  
Larval Abundance ◽  
Osmerus Mordax ◽  
Rainbow Smelt ◽  
Lawrence Estuary ◽  
Middle Estuary ◽  
St Lawrence River

The vertical and horizontal distribution of anadromous rainbow smelt (Osmerus mordax) larvae from hatching in their natal river to their occupation of nursery areas in the middle estuary of the St. Lawrence River was documented to describe the mechanism responsible for the retention of smelt larvae in this area. Peaks of larval abundance observed downstream of the spawning grounds indicate a 24-h periodicity in hatching and the introduction of larvae into the riverine circulation. No retention of larvae was observed between the spawning ground and the downstream portion of the natal river. Our evidence indicates daytime accumulation of larvae at the mouth of the natal river, possibly resulting from the negative phototaxis exhibited by small smelt larvae. Patches of smelt larvae were incorporated into the St. Lawrence estuarine water mass once every 24 h at night following high tide. The subsequent downstream transport of larvae in the St. Lawrence estuary appears slower than the advection of the water mass due to the tendency of larvae to remain deeper in the water column during ebb tides and to concentrate near the surface during flood tides. Smelt larvae are transported from the south shore to the partially mixed northern portion of the middle estuary which represents the principal zone of larval smelt accumulation. We propose that the vertical displacements exhibited by smelt larvae in combination with the two-layer circulation system of the northern middle estuary results in the retention of smelt larvae in this region.

Le Panache du Saguenay

1983 ◽  
Vol 40 (1) ◽  
pp. 52-60 ◽  
Author(s):  
J. Lebel ◽  
E. Pelletier ◽  
M. Bergeron ◽  
N. Belzile ◽  
G. Marquis
Keyword(s):  
Surface Layer ◽  
Deep Water ◽  
High Tide ◽  
Lawrence Estuary ◽  
Fresh Waters ◽  
Saguenay Fjord ◽  
Region Data ◽  
Saguenay River ◽  
St Lawrence Estuary ◽  
St Lawrence River

The large difference between the alkalinity of the fresh waters of the St. Lawrence River (1.475 mmol∙kg−1) and the Saguenay River (0.134 mmol∙kg−1) was used to locate the region on the St. Lawrence estuary which is under the influence of the Saguenay River. This method has the advantage over classical measurements such as salinity and temperature that it is independent of the upwelling of deep water in this region. Data was obtained in the St. Lawrence estuary near the mouth of the Saguenay fjord using a network of 33 stations at slack low tide and 23 stations at slack high tide. The results show that, at low tide, Saguenay water forms a plume which extends more than 10 km from the mouth of the fjord into the estuary. At high tide the plume is restricted to the surface layer as the Saguenay waters are pushed back into the fjord.

Étude de la remontée relative des niveaux d'eau de l'estuaire du Saint-Laurent

1992 ◽  
Vol 19 (2) ◽  
pp. 252-259 ◽  
Author(s):  
François Anctil ◽  
Jean-Pierre Troude
Keyword(s):  
High Water ◽  
Water Levels ◽  
Freshwater Input ◽  
Relative Variation ◽  
Lawrence Estuary ◽  
High Discharge ◽  
Mean Water Level ◽  
Stability Of Water ◽  
St Lawrence Estuary ◽  
St Lawrence River

Data available on water levels in the St. Lawrence Estuary were used to evaluate the relative variation of mean water levels in this area. Only measurements taken at Pointe-au-Père could be used to evaluate this parameter with the required precision; a relative stability of water levels (−0.3 ± 0.5 mm/year) was observed. Upstream stations, especially the ones in the estuary, are highly influenced by the freshwater input of the St. Lawrence River. The high discharge of the river has been identified as the main cause of high water levels observed between 1970 and 1988 and, consequently, of bank erosion at the limit of the St. Lawrence estuary. Key words: discharge, erosion, estuary, mean water level, relative variation.

