NOT TO BE CITED WITHOUT PRIOR REFERENCE TO THE AUTHOR
ICES STATUTORY MEETING 1993
ICES CM 1993\ L:63
Session 0
SPATIAL VARIATION OF THE ZOOPLANKTON BIOMASS IN RELATION TO
THE HYDROGRAPHIC CONDITIONS OFF THE PORTUGUESE COAST
M. Emilia CUNHA
Instituto Naeional de Investiga9äo das Peseas, Av.Brasilia,
1400 Lisboa, Portugal
ABSTRACT
Spatial variation of the zooplankton biomass in relation
to the hydrographie eonditions off the Portuguese eoast is
analyzed based on data from surveys eovering the entire eoast
earried out in August 85, November 85, January 86 and
March/April 86 and from sampIes eolleeted monthly from
Oetober 86 through January 89 in two transepts over the
northern eontinental shelf.
The spatial distribution of zooplankton seemed to be
strongly related to the eireulation pattern of the upper
layers, to the topology of the eoast and eontinental shelf
and to the loeal wind foreing. In the southwest eoast, with
a very steep shelf and virtually no shelf break, zooplankton
was more abundant offshore during Winter and early Spring.
During this period the Subtropical eomponent of the Eastern
North Atlantie Central Water in i ts northward flow approaehed
the eoast and transported great amounts of zooplankton. In
the northern eoast and during Summer and late Autumn
zooplankton biomass was eoncentrated very near the eoast and
on a band over the mid-shelf. The flat and wide shelf in this
region seems to permit the establishment of a two eells
cross-stream eirculation with a offshore convergenee front
between the two cells during upwelling.
INTRODUCTION
The Portuguese coast, occupies together with the Galician
coast the northern limit of the upwelling areas associated with
the North Atlantic anticyc10nic gyre. The hydrography and pe1agic
ecology of this area are strongly seasonal and influenced by the
coastal morphology and shelf topography. Winter winds from the
southwest, which produce surface flow from the south and toward
the shore alternate with summer winds from the north, which
produce flow from the north and away from shore, generating
coastal upwelling (Fiuza, 1982). These seasonal changes in the
sources of currents flowing through the Portuguese coast and the
different upwel1ing patterns originated by differences in the
shelf topography may cause changes in phytoplankton and
zooplankton species and standing crops (Cunha, M. E. , Moita, M. T. ,
1991).
This paper describes the hydrography and circulation
patterns of the Portuguese coast and summarize the distributions
of the zooplankton biomass in relation to the hydrography.
PHYSICAL OCEANOGRAPHY OF THE PORTUGUESE COAST
The water masses present in the upper few hundred meters of
the water column over the Portuguese continental margin are two
components of the Eastern North Atlantic Central Water (ENACW):
the Subpolar component with a origin at the west of the Biscay
Bay and conforming the North Atlantic Central Water (NACW) as
defined by Sverdrup et al. (1942) and the Subtropical component
coinciding with the Eastern North Atlantic Water (ENAW) given by
Fiuza and Halpern (1982) with a southern origin. These two
components flow in oposite directions off the Portuguese coast:
the Subpolar component present at levels of more than 27.1 flows
to the south while the Subtropical component less dense and more
superficial « 27.0 sigma-tl flows to the north. This component
has a maximum influence at SW of Portugal and during winter its
presence is decteted at surface as a poleward longshore flow
(Frouin et al., 1990; Haynes and Barton, 1990).
Winds
As part of the Iberian upwelling system, the west Portuguese
coast experiences upwelling-favorable winds from March-April
through October-November (Wooster et al., 1976 ; Fil1za et al.,
1982). During this period , northerly prevailing winds exert
southward wind stress, Ekman transport is offshore and the upper
layer flow to the south (Fiuza,1984). To balance the offshore
transport there are an onshore transport at depth of cold,
2
~
r,'
nutrient-rich slope waters which moves shoreward from depths of
60 to 120m (Fiuza, 1982). From November to February, wind stress
is generally northward, Ekman transport is onshore, and
':,;-~'-P.,.
downwelling occurs. Whenever short-term",7 days (Afonso. Dias,
~='I""',"::·:....::'r·.:,p;c. ), , wind. reversals from the average;:there.,are episodes of
downwelling during the upwelling season and.upwelling during the'
downwelling season.
