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Ecoregion Description


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Species Richness


# of Endemic Species


Threats

118: Northeast US & Southeast Canada Atlantic Drainages

Major Habitat Type:

temperate coastal rivers

Author:

 Mary Burridge and Nicholas Mandrak

Countries:

Canada; United States

Boundaries:

This ecoregion stretches from Delaware in the United States to the Gaspé Peninsula of Quebec and New Brunswick in Canada.

Drainages flowing into:

The drainages flow into the Atlantic Ocean via the Gulf of St. Lawrence and the Bay of Fundy.

Main rivers or other water bodies:

The St. John River (673 km) is the second longest river in North America east of the Mississippi River and south of the St. Lawrence River. It originates in Maine and flows into the Bay of Fundy. Its tributaries include the Aroostook, Tobique, Kennebecasis and Jemseg rivers. The Miramichi River (250 km) flows into the Gulf of St. Lawrence and has a highly productive estuary. Its major tributaries include the northwest and southwest Miramichi rivers. The Restigouche River (200 km)winds through dense forests and rough terrain. Its major tributaries include the Kedgwick, Gounamitz, Patapedia and Upsalquitch rivers. The St. Croix River (185 km) has its headwaters in the Chiputneticook Lakes and flows southeast into the Bay of Fundy. It forms a natural border between New Brunswick and the state of Maine. The ecoregion also has several small lakes, the largest being Grand Lake, which is part of the St. John River watershed.

Topography:

This ecoregion lies within the ancient, eroded Appalachian Mountains. Glaciers shaped these mountains, forming plateaus, granite outcrops, and river valleys. In the Gaspé Peninsula peaks reach above 1000 m, whereas the New Brunswick Highlands range from 200-500 m above sea level. To the east are lowlands of sandstone and shale, with small bedrock outcrops forming hills. Southern New Brunswick is characterized by rolling terrain with stony till plains.

Climate:

This summer experiences a humid continental climate with warm summers (Köppen 1936). Total annual precipitation in New Brunswick ranges between 950 mm and 1150 mm.

Freshwater habitats:

The St. John River originates in the forests of Maine and slowly loops into New Brunswick where it flows through the St. John River valley. It drains into the Bay of Fundy where strong tides push back the river and create the famous Reversing Falls. The St. Croix River and the Upper Restigouche River are classified as Canadian Heritage Rivers. The St. Croix River consists of a widespread system of lakes around its headwaters, and extensive wetlands downstream. The Restigouche River is a gently meandering river with floodplains, terraces, islands, rock outcrops, and deep pools.

Terrestrial Habitats:

This ecoregion is a good example of temperate broadleaf and mixed forests, and is a transition zone between boreal spruce-fir forest to the north and deciduous forest to the south. The Atlantic Ocean strongly influences vegetation, especially in coastal areas. Tundra meadows occur on a few mountain peaks in the Christmas Mountains in New Brunswick. Low mountain slopes support a mixed forest of red spruce (Picea rubens), white spruce (P. glauca), balsam fir (Abies balsamea), red pine (Pinus resinosa), sugar maple (Acer saccharum), American beech (Fagus grandifolia), and yellow birch (Betula allegheniensis). Eastern hemlock (Tsuga canadensis) and eastern white pine (P. strobus) are also present. Along the east coast within the Gulf of St. Lawrence Lowland Forests terrestrial ecoregion, warm summers give rise to hardwood forests of sugar maple, yellow birch, and American beech. Eastern hemlock, balsam fir, and white pine (P. strobus) are also common in the lowlands. 

Fish Fauna:

The fish fauna of this ecoregion is largely comprised of species originating in the Atlantic Coastal refugium, which was less speciose than the Mississippian refugium. As a result, the fauna is depauparate relative to the faunas of central Canada, although it is moderately rich compared to other temperate coastal river ecoregions. It is dominated by secondary freshwater fishes such as sturgeons (Acipenser spp.), shads (Alosa spp.), smelts (Osmeridae), American eel (Anguilla rostrata), sticklebacks (Gasterosteidae), killifishes (Fundulus spp.), and temperate basses (Morone spp.).

Description of endemic fishes:

An endemic dwarf smelt (Osmerus spp.) in Lake Utopia, New Brunswick has been identified, but not formally described.

Other noteworthy fishes:

Some landlocked freshwater populations of the primarily marine tomcod (Microgadus tomcod) are found in this ecoregion.

Ecological phenomena:

Many species in this ecoregion exhibit diadromy including lampreys (Lampetra spp.), sturgeons (Acipenser spp.), shads (Alosa spp.), smelts (Osmeridae), American eel (Anguilla rostrata), Atlantic salmon (Salmo salar), and temperate basses (Morone spp.).

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 extent of the Northeast US and Southeast Canada Atlantic Drainages ecoregion was determined by including fish occurrence data for watersheds in contiguous watersheds of the northeast United States. The North Atlantic Ecoregion is comprised of watersheds that flow into Gulf of St. Lawrence and the Bay of Fundy in Canada, and directly into the Atlantic Ocean in the United States. The fish fauna of this ecoregion is largely comprised of species originating in the Atlantic Coastal refugium, which was less speciose than the Mississippian refugium. As a result, the fauna is depauparate relative to the faunas of central Canada, and is dominated by saltwater-tolerant freshwater fishes.

Level of taxonomic exploration:

Fair

References/sources:

Abell, R., Olson, D., et al. (2000). "Freshwater ecoregions of North America" Washington, D.C.: Island Press.

Eswg (1995) "A national ecological framework for Canada". Ottawa/Hull, Ontario, Canada. Agriculture and Agri-food Canada, Research Branch, Centre for Land and Biological Resources Research; and Environment Canada, State of the Environment Directorate, Ecozone Analysis Branch..

Ricketts, Taylor H. Dinerstein Eric Olson David M. Loucks Colby J. (1999). "Terrestrial ecoregions of North America: A conservation assessment" Washington, D.C.: World Wildlife Fund.

Scott, W. B.,Crossman, E. J. (1998). "Freshwater fishes of Canada" Fisheries Research Board of Canada Bulletin 184 966 + xvii..

The Nature Conservancy World Wildlife Fund
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