Boundaries

This ecoregion is defined largely by the drainages along the north shore of the Gulf of St. Lawrence from the Saguenay River drainage east to the Atlantic Ocean. The ecoregion covers part of southern Quebec and southern mainland Newfoundland (Labrador).

Topography

The ecoregion is underlain by Precambrian and Archean granites and gneisses, with elevations ranging between sea level and 1000 m. Steep slopes occur along the coast, and wide river valleys incise the rolling and undulating terrain within the interior (Ricketts et al. 1999).

Freshwater habitats

The drainages are dominated by moderately large lakes and rivers carved out Canadian Shield by the last Ice Age. Unlike most of the freshwater habitats in eastern Canada that were formed as a result of glaciation, Lake Manicouagan in Quebec was formed by a different mechanism. A nearly circular ring around a central island, this lake is the crater of a huge bolide impact that occurred some 212 million years ago. The crater has been worn down by repeated glaciation (Strain and Engle 1993).

Terrestrial habitats

The ecoregion is characterized by boreal forest, dominated by a mix of balsam fir (Abies balsamea) and black spruce (Picea mariana). Balsam fir is more prevalent toward the eastern part of the ecoregion due to the maritime influence of the Atlantic, and white spruce (Picea glauca) dominates in coastal areas affected by sea salt spray. Moss-heath vegetation or barrens are also common in coastal areas affected by high winds (Ricketts et al. 1999).

Description of endemic fishes

There are no known endemic species in this ecoregion.

Other noteworthy fishes

The marine tomcod (Microgadus tomcod) has established a landlocked population in Lake St. John, Quebec.

Ecological phenomena

This ecoregion was noted for runs of catadromous American eel and anadromous Atlantic salmon; however, stocks of both these species are declining.

Justification for delineation

The ecoregions of Canada were identified based on the faunal similarity of 166 major watersheds based on a cluster analysis of freshwater fish occurrences in these watersheds. The Gulf of St. Lawrence ecoregion contains watersheds that drain into the Gulf of St. Lawrence, a marine barrier to the dispersal of freshwater fishes. Given its isolation and large distances from glacial refugia, the fish fauna of this ecoregion is relatively depauparate, but most characteristic of the fauna derived from the closest refugium – the Atlantic refugium.

Level of taxonomic exploration

Fair