Hydrography and circulation
•
In addition to local wind forcing, upwelling patterns off
Portugal are also determined by the coastal morphology and the
shelf/upper slope topography as pointed out by Fiuza (1983). On
the wide and flat northern shelf (Figure 1), upwelling is fairly
two-dimensional with upwelling centers 'near the coast and a
probable upwelling front at the mid-shelf (Fiuza, 1983). Off the
southern part of the west coast three-dimensionality results in
the Bay of Setubal which is induced by large coastal protrusions
in association with the pronounced submarine topography of the
Lisboa-Setubal canyons; south of the cape of Sines, where the
topography is more even, the shelf is very steep with virtually
no shelf break, the upwelling pattern is more regular and the
thermal gradients are compressed towards the shore. At the
meridional coast, upwelling occurs occasionally under western
local winds. However, during north wind cyclesj which may not
even reach this southern area, upwelled waters from the west
coast may be impinged over the southern shelf break by an
easterly extension of an apparent equatorward coastal upwelling
current (Fiuza, 1983).
MATERIAL AND METHODS
•
Zooplankton biomasses were determined based on sampIes
collected from August 1985 till January 1989. Two sets of data
were used. One fron sampIes collected in surveys covering the
entire coast in August 85, November 85, January 86 and
March/April 86 and the other from sampIes collected monthly from
October 1986 through January 1989 with few interruptions. In the
first set, th~ zooplankton was collected in a geographically
fixed grid (Figure 1) of 110 hydrographie stations, within a
depth range of 20 m ~o 1000 ~, using 1 m diameter and 5 ~ long
~ing nets with a ~esh aperture of 505 pm, and information on the
stratification of the water column was obtained with a Mansen
bottle. The second set come from sampIes collected along
transepts perpendicular to the coast line within a depth range
of 20 m to 200 m (Figure 1). The regions surveyed were Peniche
3
,
and Figueira da Foz at the northern coast, Sines at southwest and
Lagos in the south. The sampling gear was a 0.6 m diameter Bongo
net with mesh sizes of 505 and 335 ~m and information of the
water column temperature was obtained with a bathytermograph.
Zooplankton was collected by standard oblique net tows as
described by Smith and Richardson (1977) from the surface down
to a maximum depth 200 m and back to the surface and the volume
of the water strained for each net was determined using
calibrated flowmeters. Total zooplankton biomass was determined
by volume displacement, after removal of large (>1 cm) organisms,
and the va lues for each net were expressed as ml/1000 m3 • The
night-day difference in the zooplankton standing stock due to the
time of sampling was corrected by multiplying the value of the
day by the night/day ratio and the values were log. transformed.
RESULTS AND DISCUSSION
Winds
Monthly upwelling indices obtained during the years of the
sampling, 1985 through 1989, are shown in Figure 2. Positive
upwelling
indices
result from northerly
winds.
According to
U.I. (m3/s/100m)
70 r--~--:"-'---~---------------,
this Figure upwelling
60
indices were positive,
50
40
i.e.,
upwelling
30
favorable, in general,
20
during Spring, Summer
10
o l-rl-a.U..lLllJ-.-J.d.
and Autumn.
-10
-20
-30
-40
-50
-60
-70
Hydrography
and
circulat:ion
_
Cabo CarYOeiro
The result of the
c==J Pt.: 4<l.5 N. 11.0 W
upwelling
favorable
JMMJSNJMMJSNJMMJSNJMMJSNJMMJSN
winds
over
the
1985
1986
1987
1988
1989
oceanographic
Monthly upwelling indices
conditions
can
be Figure 2.
during the years of sampling. (Months of
observed during the seasonal surveys - open arrows: limits
August/September, 1985 of monthly sampling - filled arrows)
survey, when a typical
picture of the distribution of the sea-surface isotherms during
the upwelling season was obtained (Figure 3). Surface cold
inshore waters (3 C colder than offshore ) and bottom contour
parallel isotherms in the western coast, reveal that the
upwelling process was undergoing in the entire western coast
under northerly winds with some intensification at the south of
u...u.-U..J...LJ..J..u..wl.ll.J~-U..J...LJ..J..LL.LLLUl.ll.J~.LLI...LJ..J..LL.LLLU~.ll..l..ll.JJ
0
4
•
•
•
',
...