Distribution, Transport, and Composition of Suspended Matter in the St. Lawrence Estuary

1973 ◽  
Vol 10 (9) ◽  
pp. 1380-1396 ◽  
Author(s):  
Bruno F. d'Anglejan ◽  
Eric C. Smith
Keyword(s):  
Suspended Matter ◽  
Large Time ◽  
Total Suspended Matter ◽  
Quebec City ◽  
Lawrence Estuary ◽  
Tidal Circulation ◽  
Saguenay River ◽  
St Lawrence Estuary ◽  
Vertical Gradients ◽  
St Lawrence River

The distribution of total suspended matter in the estuary of the St. Lawrence River was studied by quantitative filtration through membrane filters. Tidal fluctuations in the vertical gradients of suspensoids were followed at fixed stations along the estuary. The concentrations varied from nearly 40 mg/1 below near Ile d'Orléans, to values less than 1 mg/1 at the downstream end of the upper estuary near the Saguenay River entrance. The tidal mean concentrations for the fixed stations ranged from 20 mg/1 to 2 mg/1. A turbidity maximum, which develops because of entrapments of particles by the tidal circulation, extends for 100 km below Quebec City. In this zone large vertical gradients changing in intensity with the tide by resuspension of settled material exist above the bottom. The total suspended matter is 60% to more than 90% inorganic by weight, and has a mean particle size between 5 and 7 μ. The annual rate of transport of suspended material out of the upper estuary at a section near the Saguenay River is estimated at less than 1 × 106 metric tons.Chemical and mineralogical analyses were performed on 23 suspensoid samples collected by centrifuging large volumes of water. The clay mineral composition of the less than 2 μ fraction is on the average 1.5% montmorillonite, 8% kaolinite, 31% chlorite, and 60% illite. However, large time and space variations are found both in the chemistry and mineralogy of the suspended matter.

scholarly journals Tumors in St. Lawrence Beluga Whales (Delphinapterus leucas)

1994 ◽  
Vol 31 (4) ◽  
pp. 444-449 ◽  
Author(s):  
S. De Guise ◽  
A. Lagacé ◽  
P. Béland
Keyword(s):  
Small Population ◽  
Delphinapterus Leucas ◽  
Carcinogenic Effect ◽  
Lawrence Estuary ◽  
Beluga Whales ◽  
High Prevalence ◽  
Endangered Population ◽  
High Concentrations ◽  
St Lawrence Estuary ◽  
St Lawrence River

A population of 450–500 belugas ( Delphinapterus leucas) resides in the polluted estuary of the St. Lawrence River. Stranded carcasses of this endangered population were recovered and necropsied. High concentrations of organochlorines, heavy metals, and benzo-a-pyrene exposure were demonstrated in tissues of these whales. Between 1988 and 1990, 21 tumors were found in 12 out of 24 carcasses. Among these tumors, six were malignant and 15 were benign. The animals were between 1.5 and >29 years of age, and the ages of animals with and without tumors did not differ when two juvenile animals (1.5 and 3.5 years of age) were excluded. Seven other neoplasms had been reported previously in six out of 21 well-preserved carcasses examined in the same laboratory between 1982 and 1987. Overall, 28 of the 75 confirmed tumors reported so far in cetaceans (37%) were from this small population of beluga whales in the St. Lawrence Estuary. Such a high prevalence of tumors would suggest an influence of contaminants through a direct carcinogenic effect and/or a decreased resistance to the development of tumors in this population.

