I
OCEANOLOGICA
I
ACTA - VOL. 22 - No1
L--f54
Water column and recent sediment data on
diatoms and coccolithophorids, off Portugal,
confirm sediment record of upwelling events
Fatima ABRANTES ‘, Maria Teresa MOITA
b
a GM-DGM - Instituto Geologico e Mineiro, Departamento de Geologia Marinha, Estrada da Portela, Zambujal, 2720
Alfragide, Portugal
b IPIMAR - Instituto Portugu&s das Pescas e do Mar, Av. Brasilia 1400 Lisboa, Portugal
(Received 7 January 1997, revised 6 October 1997, accepted 22 October 1997)
Abstract - Diatom and coccolithophorid abundance and diatom assemblage composition found in the water column along
the Portuguese margin, during upwelling and non-upwelling conditions, are compared to the distribution patterns observed
in the recent sediments from the same area. The water column results indicate a one order of magnitude increase in phytoplankton biomass during upwelling conditions (summer), with diatoms being the most important contributors. Coccolithophorids, on the contrary, dominate the phytoplankton in winter (non-upwelling). The comparison of the upwelling
and non-upwelling spatial distribution of these phytoplankton groups to their sedimentary record reveals the sediment
record as a reflection of the upwelling situation, preserving most of its original spatial variability. The comparison between
living and fossil diatom assemblages indicates that from the two genera which dominate the summer biologic assemblage,
Pseudo-nitzschia and Chaetoceros, Pseudo-nitzschia is not represented in the sediments, while Chaetoceros is the dominant form of the sediment. Thalassiosira which occurs in the same abundance in both seasons, responding to both river
and upwelling nutrient input, can not be a reliable indicator of any single process. However, this genus distribution in the
sediments can be used as an indicator of continuous nutrient availability.
Such results are of great importance for paleoceanographic reconstructions since they constitute a good indication that the
sediment record, even though somewhat altered with respect to assemblage composition, does reflect the water column
characteristics. 0 Elsevier, Paris / Ifremer / Cnrs / Ird
upwelling / Portugal / diatom / water column / sediment
RCsumC - DiatomCes et coccolithophoridCs dans la colonne d’eau et le sediment et m6moire des upweUings au large
du Portugal. L’abondance de diatomtes et des coccolithophorides et la composition des populations de diatomees ont &tt?
observees le long de la c&e du Portugal dans la colonne d’eau et dans les sediments recents. Pendant l’upwelling (&5) la
biomasse du phytoplancton dans la colonne d’eau augmente d’un ordre de grandeur avec les diatomees. En l’absence
d’upwelling (hiver), les coccolithophoridts predominent. La repartition de ces groupes dans le sediment reflbte la situation
d’upwelling en conservant la variabilite spatiale originelle. La comparaison entre les populations de diatomees vivantes et
fossiles indique que l’un des deux genres dominants en et6 Pseudo-nitzschia, nest pas represent6 dans le sediment tandis
que l’autre, Chaetoceros, y predomine. Le genre Thalassiosira, present avec la mCme abondance pendant les deux saisons
en raison de l’apport de nutriments par le fleuve et par l’upwelling, ne peut &tre l’indicateur fiable d’un processus unique,
mais la presence de ce genre dans les sediments indique la disponibilitt permanente de nutriments. Ces resultats sont d’une
grande importance en palto-oceanographic car ils montrent que le sediment reflete les caracteristiques de la colonne
d’eau, malgre les modifications observees dans la composition des populations. 0 Elsevier, Paris / Ifremer / Cnrs / Ird
upwelling I Portugal 1 diatombe I colonne d’eau I skdiment
Oceanologica
0 Elsevier.
Acta (1999)
Paris I lfremer
22, 1, 67-84
I Cnrs I Ird
67
F. ABRANTES,
M.T. MOITA
I. INTRODUCTION
used by Abrantes [ I ] to describe the relationship between
the hydrography and the diatom species and groups preserved in surface sediments off Portugal. According to
this author, small species of the genus Thalassiosir~r characterise areas of persistent upwelling where availability
of nutrients is more constant and/or higher; Paruliu sulcntu (Ehr.) Cleve appears as an abundant species with
mean cell diameter increasing as nutrient availability
decreases and the resting spores of Chaetoceros Ehrenberg, record the position of the inner upwelling front.
More recently, Moita [17] presented integrated diatom
data (abundance and assemblages composition) for the
top 100 m of the water column for upwelling conditions.
Her results show distribution and abundance patterns for
diatoms, mostly represented by Pseudo-nitzschia, Chaetoceros and Thalassiosircr, reflecting the direct area of
influence of the newly upwelled waters.
Reconstruction of the past productivity in the oceans has
always been one of the most important issues for paleoceanographers, but since the discovery of a one-third
decrease of the atmospheric CO, during the last glacial
age [3] this theme became a dominant one; given that
oceanic productivity is a possible control on long-term
changes in atmospheric carbon dioxide concentration.
In today’s oceans, 50 % of oceanic productivity is estimated to be concentrated in 30 % of the oceanic area, in
margins characterised by the occurrence of coastal
upwelling 141.The observed uncoupling between the primary and secondary producers that occurs in such areas
results in significant export flux to the sediments [ 131.