•
the capes~ In the southern coast, a tongue, from what seems to
be an easterly extension of the west coast upwelledcold waters,
was evident. The water column was strongly stratified and deep
dense waters reached the surface near the coast as it may be seen
in Figure 4. T-S diagrams of the outer stations (Figure 5) follow
the Subtropical and Subpolar components of the ENAcW represented
in the Figure by the lines referred as ENACW~ and ENACWp
respectiv:elf (ENA~p - according to Sver~rup et ~l. (1942):
ENACW~ ~ according to Fiuza and Ha1pern (1982». Figures Ga and
6b represent the vertica1 distribution cif density at.tbe most
northern (Caminha) and southwest (Arrifana) sections. These
Figures a10ng with Figura 5, reveal that the sUbtropical
componerit, present at density levels of 1ess than 27.0, occupies
most of the upper 1ayers (250 m) of the water co1umn in the
southern region (Figure Gb) and extends its influence til1 the
northern most section (Figure Ga) where it is present in the
upper 100m depth levels. More dense, higher than 27. i, the
subpolar comporient is present at deeper levels, from 120 m in tlie
north (Figure Ga) till the 300 m depth in the southern regions
(Figure Gb) ~
Three months 1ater, in November/December, i985, sea-surface
isotherms in the northern coast were still parallel to the cost
1ine (Figure 7) but the gradient-was not as strong as in August~
During this cruise the southwest coast was not sampled due to bad
weather conditioris; The winds were mainly from the southwest but
after a day of norther1y strong winds there was upwe11ing cif deep
dense waters as it may be seen in Figure 8 that represents the
vertical distribution of density a10ng the section off Figueira
da Foz. According t6 the T-S diagrams of the outer stations
(Figure 9) there was some thermal stratification in the upper
100m of the water co1umn. The Subtropical comporient of the ENACW
invade all ~he northern she1f while the Subpolar component was
present at deeper levels •
In January, 1986, the distribution of the sea surface
temperature (Figu~e 10) indicate that the subtropica1 warm water
aproched tlie coast from the south, causing at the southern coast
a strong thermic front. This is confirmed by the distribution of
the high sa1inity 1ines in Figure 11 that represents the vertical
distribution of salinity at the most soutliwest section. During
this cruise tlie water column was not therma11y stratified as it
might be seen iri Figure 12 which represents the T-S diagrams of
the outer stations. This Figure show the influerice of low
salinity waters due to runoff in the northern region of Portugal
(stations 2, 12 and 13) whi1e in the southern region the
S~btropica1 component rcached the surface. This componerit was
also present through most of the upper 1ayers of the northern
5
coast as indicated by the position of the 27.0 sigma-t line in
Figure 13, that represent the vertical distribution of the
density along the northern most section (Caminha).
The distribution of the sea-surface temperature during the
March/April, 1986 cruise, is shown in Figure 14. The warm waters
of the Subtropical component of the ENACW still approached the
coast by the south. This is confirmed by the vertical
distribution of the more saline waters in Figure 15 which
represent the vertical distribution of salinity at the most
southwest section. The upper layers of the water column were
still vertically homogeneous and there was a progressive
influence of low salinity waters due to runoff till the latitude
of Lisbon, as may be seen in Figure 16 where the T-S diagrams of
the outer stations is represented.
South of Lisbon the
subtropical component reached the surface. This component do not
reached the northern section as shown by the position of the line
of 27.1 sigma-t in Figure 17 that represents the vertical
distribution of density along the section off Caminha.
