| St. Lawrence River Estuary Estuaire du Saint-Laurent (in French) | |
|---|---|
.JPG) Maritime section atPort-au-Saumon | |
   | |
| Etymology | Saint Lawrence of Rome |
| Location | |
| Country | Canada |
| Province | Quebec |
| Physical characteristics | |
| Source | Saint Lawrence River |
| • location | Lake Saint-Pierre,Trois-Rivières |
| • coordinates | 46°16′17″N72°38′5″W / 46.27139°N 72.63472°W /46.27139; -72.63472 |
| Mouth | Gulf of St. Lawrence /Atlantic Ocean |
• location | Pointe des Monts |
• coordinates | 49°19′N67°23′W / 49.317°N 67.383°W /49.317; -67.383 |
• elevation | 0 m (0 ft) |
| Discharge | |
| • location | below theSaint Lawrence River |
TheSt. Lawrence River Estuary is anestuary at the mouth of theSt. Lawrence River. It stretches 655 km from west to east, from the outlet ofLake Saint Pierre to Pointe-des-Monts,[1] where it becomes theGulf of St. Lawrence, inQuebec,Canada.
The estuary is divided into 3 parts: thefluvial estuary, themiddle estuary and themaritime estuary.[1][2] The waters coming from the north shore of the St. Lawrence andLabrador come mainly from theCanadian Shield.[3]
Among the deepest and largest estuaries in the world, the St. Lawrence maritime estuary extends nearly 250 km before it widens atPointe-des-Monts into the Gulf of St. Lawrence. This enclosed sea is connected to the Atlantic Ocean by Cabot Strait and the Strait of Belle-Isle.
The culture of theFirst Nations in Canada was largely based on birch, and theBirch bark canoe provided these hunting peoples with the mobility essential to this way of life.[5][6]
After crossing the Gulf of St. Lawrence, the itinerary of the first Europeans:whalers,fishermen, explorers andnavigators enters the waters of the Estuary, where the most difficult manoeuvres of the voyage begin: reefs, shoals, diagonal currents, fog and the presence of shallow channels, often narrow and winding, not to mention winter and ice and its unpredictable and fearsome storms. Throughout its history, the estuary of St. Lawrence River is not easily domesticated.[7]
FromLes Escoumins[8] to theGreat Lakes, St. Lawrencemaritime pilots experts in navigating specific sectors of the River[9] ensure the safe efficient passage of the vessels under their care.
Running for about 160 km, the fluvial estuary or estuarine section of the river extends from the outlet oflake Saint-Pierre[10][11] to theRCM L'Islet; the portion of the river under the power of freshwater tides.
The average depth of the main channel varies from 13 to 40 m, with pools of 21 m inTrois-Rivières-Ouest and 60 m inQuebec City.[2]
Starting with lake Saint-Pierre, the ecological conditions of the St. Lawrence underwent a radical change. The slow and continuous advance of the great mass of fresh water gradually gives way to the regime of the upflow tide, where twice every twenty-four hours the shores undergo a short alternation of emersion and immersion.[12]
The waters of the streams and rivers that flow into the river differ from those of the St. Lawrence in terms of temperature, chemical composition and suspended solids. The main rivers of the fluvial estuary, on the south shore, are theBécancour,Chaudière,Rivière du Sud rivers, on the north shore:St. MauriceChamplain,Batiscan,Sainte-Anne,Jacques-Cartier,Saint-Charles,Montmorency rivers and several secondary watercourses.
The waters retain their distinctiveness over a relatively long course before mixing. Those in theRivière des Outaouais keep their properties up to 25 km downstream from the mouth of the Saint-Maurice. Downstream ofGrondines, the currents of the rising tide (flood) reverse the direction of the river's flow. The result is an increasingly homogeneous stirring and mixing of fresh water from different sources.[2]
Extending along seven kilometres of shoreline in the St. Lawrence River's fluvial estuary, the Grondines and Sainte-Anne-de-la-Pérade swamp is one of the last, large, treed swamps on the river.[13][14]
BetweenSaint-Augustin-de-Desmaures andÎle aux Grues, from 2008 to 2012, three plants characteristic of the St. Lawrence freshwater estuary and in a precarious situation were monitored annually: Victorin's gentian (Gentianopsis virgata ssp. victorinii), Victorin's water-hemlock (Cicuta maculata var. victorinii) and Parker's Buckwheat (Eriocaulon parkeri).[15]
Running for about 195 km, the middle estuary of the St. Lawrence extends, according to the authors, from the eastern tip ofÎle d'Orléans[17] orSaint-Jean-Port-Joli, to the mouth of theSaguenay River. This estuary section widens rapidly from a few kilometres to 10 km, then to 20 km upstream ofÎle aux Coudres and the archipelago ofL'Isle-aux-Grues.[2]
The middle estuary is mainly characterized by the mixing of freshwater-influenced waters with salt water and highturbidity (turbid water). Thehydrodynamic conditions, mainly the reversal of tidal currents and the increase in thesalinity gradient, are such that a large amount of suspended solids is trapped and forms a muddy plug (turbidity zone). At ebb tide, the average water flow reaches 90,000 m3/s (fresh and salt water) inMontmagny.[2]
Over the millennia, severalgeomorphological events have shaped the landscape of the territory on the south shore of the middle estuary.
