6
Study Area
CABO
OESEAOO
N
*
PATAGONIA
TIERRA DEL FUEGO
PUNTA
OUGENESS
52" 45' S
~
~ ~ ('I
'b
~
54' 45' S
7S' 30' W
73" 30'W
71 ' 30'W
69" 30'W
67' 30' ~
Fig. 1.6. Mean values of tidal amplitude (m) in the Straits of Magellan. (After Medeiros and Kjerfve 1988)
tide ranges are 1.2 and 1.8 m for the Segunda
Angostura,
Tidal currents can reach velocities greater
than 4.5 m/s in narrow passages such as the
Primera Angostura and 3 m/s in the Segunda
Angostura. Lower speeds are recorded at the
Atlantic entrance (2.5 m/s) and in the Ancho
Canal (1.9 m/s). At the Atlantic opening at a
depth of 40 m, speeds of 80-100 em Is have
been measured in an east-west direction
(Michelato et al. 1991). At the same time,
bottom speeds are less than half these values
due to friction. Maximum speeds of up to
1.25-1.30m/s have been recorded at the 1020m depth between the two Angosturas. On
the Pacific side of the Straits, the tidal regime
is mixed, mainly semidiurnal, with speeds of
1.1-1.2 m/s.
1.4 Chemical Characteristics
The western part of the Straits, which is
deeper and narrower, differs from the eastern
sector due to the strong vertical gradient of
chemical properties at a depth of about 100 m
as reported by Catalano and Goffart (1991)
for the austral summer 1991. The water
column in this region differs with respect to
the rest of the Straits in the generally smaller
content of oxygen (Fig. 1.7) and the greater
presence of nitrite plus nitrate (Fig. 1.8). The
Straits therefore appear to be sub-divided by
the sill of Carlos III Island into at least two
large zones, each one of which is further
divided into smaller zones owing to particular
local phenomena that seem to be mainly
related to the morphology of the area.
1.5 Photosynthetic Pigments and
Primary Production
Phytoplankton pigment distributions along
the entire channel are given by Panella et al.
(1991a) for the austral spring 1989 when low
levels «1 J.lg/I) of total ChI a were observed
in the Pacific area. The richest area, in terms
Study Area
CABO
OESEAOO
N
*
PATAGONIA
TIERRA DEL FUEGO
PUNTA
OUGENESS
52" 45' S
~
~ ~ ('I
'b
~
54' 45' S
7S' 30' W
73" 30'W
71 ' 30'W
69" 30'W
67' 30' ~
Fig. 1.6. Mean values of tidal amplitude (m) in the Straits of Magellan. (After Medeiros and Kjerfve 1988)
tide ranges are 1.2 and 1.8 m for the Segunda
Angostura,
Tidal currents can reach velocities greater
than 4.5 m/s in narrow passages such as the
Primera Angostura and 3 m/s in the Segunda
Angostura. Lower speeds are recorded at the
Atlantic entrance (2.5 m/s) and in the Ancho
Canal (1.9 m/s). At the Atlantic opening at a
depth of 40 m, speeds of 80-100 em Is have
been measured in an east-west direction
(Michelato et al. 1991). At the same time,
bottom speeds are less than half these values
due to friction. Maximum speeds of up to
1.25-1.30m/s have been recorded at the 1020m depth between the two Angosturas. On
the Pacific side of the Straits, the tidal regime
is mixed, mainly semidiurnal, with speeds of
1.1-1.2 m/s.
1.4 Chemical Characteristics
The western part of the Straits, which is
deeper and narrower, differs from the eastern
sector due to the strong vertical gradient of
chemical properties at a depth of about 100 m
as reported by Catalano and Goffart (1991)
for the austral summer 1991. The water
column in this region differs with respect to
the rest of the Straits in the generally smaller
content of oxygen (Fig. 1.7) and the greater
presence of nitrite plus nitrate (Fig. 1.8). The
Straits therefore appear to be sub-divided by
the sill of Carlos III Island into at least two
large zones, each one of which is further
divided into smaller zones owing to particular
local phenomena that seem to be mainly
related to the morphology of the area.
1.5 Photosynthetic Pigments and
Primary Production
Phytoplankton pigment distributions along
the entire channel are given by Panella et al.
(1991a) for the austral spring 1989 when low
levels «1 J.lg/I) of total ChI a were observed
in the Pacific area. The richest area, in terms