Zooplankton spatial distribution
The spatial distribution of the zooplankton biomass during
the Summer of 1985, when upwelling was active through most of the
coast, is represented in Figure 18. In the northern shelf (north
of Lisboa) the lines of equal zooplankton abundance seemed to
indicate southern advection as a result of the establishment of
a southward flow during upwelling. Zooplankton was abundant in
the north and over the mid-shelf in what seems to be a
convergence front. In the southwest shelf there was no apparent
pattern in the distribution of the zooplankton with exception at
the south where the low values seemed to related also with the
advection of the upwelled waters in the cape. To the southeast
the highest zooplankton values were found near the coast.
In late Autumn,
23 November/2 December,
1985,
the
zooplankankton concentration off the northern coast (Figure 19)
was higher in the north and over a broad band over the mid-shelf.
Al though the wind where not upwelling favorable during the
cruise, the broad band could resul t from offshore advection
caused by a day of northerly strong winds that blew when this
region was sampled. In the south there was no particular pattern
in the zooplankton distribution.
In January, 1986, when the subtropical component of the
ENACW most influenced the southern coast, zooplankton was
abundant offshore at the southwest and approached the coast at
the southeast (Figure 20). In the northern shelf zooplankton was
more abundant at the north.
The distribution of zooplankton in March/April, 1986,
6
•
(Figure .21), was similar to the distribution found in January.
Although the abundance of zooplankton was higher, it was alsoconcentrated offshore at the southwest and near the coast at the
southeast seeming·,to .. be !transported to the north~ In the northern·:,~:-:"·;T~~:.-....
.... coast zooplankton ··was abundant over the shelf.
., .. ,..... .In the attempt to confirm the existence of a convergence zone
over the northern shelf the data from th~ monthly sampling at
Espinho and Figueira da Foz were also used. Oue to the short-term
wind reversals during the upwelling season it was expected that
the presence of a convergence zone would be indicated by higher
biomass means and higher coefficients of variation. Figure 22
represents the result of the mean zooplankton biomass and the
coefficient of variation at each station at the Espinh6 and
Figueira da Foz transepts.
•
Coefflclent cf varfation 150~
ESplNHO
ESPlNHO
(a)
(b)
125~
78~
100
~
31 24 "f1
~o
1--~-""""------"'-"--~5~
~
31 24 "f1 10 3
3
Cletance offshore (km)
bIorMae
Distanee otfahore (km)
,
ur'
,/
"
Coeffld8nt of variation 1 ~
(m1/1000m3) 280
18A
E'''''.t):E
CA E~~I
251'~?1
(C
1 -------1'~.? 21,'
1
1---~
FIGL.:EIBA pA FQZ
200
100"4
150
"
100
I--.::-_........_--.---Jil=~..-.....--+~
j-.J.J:~-'----.----~-.---+50
82
47
33 25 "f1
8
2
47
Dlatanee ottehore (km)
33 2S "f1
8
2
Dlatanoe offahore (km)
Figure 22. Average biomass [(a) and (c)], and coeficients of
variation of the biomass [(b) and (d)] along the sections off
Espinho arid Figueira da Foz. (Dashed line - 335 ~m mesh sizei
continous line - 505 ~m mesh size)
In both transepts the mean biomass (Figure 22a and 22c) of the
snaller organisms (>335 ~m) were higher than the larger (>505 ~m)
while the coefficients of variation behave inversely (Figure 22b
and 22d). with exception of the last station at the transept of
Figueira da Foz the biomass distribution along the two transepts
were similar with an increase to the large of the biomass of the
larger organisms while the smaller organisms were more abundant
in two regions, near the shore and before the shelf break. In the
7
transept of Figueira da Foz where the last station was over the
shelf break both biomass deereased sharply. The biomass
eoeffieient of variation eollected by the two nets behave
similarly along the transepts with higher values ,near the coast
and at mid-shelf.
CONCLUSIONS
The hydrologie charaeteristies of the eoastal waters off
Portugal during the studied period presented a systematic north
to south gradient. The thermohaline field was eonditioned by the
Subtropical component of the Eastern North Atlantie Water that
strongly influeneed the southern eoast with warmer and' more
saline waters and diminished its influenee to the north. Seasonal
variation was due to eoastal upwelling, run-off and to the
seasonal cycle of thermal stratif ication (Summer and late Autumn)
- vertical conveetion (Winter and early Spring). In the northern
eoast, with a large and flat shelf, these three last aetions were
determinant.