So, these high sedimentation areas may preserve a great
deal of information relative to the past productivity
conditions. However, to estimate what biological and
chemical characteristics determine the sediment record,
we first need to try to relate the sediment record to modern conditions. Difficulties arise from the fact that the
species generally preserved in the sediments may not be
the ones that dominate the living community. Trap studies reveal a direct relation between the biogenic flux and
productivity variations; however, the same type of data
also shows that only a small fraction of the exported flux
reaches the bottom, and confirms that different biogenic
groups have different probabilities of becoming incorporated in the sediments [7, 14, 24, 281.
Diatoms are abundant in the sediments along the Portuguese margin, but the biogenic component of these sediments is very rich in coccolithophorids.
These
phytoplankters, which are important bloom formers in
low productive warm waters, are however, also consistent
components of upwelling communities 1281. Off Portugal
coccolithophorids mark the southern coast nutrient
enriched summer upwelling waters [ 171.
In this study, we compare two of the published data sets
[l, 171, with new water column data now available for a
non-upwelling situation in order to introduce the possible effect of season into the sediment record as well as to
define and/or check the validity of diatom taxa preserved
in the sediments as indicators of paleoconditions.
Another of the purposes of this paper is to evaluate the
importance of coccolithophorids during upwelling versus non-upwelling conditions, as well as in the sediments.
Even though a great amount of important information,
obtained from trap studies, indicates maximum total
organic carbon and biogenic opal, with diatoms being the
main contributor to these opal fractions, occurring in
association with upwelling conditions, [24,28] that information is precise. A better understanding of the relations
that exist between the sediment record and the water column processes may also be reached by the comparison of
spatial and temporal plankton distributions on the water
column to the spatial distribution of the same plankton
groups in the surface sediments of several upwelling
areas. Such a comparison has to our knowledge never
been attempted before, but it is, in this paper, made for
the Portuguese margin/upwelling system. Absolute diatom abundance patterns found in the surface sediments
collected along this margin [ 11, which is characterized by
the occurrence of seasonal upwelling, reflect the actual
patterns of upwelling described for the area by Fidza [9,
lo] and revealed by the pigment content distribution during upwelling events [27]. Diatom assemblages were also
2. MATERIAL
AND METHODS
Water column sampling was performed on the Portuguese coast, along sixteen to eighteen sections perpendicular to the bathymetry, and up to the isobath of 1000 m,
during IPIMAR cruises CICLOS 1 and CICLOS III.
These cruises were made aboard R.V. Noruegn, from
20 August to 3 September 1985 and 20 January to 6 February 1986, respectively (figures la, 6).
Salinity and temperature were determined at each station
for the following depths: 0, 5, 10, 20, 30, 40, 50, 75, 100,
125, 150, 200 and 300 m (or near bottom in shallow
areas). Samples for phytoplankton analysis and Chloro-
68
SEDIMENT RECORD OF UPWELLINGS
UPWELLING
NON-UPWELLING
Figure 1. Sample location in relation to regional geographic features. a- Water column summer cruise of August 1985 - CICLOS I;
b- Water column winter cruise of January 1986 - CICLOS III; c- Sediment samples: small circles - surficial samples; larger circles - Faegas IV
core-tops.
phyll-a determinations were collected at the same discrete
levels down to 100 m. Temperature was determined from
reversing thermometers coupled to Nansen bottles, and
salinity (conductivity) was determined using a salinometer
BECKMAN Mod. RS7-C. Phytoplankton samples were
preserved with hexamethylenetetramine buffered formalin to a final concentration of 2 % and counted under an
inverted microscope, with phase contrast and brightfield
illumination, using 100 mL composite settling chambers.
Samples from each depth were integrated into one sample
per station representing the water column (water samples
from each depth were mixed in proportion to the extent of
water column that they represented). Chlorophyll-u was
measured by fluorometry (Perkin-Elmer Mod. 204-A)
after extraction in 90 % acetone.
Group of the University of Bordeaux) (figure Ic). Procedures for the treatment of raw material, preparation of
slides, diatom quantitative analysis and definition of
counting units are described in Abrantes [2]. Specimens
were identified and counted generally to the species level,
and its abundance calculated as a percentage of total diatom assemblage.
Coccolithophorids abundance was determined in the
< 20 pm sediment fraction, by evaluation of the percentage area of a smear-slide occupied by the group.
When defining the diatom assemblages, the genera
Chaetoceros and Thalassiosira were treated as groups,
even though species were counted separately as much as
possible. Chaetoceros species are grouped because their
presence in the sediments is mainly in the form of resting
spores, most of which cannot be assigned to the vegetative form which generated them. On the other hand,
Thalassiosira species are grouped due to the difficulty of
properly identifying of the smaller specimens (< 12 urn)
present in the water column using the inverted
microscope.
