8
Study Area
Pacific
AUanUc -
10
20
30
:§:
4 0
,s
SC
a. eo
Q)
0
70
eo
90
100
.2
.3
Chi a
E
A
~
. ~
[>O.SlImJ
,s
.S
a. .7
Q)
0
•
.8
10
1. 1
, I I
.
J I
1.2
-so
0
50
100
150
200
250
300
3SO
400
450
500
550
Distance (Km)
Fig. 1.9. Distribution of total chlorophyll a along the main axis of the Straits of Magellan during the austral spring
1989. (After Panella et al. 1991a)
of total ChI a, was in the Central region, from
Carlos III Island to Paso Ancho. Maximum
values of total ChI a (>7/lg/l) occurred east
of Cape Froward (Fig_ 1.9). Along the axis of
the Straits, the highest percentage of ChI a
was found in the micro- and nanophytoplankton fractions (>2/lm). The picophytoplankton fraction «2 /lm) showed a similar
pattern to the other fractions but with much
lower concentrations «0.6 /lg/l) (Fig. 1.10).
During the austral summer 1991, the
richest area was that of Paso Ancho with
values in excess of 2 /lg/l (Fig. 1.11) (Saggiomo
et al. 1994). The microphytoplankton fraction was mainly confined to the Pacific
entrance and to the embayment between the
two Narrows while in the rest of the Straits
it was always less than 5% of the total
assemblage. The nano- and picoplankton
fractions occurred throughout the entire
lengths of the Straits, comprising a mean of
33 and 63% of the entire phytoplankton
assemblage, respectively. The integrated
values of ChI a during the same cruise are
given by Magazzu et al. (1991) (Fig. 1.12)
who also report values for primary production (Fig. 1.13). In the Andean area lowest
values of primary production were observed
(282 mg C/m2/d) in an extremely mil'ed water
column (Artegiani et al. 1991) with high
nutrient concentrations (Catalano and
Goffart 1991). By contrast, the highest values
of primary production (above 1000mgC/m2/
d) were observed in Paso Ancho and Bahia
Inutil, in a thermally stratified water column
characterized by low nutrient concentrations.
1.6 Particulate Organic Matter
In the austral summer 1991, the Straits were
characterized by low concentrations and
large variations in quali-quantitative composition of the seston. The surface values of
total suspended matter (TSM) ranged from
to 0.5 mg/dm 3 in Pacific waters to 2 mg/dm 3
in the area between the two Angosturas (Fig.
1.14). High surface TSM values occurred
near Paso Ancho with average values of
Study Area
Pacific
AUanUc -
10
20
30
:§:
4 0
,s
SC
a. eo
Q)
0
70
eo
90
100
.2
.3
Chi a
E
A
~
. ~
[>O.SlImJ
,s
.S
a. .7
Q)
0
•
.8
10
1. 1
, I I
.
J I
1.2
-so
0
50
100
150
200
250
300
3SO
400
450
500
550
Distance (Km)
Fig. 1.9. Distribution of total chlorophyll a along the main axis of the Straits of Magellan during the austral spring
1989. (After Panella et al. 1991a)
of total ChI a, was in the Central region, from
Carlos III Island to Paso Ancho. Maximum
values of total ChI a (>7/lg/l) occurred east
of Cape Froward (Fig_ 1.9). Along the axis of
the Straits, the highest percentage of ChI a
was found in the micro- and nanophytoplankton fractions (>2/lm). The picophytoplankton fraction «2 /lm) showed a similar
pattern to the other fractions but with much
lower concentrations «0.6 /lg/l) (Fig. 1.10).
During the austral summer 1991, the
richest area was that of Paso Ancho with
values in excess of 2 /lg/l (Fig. 1.11) (Saggiomo
et al. 1994). The microphytoplankton fraction was mainly confined to the Pacific
entrance and to the embayment between the
two Narrows while in the rest of the Straits
it was always less than 5% of the total
assemblage. The nano- and picoplankton
fractions occurred throughout the entire
lengths of the Straits, comprising a mean of
33 and 63% of the entire phytoplankton
assemblage, respectively. The integrated
values of ChI a during the same cruise are
given by Magazzu et al. (1991) (Fig. 1.12)
who also report values for primary production (Fig. 1.13). In the Andean area lowest
values of primary production were observed
(282 mg C/m2/d) in an extremely mil'ed water
column (Artegiani et al. 1991) with high
nutrient concentrations (Catalano and
Goffart 1991). By contrast, the highest values
of primary production (above 1000mgC/m2/
d) were observed in Paso Ancho and Bahia
Inutil, in a thermally stratified water column
characterized by low nutrient concentrations.
1.6 Particulate Organic Matter
In the austral summer 1991, the Straits were
characterized by low concentrations and
large variations in quali-quantitative composition of the seston. The surface values of
total suspended matter (TSM) ranged from
to 0.5 mg/dm 3 in Pacific waters to 2 mg/dm 3
in the area between the two Angosturas (Fig.
1.14). High surface TSM values occurred
near Paso Ancho with average values of