The spatial variation of zooplankton seemed to be strongly
related to those hydrologie eharaeteristies, to the eireulation
pattern of the upper layers, to the topography of the eoast and
eontinental shelf and to the Ioeal wind foreing.
The southwest eoast, with a very steep sheif and virtually
no shelf break, is very mueh influeneed by the Subtropieal
eomponent of the ENACW in its northward flow. During winter and
Spring this eomponent approaehed the eoast and preserve is
thermohaline eharaeteristies at the surfaee (Figures 11 and 15)
transporting notieeable amounts of zooplankton (Figures 20 and
21). On the wide northern shelf, zooplankton distribution shows
strong dependenee on the wind regime, with a probable convergenee
front at mid-sheif during the upwelling season as indieated by
the high eoneentration of zooplankton (Figures 18, 22a and 22e)
and high eoeffieients of variation of the biomass (Figures 22b
and 22c). This offshore eonvergence front may be associated with
the sinking of phytoplankton populations and eonsequent inerease
of zooplankton between a possible two eells of cross-stream
eireulation as suggested by Walsh (1976) for the wide shelf areas
of the Atlantic eastern boundary currents.
ACKNOWLEDGE
This work was supported in part by Junta Naeional de
Investiga9äo Cientifiea e Teenol6gica (Proj. n 87344jMar). I am
8
•
~
•••
,I
:. I • ,
'.' , "
~ .. ~.',
.,
(·'1 t
i
~\
•
indebet to C.M •. Afonso Dias for the data on upwelling indices. and
to my coileagues who participated in the collection' and
processing of the samples ~ . .
I .
• •
.
"
BIBLIOGRAPHY
•
cunha, M~E •• Moita, M.T., 1991.
Fiuza, A.F.G., 1982 • The Portuguese coastal upwelling system.
In Actual problems of ocenography in Portugal, edited by Junta
Na~ional de Investiga9äo Cientifica e Tecnol6gica, pp •. 45-71,
Lisboa.
.
... - - ,
Fiuza; A.F.G~, 1983. Upwelling patterns off Portugal. In Coästal
Upewlling. Its sediment record, Part A, E.Suess e J. Thiede
(ed~), pp. 58-98, Plenum Press.
Fiuza, A.F~G., 1984~ Hidrologia ediriämica das 4guas costeiras
de Portugal. :Ph.D~ dissertation, Universidade Cl4ssica de LisbOa,
294 pp.
Firiza, A.F.G., Halperri, 0., 1982. Hydrographie obserVations of
the canary Current betweeri 21·N and 25.S·N in March/April 1974.
Rapp. P.-v; Reun. Cons. int. Expior. Mer, 180, 58-64.
Fiuza, A.F.G.; Macedo M.E., Guerreiro H.R., 1982. Climatological
space and time var~at~on of the Portuguese coastal upwell~ng.
OCeanologica Acta, 5, 31-40~
Frouin, R;, Fiuza, A.F.G., Ambar, I., Boyd, T.J., 1990.
Observations of a poleward surface current off the coast of
Portugal and spain during winter. J. Geophys~ Res., 95, 679-691.
HaYnes, R., Barton, E.D.; 1990. J. Geophys. Res., 95; 11.42511.441.
sverdrup, H.U., Johnson, M.W., Fleming, R;H., 1942. The oeeans.
prentice-Hall, inc~,.New York, 1060 pp.
smith P., Richardson S.L., 1977. standard techniques for pelagic
fish eggs arid larva surveYs. FAD Fish. Tech~ pap., 175, 100pp.
Walsh, J.J~,' 1976; Herbivory as a factor in patterns of nutrient
utilization in the sea. Limnology and OCeanography, 21, 1~13.
Wooster W.S., .Bakun A., McLairi D;L., 1976. The seasonal upwelling
cycle along' the eastern boundary of the North Atlantic. J. Här~
Res;, 34, 131-141.
