|
This eco-region comprises the sub-tropical Atlantic
costal waters of the US states of Georgia and Florida,
plus the islands of the Bahamas.
Sub-tropical continental Shelves and their seas are
generally moderately productive regions of great biological
significance, hosting resident and migratory fauna
during various stages of their life cycle.
The relatively shallow waters lead to warmer temperatures
and seasonal stratification of the water column based
on temperature. Seasonal variation, combined with
inflows of freshwater from coastal streams and tidal
action, contribute to a variety of habitats and a
high degree of biodiversity.
The continental shelf of the southeastern United
States is no exception to this general description.
It is a diverse and productive upwelling area, as
offshore currents drawing away warm surface water
create an upward flow of cold, heavy deep-sea water.
The deep-sea water of upwellings is generally rich
in nutrients. Upwellings of the sub-tropical waters
of the Southeast shelf ecosystem, however, are not
as intense and evident as in the higher latitude regions.
The major currents in the North Atlantic flow in
a clockwise direction. This huge area of rotating
water is better known as the North Atlantic Gyre (spiral).
If you were to drop a bottle in the Gulf Stream off
the Georgia coast, you would probably find it somewhere
off the Irish or English coasts within one year. It
could then find its way down the Atlantic coast of
southern Europe, then Africa, then head west just
north of the Equator and turn northwest until it washed
back up onto the beaches of the eastern United States.
It would take in the region of three years for the
bottle to complete its journey back to Georgia.
Bays and sounds with extensive coastal marshes are
characteristic of this eco-region. These wetlands
form unique habitats that provide important links
to production of living marine resources.
A 10 to 20 km-wide coastal zone is characterized
by high levels of plankton production throughout the
year, while offshore, on the middle and outer shelf,
upwelling along the Gulf Stream front and intrusions
from the Gulf Stream cause short-lived plankton blooms.
Both commercial and recreational fishing interests
target the principal fishery resources in the Southeast
region.
A broad array of wide-ranging and highly migratory
oceanic pelagic fish species is found here. These
highly migratory species include swordfish, bluefin
tuna, yellowfin tuna, bigeye tuna, albacore, skipjack
tuna, blue and white marlin, sailfish, and others.
Reef fishes include more than 100 species that prefer
coral reefs, artificial structures, or other hard-bottom
areas, and tilefishes that prefer muddy bottom areas.
They range along the coast to a depth of about 200
meters. These compete with other reef fauna, including
spiny lobsters, conch, stone crab and corals.
Coastal pelagic fishes inhabiting waters of the
eco-region include king mackerel, Spanish mackerel,
cobia, dolphin, and cero.
Municipal wastewater treatment plants and pesticides
applied to agricultural lands are the major sources
of coastal pollution.
|