Greenland Current and the Labrador Current, the
polar pack ice is carried far to the south end of the
Grand Banks (46
N). In contrast, the extension
of the warm Gulf Stream system keeps ice-free
during the entire year, the eastern side of the
Norwegian Sea and the southern Barents Sea.
This allowed convoys from America during
World War II to reach the Russian (formerly
Soviet) port of Murmansk.
In summer the hydrologic conditions of the Ba¨
regions do not differ considerably from those of
the Wp regions. This is especially true for the
Southern Hemisphere where variable, predominantly easterly currents are common to both
regions. The boundaries between the two
regions, as well as the boundary between the
two polar regions, favor the development plankton. In the feeding chain, plankton forms the
basis of krill shrimp on which, the blue whales
and finback whales feed. These relationships
explain why, in summer, the two boundaries
become the main feeding grounds of the whales,
and consequently the main whaling grounds.
3.2
600 Temperate Domain
This comprises the middle latitudes between the
poleward limits of the tropics and the equatorward limits of pack ice in winter. Currents in this
region correspond to wind movements around
the subtropical, high-pressure cells of the atmosphere. These are the so-called mixed waters of
the middle latitudes. The variable direction of the
current determines the divisions: (a) a poleward
westerlies zone (division) with cold water and
sea ice that is poleward of the oceanic polar
front; (b) an equatorward westerlies zone (division) that has cool water and is equatorward of
the oceanic polar front; (c) a subtropical zone
(division) with weak currents of variable
directions; (d) a high-salinity, subtropical zone
Fig. 3.1 Divisions of the oceanic polar domain
18
3 Ecoregions of the Oceans
polar pack ice is carried far to the south end of the
Grand Banks (46
N). In contrast, the extension
of the warm Gulf Stream system keeps ice-free
during the entire year, the eastern side of the
Norwegian Sea and the southern Barents Sea.
This allowed convoys from America during
World War II to reach the Russian (formerly
Soviet) port of Murmansk.
In summer the hydrologic conditions of the Ba¨
regions do not differ considerably from those of
the Wp regions. This is especially true for the
Southern Hemisphere where variable, predominantly easterly currents are common to both
regions. The boundaries between the two
regions, as well as the boundary between the
two polar regions, favor the development plankton. In the feeding chain, plankton forms the
basis of krill shrimp on which, the blue whales
and finback whales feed. These relationships
explain why, in summer, the two boundaries
become the main feeding grounds of the whales,
and consequently the main whaling grounds.
3.2
600 Temperate Domain
This comprises the middle latitudes between the
poleward limits of the tropics and the equatorward limits of pack ice in winter. Currents in this
region correspond to wind movements around
the subtropical, high-pressure cells of the atmosphere. These are the so-called mixed waters of
the middle latitudes. The variable direction of the
current determines the divisions: (a) a poleward
westerlies zone (division) with cold water and
sea ice that is poleward of the oceanic polar
front; (b) an equatorward westerlies zone (division) that has cool water and is equatorward of
the oceanic polar front; (c) a subtropical zone
(division) with weak currents of variable
directions; (d) a high-salinity, subtropical zone
Fig. 3.1 Divisions of the oceanic polar domain
18
3 Ecoregions of the Oceans