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• •• JFIGUEIRA DA FOZ
• ••••
41
40
40
52
39
39
• •
65.•••
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'1. SINES
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8?.lJ u.J~OS FARQ.-·~. -----, 37
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.L~
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97
98
109
0o/>.
-"'./
36 " - - - - - ' - - - - - - - - - - - ' - - - - - - 36
11
10
9
8
7
Figure 1. Location of stations and depth contour of the
shelf break (200m). (Dots - seasonal surveys: stars monthly sampling)
•
LONGITUDE (O-\\T)
42
11
10
9
8
41
•
7
42
r----r----~--_,__--___,
41
21 Aug./3 Sep .
1985
.--.., 40
Z
0
-.......--
40
Temperature (OC)
o
r:Ll
m
Q 39
39
:=>
~
I---l
~
<C
•
.....::l 38
38
37
37
.......
.-..J.
0
CD
o
36
.-NN
<00..000
36
'-------'-------'----~----'
11
10
9
87
Figure 3.
Sea-surface temperature off the Portuguese
coast from 21 August till 3 September, 1985.
/
o
100
79
Distance offshore (km)
66 61
-t-t
30
17
-t
~~f.?;j'
,-7.0~
-..
Figueira da Foz
S
'-"
Sigma-t
.c
....., 200
p..
llJ
Q
23/24 Aug. 1985
" .............
300
400 l - -
-I.-
----l
Figure 4. vertical distribution of densi ty along
the section off Figueira da Foz. (Quter station
number: 26)
•
24.0....----------------------,
109
22.0
20.0
.........
u
~
18.0
Ql
.....
~ 16.0
.....
Ql
a.
•
E 14.0
<D
~
12.0
10.0
ENACW P
35.50
36.00
-
36.50
37.00
Salinity
Figure 5. T-S diagrams of the outer stations, 21
August - 3 September, 1985.
Dislance offshore (km)
57
31
4-4
15
1
or-----:----::~':0':~~~~~:::::::::::;:;___,
100
~~j-~~~
_~.: ~ .._.. _~ ....... _.. :~ , ......l'
]
..c:: 200
.....
Caminha
Cl,
Sigma t
CL>
Cl
21/22 Aug. 1985
300
•
400 ' - - - - - - - - - ' - - - - - - - - - - - - - - - '
Figure 6a. Vertical distribution of
density
along
the
section
off
Caminha. (Outer station number: 2)
Dislance offshore (km)
o r--_ _-'5:..:6_==-42;,.--.-:-:-""7.2~9-...;;2..:..0_-=;::---::1~---,
'~~~::::::';
...... -_.,
100
..
.: "///0
~
.§,
•
Arrifana
..c:: 200
.....
Sigma t
Cl,
CL>
Cl
...
.............
...........................
28 Aug. 1985
300
400 ' - - - - - - - - - - ' - - - - - - - - - - - - '
Figure 6b. vertical distribution of
density
along
the
section
off
Arrifana. (Outer station number: 85)
/
LONGITUDE (OVV)
42
11
10
9
8
7
42
.------.,-----~---.,-------,
41
41
23 Nov./2 Dez.
1985
___.40
Z
0
40
Temperature (Oe)
-.....-'
o
~
m
•
39
Cl 39
~
E--i
t--i
~
<r:
~ 38
38
....r----~ _
37
\<6.'
36
F
_ AR
'<ir-'
~ ..
\1.~/:
:
:
n
.
\ 1. .
l . - -_ _- l - -_ _- - l .
11
10
9
.
-l........C--
8
37
.
36
7
Figure 7.
Sea-surface temperature off the Portuguese
coast from 23 November till 2 December, 1985.
•
Distance offshore (km)
79
66 61
44
30
17
4
o r-~--~.~.~.------=c..:----':;..;=---=-...'----_,.........:.~-___;
.
:~ :
.
.
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a
/
... , f
•
:i~~~(~~~~~~~~~~:~~~:::~::<::··::7.-:·
_.. ---------'
100
..:
__ •...,:.
...
