116
Lisa A. LEVIN and Andrew J. GOODAY
Fig. 5.1. Locations of major sampling programs within the deep Atlantic. CVAP, Cape Verde Abyssal Plain; MAP, Madeira Abyssal Plain;
PSB, Porcupine Seabight; TAP, Tagus Abyssal Plain. The numbers identify national and international research projects listed in Table 5.1.
(1, Rockall Trough time series; 2, IOSDL Porcupine Seabight Programme; 3, OMEX; 4, BIOGAS; 5, EU MAST I; 6, EU MAST II; 7, EU
MAST III; 8, BIOTRANS and its successors; 9, DORA; 10, EUMELI).
the Rockall Trough, becoming progressively diluted
as it proceeds northwards. Mediterranean Water is
characterized by high density and salinity and by its
variable physical properties (Weston, 1985).
The deep bottom water in the South Atlantic lies
below the “conveyer belt” and is derived mainly from
the Weddell Sea (Mantyla and Reid, 1983; Mackensen
et al., 1995). The deep Weddell Sea Bottom Water
is too cold and dense to escape from the Antarctic.
The AABW which penetrates northwards into the
South Atlantic is lighter, and consists of a mixture
of three separate water masses, dominated (>50%)
by Circumpolar Water (CPW). The AABW flows
from the Weddell Sea into the Argentine and Brazil
Basins via the Scotia Sea and Georgia Basin, and
is characterized by low temperature and salinity and
relatively high concentrations of oxygen and nutrients.
From the Brazil Basin, it either escapes northwards into
the Guiana Basin, or circles eastwards and southwards,
via the Romanche Fracture Zone, into the southeastern
Atlantic basins.
Bottom-water oxygen concentrations in the Atlantic
are generally higher (>5 ml °
−1 ) than in the Pacific and
Indian Oceans, particularly in water of North Atlantic
origin (Mantyla and Reid, 1983; Reid, 1996, fig. 2
therein), and severe oxygen depletion (<0.2 ml °
−1 ) is
not as extensive as in marginal regions of these other
oceans (Diaz and Rosenberg, 1995, fig. 1 therein).
Areas of intermediate depth with bottom-water oxygen
depletion are associated with upwelling on the eastern
side of the Atlantic. The two main areas in the Atlantic
are off Northwest Africa, where upwelling is associated
with the Canary Current, and off Southwest Africa
where it is associated with the Benguela Current
Lisa A. LEVIN and Andrew J. GOODAY
Fig. 5.1. Locations of major sampling programs within the deep Atlantic. CVAP, Cape Verde Abyssal Plain; MAP, Madeira Abyssal Plain;
PSB, Porcupine Seabight; TAP, Tagus Abyssal Plain. The numbers identify national and international research projects listed in Table 5.1.
(1, Rockall Trough time series; 2, IOSDL Porcupine Seabight Programme; 3, OMEX; 4, BIOGAS; 5, EU MAST I; 6, EU MAST II; 7, EU
MAST III; 8, BIOTRANS and its successors; 9, DORA; 10, EUMELI).
the Rockall Trough, becoming progressively diluted
as it proceeds northwards. Mediterranean Water is
characterized by high density and salinity and by its
variable physical properties (Weston, 1985).
The deep bottom water in the South Atlantic lies
below the “conveyer belt” and is derived mainly from
the Weddell Sea (Mantyla and Reid, 1983; Mackensen
et al., 1995). The deep Weddell Sea Bottom Water
is too cold and dense to escape from the Antarctic.
The AABW which penetrates northwards into the
South Atlantic is lighter, and consists of a mixture
of three separate water masses, dominated (>50%)
by Circumpolar Water (CPW). The AABW flows
from the Weddell Sea into the Argentine and Brazil
Basins via the Scotia Sea and Georgia Basin, and
is characterized by low temperature and salinity and
relatively high concentrations of oxygen and nutrients.
From the Brazil Basin, it either escapes northwards into
the Guiana Basin, or circles eastwards and southwards,
via the Romanche Fracture Zone, into the southeastern
Atlantic basins.
Bottom-water oxygen concentrations in the Atlantic
are generally higher (>5 ml °
−1 ) than in the Pacific and
Indian Oceans, particularly in water of North Atlantic
origin (Mantyla and Reid, 1983; Reid, 1996, fig. 2
therein), and severe oxygen depletion (<0.2 ml °
−1 ) is
not as extensive as in marginal regions of these other
oceans (Diaz and Rosenberg, 1995, fig. 1 therein).
Areas of intermediate depth with bottom-water oxygen
depletion are associated with upwelling on the eastern
side of the Atlantic. The two main areas in the Atlantic
are off Northwest Africa, where upwelling is associated
with the Canary Current, and off Southwest Africa
where it is associated with the Benguela Current