Geoscience Reference
In-Depth Information
day tragedy of the collapse of the northern cod stocks from overfishing, these waters continue to feed a United
Nations of seabirds—some 5 million pairs that breed on the islands and cliffs of Newfoundland and Labrador,
and 35 to 45 million more that congregate offshore during the nonbreeding season.
Coastal and Offshore Habitats
Within each of these far-flung regions, the major marine habitats occur with varying frequencies and with vari-
ations in the native flora and fauna, depending upon the local environmental conditions. Estuaries, large and
small, are found all along the coastline wherever a river drains into the sea. By definition, an estuary is a place
where fresh and salt waters meet and mix. The term derives from the Latin aestuare—“to heave, boil, surge, be
in commotion.” Most estuaries are highly productive. The turbulent clash of fresh and salt waters underpins
this productivity by keeping nutrients in suspension and available to the host of plants and animals that make
up the estuarine food web. Two of the major estuaries along the entire Atlantic coast are Chesapeake and
Delaware Bays, which receive the outflow of rivers draining from the Piedmont Plateau, east of the Appalachi-
ans, toward the Atlantic Coastal Plain. The whole of the Gulf of St. Lawrence, which collects a massive input
of freshwater from the Great Lakes, has been described as a large estuary.
The autumnal gold of a salt marsh will soon bequeath its biological riches to the adjacent marine zone.
The most productive of the marine habitats is the salt marsh. In fact, salt marshes are among the richest hab-
itats on land or sea; their primary production, acre for acre, often exceeds the output of agricultural crops such
as wheat and corn. Salt marshes are formed where the tide floods over the land, usually twice a day in accord-