_,..--_ .. -----
Figueira da Foz
Sigma-l
..r:: 200
-.J
0..
aJ
o
27/28 Nov. 1985
300
400
l..--
----!
.l--
Figure 8. vertical distribution of densi ty along
the section off Figueira da Foz. (Outer station
number: 26)
::·:1
20.0
~
~ 18.01
..a.
ö 16.0
Q)
E 14.0
Gl
~
12.0
10.0
1
.
8.0
35.00
ENACW P
i
I
i
35.50
35.00
Solinity
35.50
37.00
Figure 9. T-S diagram of the outer stations, 23
November - 2 December, 1985.
LONGITUDE (o\V)
42
11
10
9
8
7
r------.---_~--_r_--_
42
41
41
·l· .PORTUGAL
.. ~.
~.
~40
Z
J
21 Jan.j5 Feb.
a
... ::f"
o
'---"
.
Q 39
::J
40
1986
Temperature (OC)
0 m
...
BOA
•
39
t-
t---;
E--
-<:
~ 38
38
...
a
~' .
......,.,
[
FAR
.....L.~
'~~~5.~:14:5
37
15.5 ~~'l.Q:U ~:
16.0
36
l . - -_ _---l...-
11
10
.~
.~
'\
15.5·
l . - -_ _----l.-._ _- - - J
9
8
37
36
7
Figure 10.
Sea-surface temperature off the Portuguese
coast from 21 January till 5 February, 1986.
•
Distance offs hore (bl
~: ~
f :
.
}; \') ;6)00 : .
100
.t:. 200
0.
Q>
r
.
!.
/ -g
. (. )
6~"""':"
~~~9'>
.~_.
. .'
Arrifana
/"':"
Caminha
Salinity
Sigma-t
Q
02 Feb. 1986
300
300
4001.-------'-:.-----------'
•
21 Jan. 1986
Figure
11.
Vertical
distribution of salinity along
the
section
off
Arrifana.
(Outer station number: 85)
24.0
4OO1.-_ _--l-
.-.l
Figure
13.
vertical
distribution of density along
the section off Caminha. (Outer
station number: 2)
I
22·°1
20 0
. ]
S 18.0
0
Q)
~
16.01
~
E14.0
~
Q)
•
=.-2
_
Q)
~
12.0
10.0
ENACW P
35.50
36.00
36.50
37.00
Solinity
Figure 12. T-S diagrams of the outer stations,
21 January - 5 February, 1986.
LONGITUDE (Ow)
42
11
9
10
8
7
42
.--------.----rr----,----~
41
41
PORT.UGAL
.
20 Mar./4 Apr.
,-... 40
40
1986
Z
,,",
...,
'--'"
Temperature
0 nl
ce)
C::J
('
'J9
i""'- .-J.
•
39
I----
>-J
.........
r"
"""-l
c-
<
-
\
'J8
•-J
38
... SINES
J-.....
.~
..
:37
37
36 '---_ _
11
10
-l..-
.L----_ _- - ' -_ _- - - l
9
8
36
7
Fiqure 14.
Sea-surface temperature off the Portuguese
coast from 20 March till 4 April, 1986.
•
.
Distance offshore
(~m)
Dlstllnce offs hore (km)
57
o r--_ _.-:5:;:6_-,--:.4::...2_.-:2:;.:.9--:2:..:.0_-=_....:.....,._
(,':;~~.,.,.,_...': ~ '.' .;.. _ .
...-....- .~ i:·(:··(-~~f.O
,: ri
1
100
44
31
15
1
---:;:r..:...;.-:.~-. ~. .:. : .;. /-: :-: . .:.=: ;.:~c: :~-:~.-.~:-~ ~";~: "~" !" ;: :-';";/~' -
~3eöO
)~:)
•
• •. '
• .: I
~q
~~«. tf
.0::
..
200
Q.
-=0'!>"~
Cl
Arrifana
/
"
I
/
Caminha
Salinily
Sigma t
01 Apr. 1986
20 Mar. 1986
300
300
4OQ'--_ _- ' -
---J
4OOL-------'-----------'
Figure
15.