The Limnological Units of the Lower Great Lakes - St. Lawrence River Corridor and Their Role in the Source and Aquatic Fate of Toxic Contaminants

1986 ◽  
Vol 21 (2) ◽  
pp. 168-186 ◽  
Author(s):  
R.J. Allan
Keyword(s):  
Great Lakes ◽  
Residence Time ◽  
Control Strategies ◽  
Salt Water ◽  
Transport Systems ◽  
Long Term Effects ◽  
Lawrence Estuary ◽  
St Lawrence Estuary ◽  
St Lawrence River

Abstract The waterways of the lower Great Lakes and St. Lawrence River, between Sarnia and the Saguenay Fiord, are made up of four limnological units. The first comprises the high discharge, rapid flow rivers, namely the St. Clair, Detroit, Niagara and St. Lawrence. Second are the four shallow, short residence time, riverine lakes, namely St. Clair, St. Francois, St. Louis and St. Pierre. Third are the two, relatively deep, long residence time, lower Great Lakes Erie and Ontario. Lastly, there is the freshwater-salt water mixing zone of the upper St. Lawrence Estuary. The rivers are essentially sources and transport systems of toxic contaminants on a grand scale. The riverine lakes provide only temporary storage or sinks even for contaminants associated with sediments because these are eventually resuspended and moved on downstream. The major sinks, where long-term effects are most evident are the two lower Great Lakes and the St. Lawrence Estuary. These sites are also where sediment associated contaminants can be permanently removed by deep burial in bottom sediments. However, even here, a proportion of the contaminant load passes on downstream and eventually out to the Gulf of St. Lawrence. The distinctive characteristics of the four limnological units are discussed in relation to sources and fate of toxic contaminants. Understanding the role of the units is critical to development of toxic chemicals control strategies and reduction in aquatic ecosystem contamination.

The Saguenay Fjord: A Third Factor in the Toxic Chemical Contamination of the St. Lawrence River Estuary

1990 ◽  
Vol 25 (1) ◽  
pp. 1-14
Author(s):  
R.J. Allan
Keyword(s):  
Toxic Metals ◽  
River Estuary ◽  
Organic Chemical ◽  
Organic Chemicals ◽  
Chemical Contamination ◽  
Lawrence Estuary ◽  
The Past ◽  
Saguenay Fjord ◽  
St Lawrence Estuary ◽  
St Lawrence River

Abstract The Saguenay Fjord enters the north shore of the St. Lawrence River estuary. The St. Lawrence River is one source of a variety of toxic metals and organic chemicals to its estuary. Some of these chemicals are transported by the river from its source in Lake Ontario and others are added along its course. However, the second major source of water inflow to the St. Lawrence Estuary is the Saguenay Fjord, which is by no means free of contamination. This paper overviews the types of toxic metals and organic chemical contamination and sources in the fjord proper and upstream in its drainage basin. The principal contaminants recorded in bottom sediments are polyaromatic hydrocarbons and mercury. An extensive forest products industry may also be a source of toxic chlorinated organic chemicals. The combined (peak) inputs of these chemicals to the Saguenay Fjord system was in the past and may have continued for many years, even decades. The relationship between the type of contaminants introduced in the past to the St. Lawrence estuary by the St. Lawrence River and the Saguenay Fjord may have implications concerning contamination of the beluga whale population which is located most frequently in the estuary near the fjord inflow.

Submarine Sand Dunes in the St. Lawrence Estuary

1971 ◽  
Vol 8 (11) ◽  
pp. 1480-1486 ◽  
Author(s):  
B. F. d'Anglejan
Keyword(s):  
Water Waves ◽  
Seismic Reflection ◽  
Sand Dunes ◽  
Wave Length ◽  
Quebec City ◽  
Lawrence Estuary ◽  
Seismic Reflection Profiling ◽  
St Lawrence Estuary ◽  
High Degree ◽  
St Lawrence River

Areas of sand dunes and ripples have been observed in the estuary of the St. Lawrence River below Quebec City. A train of dunes 18 km long is present in the channel of Ile-aux-Coudres. Symmetrical dunes as high as 12 m and reaching 120 m in wave-length are abundant. Symmetrical subsurface crests are also revealed by seismic reflection profiling. The mode of origin of these dunes is not yet established. However, because of the high degree of stratification present in the water column, the possible role played by internal water waves in their formation should be considered.

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