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ST. LAWRENCE INFO
Upper Estuary and Saguenay River
The upper estuary covers an area 150 km long from the eastern tip of Ile d’Orléans to the mouth of the Saguenay River (SLC, 1996a). The average width of this section of the river is 17 km while its depth varies from 100 to 300 m. Fifty-odd islands and islets, including Ile aux Grues, Ile aux Coudres and Ile Verte, are found in this river stretch.
The upper estuary is characterized by the mixing of fresh and salt water, driven by a combination of high-intensity currents and the influence of the tide. The resuspended sediment makes for highly turbid water, which is especially pronounced in the area between Ile d’Orléans and Ile aux Coudres. The location of this maximum turbidity zone (MTZ) shifts according to the tide and the flow of fresh water.
The saltwater transition zone limits the development of both freshwater and saltwater plant and animal species. The diversity of plant communities on tidal flats diminishes as salinity increases; American Bulrush communities are the most common. Birds, on the other hand, are very abundant. Individuals of single species, including the Greater Snow Goose, are found in enormous numbers, but overall species diversity diminishes.
Back to the Hydrographic Divisions of the St. Lawrence River |
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