Vertical
distribution of salinity along
the
section
off
Arrifana.
(Outer station number: 85)
U
24.0
j
22.0
I
Figure
17.
vertical
distribution of density along
the section off Caminha. (Outer
station number: 2)
20.01
1
18 0
.
ENt..::W t
,/
~
Ö 16.01
~ 14.0 ~
Q)
I
I-
2
12.0
10.0
ENACW P
35.50
36.00
Salinity
36.50
37.00
Figure 16. T-S diagrams of the outer stations,
20 March - 4 April, 1986.
LONGITUDE (O,r)
42
11
10
9
8
r------r----"..-----.,.------,
7
42
41
41
______ 40
40
Z
0
'---'"
m3 )
......
W
39
Q 39
~
~
~
~
~ 38 -
38
37
37
36 '----_ _
11
10
---.l.-
. l . . - -_ _- - L -_ _- - - '
9
8
36
7
Figure 18.
Zooplankton biomass distribution off the
Portuguese coast, 21 August-3 September, 1985.
•
LONGITUDE (01r)
11
10
9
8
7
42 ,...-------,-----,..,-----,---------, 42
41
41
Jo..
~40
Z
o
•
'--'"
\ C)
~
::l
'J.
40
1985
Zooplankton
biomass
3
Ln(ml/ 1000 m )
'0"
.".- . . .
~
PORTUGAL
LISBOA
039
39
~
t..........
~
<
..-J
i
38
r
38
I
I
•
FARQ.
l.----.J
~~3':
37
36
l - - -_ _---.l.-_ _- - - - l l - -_ _--L-_ _- - - - l
11
10
9
8
37
36
7
Figure 19. Zooplankton distribution off the Portuguese
coast, 23 November-2 December, 1985.
LONGITl-DE (01r)
42
42
·1 ~~'\(
··4· "
41
5
PORTO
JL-'? .
Si"
/7:."
41
.
--...
. . . [.1, ~~~y'%GF~~
r-- 4O
4/
Z
• •
.----
(
o
C::J
\
039
1
.-
3
---'
•
'---
I
C-...
(
0 /
'" CI~BOA
\.
\
~
Zooplankton
biomass
3
Ln(ml/1000 m )
'-',
,/
•
1
0
01
---?
I~
.\
) .
<:l
- 38
.
0
~
J\
o ~o)
•
0
GJ
••
0
l38
<'""1 1N-'-' c;:
~
1:.; .....
~
0
0
J
0
I
~/<
. -!--/. FAR
37
o
L
.
11
10
II
. ~
O
L - - -_ _--l..-
I
J 39
,/"
;?
~
(v
40
1986
.~/
0 '
(>
36
7
8
9
10
11
( ) :
4
"
:
"
'------_ _---.l.-_ _- - - - l
9
37
8
36
7
Fiqure 20.
Zooplankton distribution off the Portuguese
coast, 21 January-5 Februry, 1986.
•
LONGITUDE (OW)
42
11
10
9
8
7
42
,------,----,..-r------,-------,
. . . \. .
)- --~
•'Y'- •
41
0
•
41
;
/
G~
I .
... '!'
.~~
' ,d",'.
) 0J
•
•
0
.
PORTUGAL
20 Mar./4 Apr.
1986
I
•
Zooplankton:
bio/mass.J I
Ln(ml/1000 m ) i
,~
,~~ , . ~
.\
~~ (')L LI/~BOA
'--.,,-1
4
JI 40
J
39
,I ,-J'f'
;
\'-
-'
"'"
. "3':\~ . " L..--r~
'I /
)
(,>,
./
I\
;3-\
i
\ I
3) "!l,.~ ..~c::nTE"
"--' Jll 'i ;:)
/
3
~/\'
38
tOt
J-:::'.
I
:Ja2~3)
.'""
37
37
-,
3
36
L - -_ _---l..-
11
10
---I
- l - _ _----l
9
8
36
7
Figure 21.
Zooplankton distribution off the Portuguese
coast, 20 March-4 April, 1986.