Rock and landscapes

The marine park lies within two major geological formations. The area comprising the Saguenay Fjord and the north shore of the St. Lawrence is part of the Canadian Shield, a crystalline rock basement formed from 600 million to 4 billion years ago. The south shore of the St. Lawrence and the mid-estuary islands are part of the Appalachians, a mountain range composed of sedimentary rock hundreds of millions of years old. Between these two formations lie the St. Lawrence Lowlands, formed of more recent sedimentary rock.

The terrain and landscapes of the estuary and fjord have also been sculpted by a variety of geological processes: collapses due to movement of the Earth’s crust, the passage of glaciers and submersion beneath the ocean.

Currents and tides

The Saguenay-St. Lawrence Marine Park is located half-way between the Great Lakes and the Atlantic Ocean. Waters from the immense hydrographic basins of the St. Lawrence and Saguenay Rivers and from the Atlantic Ocean meet here with force, creating a dynamic and rich marine environment.

In the St. Lawrence Estuary, fresh waters flow on the surface seaward, whereas deep Atlantic waters flow slowly counter-current upstream. The salty waters from the Atlantic enter the St. Lawrence Gulf and the Estuary through the Laurentian Channel, a submarine canyon 1200 km long that leads to the Saguenay River mouth. There is the head of the Laurentian Channel, where the seafloor rises from 300 to 20 meters. Twice daily at rising tide, the cold salt water layer hits the channel head, forced up to the surface.

Upwelling

Sites of cold salt water rising to the surface, like the one found in the Marine Park, are commonly called upwelling. They are the most productive areas in the oceans. The upwelling carries nutrients and zooplankton towards the surface and oxygenates the waters. This phenomenon triggers a high production and concentration of food sought out by wide diversity of predators such as fish, seabirds and marine mammals. The upwelling represents in some ways the beating heart and the lungs of the Marine Park.

Plankton

Plankton designates the tiny plant and animal species that drift in the water, carried about by the currents.

Planktonic organisms that are part of the plant world are known as phytoplankton. In the estuary, they reach peak numbers between June and September. Those that are members of the animal world constitute zooplankton. These little organisms serve as food for many of the marine mammals frequenting park waters.

Fish

No fewer than 94 species of fish have been documented in the marine park. They use a wide variety of habitats. Most are typically saltwater or estuarine species, but about a dozen are typical of freshwater habitats. Of note, species such as the American Sand Lance, the Capelin, and the Atlantic Herring live in schools, and serve as readily accessible food for several marine mammals. Some whales literally “graze” these fields… of fish!

Seabirds

The marine park region is a paradise for ornithologists and birders! The waters of the estuary and fjord lie adjacent to a multitude of terrestrial habitats, over 150 bird species have been recorded here.

Some of these species are seabirds, whose diet consists largely of invertebrates and saltwater fish. In this group are shorebirds, or limicolous species (woodcocks, sandpipers, etc.); pelagic birds, such as the dovekie, that live on the water and feed there on plankton; and diving birds, such as the fish-eating gulls and cormorants, and the eider ducks and scoters that feed on molluscs and crustaceans.

These birds use the marine milieu for other purposes as well. It provides a place where they can rest, moult sheltered from predators, reproduce, and rear their young, overwinter. Many of the islands in the estuary hold seabird colonies.

Marine mammals

Nine species of marine mammals regularly frequent the waters of the park. The Beluga and the Harbour Seal live here year round.

Three of these species are pinnipeds: the Harbour Seal, Grey Seal and Harp Seal. The other six are cetaceans: the Beluga, Harbour Porpoise, Minke Whale, Fin Whale, Blue Whale and Humpback Whale.

Other marine mammals can occasionally be seen: sperm whales, white-sided dolphins, hood seals and right whales. There have even been rare sightings of the Long-finned Pilot Whale, White-beaked Dolphin and Killer Whale.

Organisms of the seabed

Many park plants and animals live on or near the seabed. These organisms inhabit three distinct zones, each with its own particular conditions.

The intertidal zone is located between the high- and low-tide marks, and is twice a day exposed to the open air. It is inhabited by marsh plants, algae, (Ascophyllum, Fucus), blue mussels, and periwinkles... each at a specific height.

The subtidal zone lies between the low-tide mark and a depth of 200 metres. Where the seabed is rocky, brown algae (Alaria and Laminaria), red algae, small crustaceans, blue mussels and starfish flourish next to such colourful organisms as anemones and sponges. In contrast, quahogs, Polychaeta sp. (sea worms), whelks and Ophiwia sp. (brittle stars) dominate where the substrate is soft.

The bathyal zone, a deeper underwater area, is inhabited primarily by Polychaeta sp.