Thetectonic movements responsible for the genesis of theAppalachian Mountains explain the nature and configuration of thebedrock. Ice and interglacial periods led toglaciations, melts, and marine invasions, ice movements level the Appalachian Mountains. The large layers of sediment in the territory are the legacy of tectonic movements combined whit glacial and interglacial periods.[18]
Among the deepest and largest estuaries in the world, running for about 300 km, the maritime Estuary of the St. Lawrence extends from the mouth ofSaguenay River atTadoussac to Pointe-des-Monts where theGulf begins.
Along the shore, the Whale Route[19](Route 138), stretches from Tadoussac toLabrador. This national road is one of the best places in the world to observe marine mammals.[according to whom?] There, the two bodies of water that mix off the coast of Tadoussac give the Maritime Estuary characteristics that distinguish it from other reaches of the St. Lawrence: nutrient-rich surface waters throughout the summer and upwellings of deep, cold water that favour the formation ofkrill (euphausiids). Those organisms rise towards the surface near the shore, providing vast food stores for whales as largeBaleen whales,[20] as many others variety of whales and seals. It is home to the southernmostBeluga whale population in the world.[21][22]
This section is connected to theGulf of St. Lawrence, an enclosed sea leading to theAtlantic Ocean byCabot Strait and theStrait of Belle-Isle.[23]
The zone of contact between fresh and salt water corresponds to a region of high concentrations of suspended matter causing a zone of maximum turbidity (MTZ) of a length that can vary from 70 to 120 kilometres (43 to 75 mi), depending on the flow of the river.[24] This zone of maximum turbidity is located between Île d'Orléans (salinity greater than 0PSU) and Île aux Coudres (salinity below 10 PSU). The mechanisms of estuarine circulation associated with this environment make it a privileged site of primary and secondary production which shelters many fish nurseries. High environmental turbidity provides shelter against predators while larvae are maintained under optimum temperature and salinity conditions.[25][26][27] Large variations in salinity and turbidity result in a wide variety of physicochemical conditions and planktonic communities on the river.
An emblematic species is the beluga (beluga whale), but many other species are present. An identification guide for marine fishes of the estuary and northernGulf of St. Lawrence was completed in 2008.[28]
The coastline of Pointe des Monts on the North Shore and the city of Matane, opposite, in the Gaspé Peninsula, are the points that serve as the boundary between the estuary of the St. Lawrence River upstream, and the much wider Gulf of St. Lawrence, downstream.
The width of the Lower Estuary varies from 24 km to Tadoussac 50 km to Pointe-des-Monts
The one million square kilometre region includes the Canadian portion of the watersheds of rivers that flow into the St. Lawrence River from east of Montreal, into the Gulf of St. Lawrence and into the Atlantic Ocean.
Our team is composed of members from the Pekuakamiulnuatsh First Nation
Betula papyrifera Marshall. — Bouleau à papier. — Bouleau blanc, Bouleau à canot. — (Canoë birch).
In Canada, the most popular bark for canoe construction has come from the paper birch
The river, which the Amerindians had called "the walking way," was the only communication and transportation route for the pioneers.
The pilot station of the Corporation des pilotes du Bas-Saint-Laurent occupies the northern part of the cove, a 61-metre-long wharf that allows boarding the pilot boat.
Interest in working at sea, Excellent spatial perception, Ability to work in crisis situations and under unforeseen circumstances,
The effect of the tides is faintly perceptible in Lake Saint-Pierre, the last freshwater basin before the estuary
The estuarine section is the portion of the river under the power of freshwater tides
The diversity and number of birds that frequent the area's agricultural, forest and coastal lands are impressive — more than 100 bird species have been recorded in the area.
Regional landscape units The regional landscape unit is a territory of the order of a thousand square kilometers relatively homogeneous with regard to relief, altitude, geomorphology, hydrography and vegetation
Monitoring was carried out between Saint-Augustin-de-Desmaures and Île aux Grues, at 10 sites where at least one of these taxa was present.
The immense Saint Lawrence estuary emerges on the second part of the course, a veritable anti-chamber prior to the open ocean and the Atlantic.
Île d'Orléans is located in the upper estuary of the St. Lawrence River, three miles downstream from the city of Quebec
Study several geomorphological events have shaped the landscape of the territory
Whale-watching sites for everyone
The estuary is home to belugas all year round. In summer, the estuary also hosts rorquals and other species of toothed whales that benefit from the abundance of krill, capelin and other small fish.
The beluga whale frequents different habitats depending on the season and progression of ice breakup and freeze.
The abundance of food in the Marine Park's ecosystems attracts many species of birds, whales and seals.
Among the deepest and largest estuaries in the world
Important source of information on the status of marine resources harvested in the estuary and northern Gulf of St. Lawrence.
The expert training, precise knowledge and practical experience required of pilots are therefore indispensable for navigating this river.
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