The sediment samples were collected during cruises
AC75/1, AC76/1 and AC77/2, conducted by the Department of Marine Geology of the Geological Survey of
Portugal aboard R.V. Almeida Carvalho. SurBcial shelf
sediments were collected with a large Van Veen grab and
the slope samples are core-top samples from piston cores
collected in October 1982 (Faegas IV - Marine Geology
69
F. ABRANTES, M.T. MOITA
3. HYDROGRAPHY
According to Filiza [ IO] the upwelling source water is the
Eastern North Atlantic Central Water (ENACW), a subsurface water mass generally present below 100 m and
composed of two branches of different origin and thermohaline characteristics. Rios et al. 1221 designated these
two branches by Subtropical Eastern North Atlantic
Water (ENAWt; CJL< 27-27. I) and Subpolar Eastern
North Atlantic Water (ENAWp; 27.1 < ot < 27.3), and
consider that ENAWt overlays ENAWp. South of the
NazarC Canyon ENAWt is the upwelling source water,
but decreases in importance towards the north where,
depending on the wind strength, both branches can be
upwelled.
Upwelling takes place along the west coast of Portugal
from April to September under the fairly strong and
steady northerly “Portuguese trades” [9, 10, Ill. Based
on the analysis of a series of thermal infrared images,
Filiza [9] considers the existence of three main areas,
which are characterised by different upwelling patterns.
In this respect the west coast, the area north of Nazar6 is
characterised by an homogenous upwelling along the
shore. From Lisbon to Cape Sines, the upwelling structure is complicated both by the presence of coastal protrusions and the Lisbon and Setdbal Canyon. South of
Cape Sines, the upwelling structure becomes more regular again, but the shelf water is strongly affected by the
warmer and saltier offshore surface waters. On the
Algarve coast, upwelling only takes place occasionally
when westerly winds occur, but the west Algarve margin
gets covered by western upwelled waters carried around
Cape St. Vincent, along the shelf break, during upwelling
events. This coastal upwelling brings to the surface
waters which have slightly different characteristics from
south to north, suggesting different sources [9, IO, 221.
In this paper, cruises CICLOS I (summer) and CICLOS
III (winter) are considered to represent an upwelling and
a non-upwelling season, and the hydrographic conditions
found at each time are as follows:
CICLOS I . Patterns of sea surface temperature distribution in the area are presented in ,figure 2n and in the
NOAA-9 satellite image f$gure 2b). The isotherms,
which run parallel to the west coastline, reveal a cross
shelf gradient of 5 “C and the presence of the coldest
waters near the shore and south of the capes. In the Cape
Chl-a (mg/m3)
Ssr(OC)
Figure 2. a- Sea surface temperature (“C) CICLOS I - August 1985; b- Tiros-N thermal infrared image obtained during the summer of 1985
(26 August 1985). (Courtesy of A. Fiuza, Institute of Oceanography - University of Lisbon): c- Chlorophyll-a surface distribution (mg m“)
CICLOS I - August 1985.
70
SEDIMENT RECORD OF UPWELLINGS
UPWELLING
NONGPWELLING
SEDI~NTS
Figure 3. a- Sea surface temperature (“C) CICLOS III - January 1986. b- Salinity distribution CICLOS IIl - January 1986. c- Chlorophyll-u
surface distribution (mg.m-3)CICLOS III - January 1986.
S. Vincent
area, the upwelling
ture, which develops in these shallow coastal waters at
the end of fall, when the whole water column begins to
cool as a result of net heat loss from the surface; an idea
corroborated by the presence of waters of subtropical
origin (ot < 27.0) in the upper 200 m along most of the
coast. An exception to this water column homogeneity
was observed to the north of the Nazam canyon where
surface stratification probably caused by river runoff was
detected in the upper 50 m @gure 7b).
waters turn anticlockwise
around the cape flowing eastward, following the pattern
described by F&a [9]. North of the Nazare canyon, the
shelf was occupied by a shallow lens of reduced salinity
water limited below by the seasonal pycnocline
(figures 4, 5, 8 in [17]). The innermost 10 to 30 km are
characterised by an uplifting of the upper 40 m isotherms
and isopycnals, sometimes reaching the surface (figure 5,
F. Foz in [17]). Along the south-western coast, and specially at Cape S. Vincent, upwelling was particularly
intense, with waters from 50 to 120 m rising to the surface (figure 6, Sagres in [17]), a situation which has also
been observed even during moderate upwelling events
(F. Sousa, pers. comm.).
4. RESULTS
4.1. Phytoplankton
CICLOS III . During the winter cruise, sea surface temperature distribution shows a one degree gradient
between coastal and offshore waters all along the northwestern coast (figure 7~). Adjacent to the south-western
and Algarve coasts, SST distribution shows a zonal distribution of isotherms with a 2.5 “C gradient between
inshore and offshore stations, a gradient also present in
the salinity distribution. The existence of this colder
water band is, however, not due to coastal upwelling
yigure 7b). According to Filiza [lo] this is a general fea-
biomass
During the summer, phytoplankton biomass in the upper
100 m, measured as chlorophyll-a (chl-a) concentration,
is distributed according to the patterns of sea surface
temperature, with the coldest upwelled waters near the
coast being phytoplankton enriched (figure 2~). During
winter, chl-a is low and constant along the entire coast,
ranging between 0.1 and 1 mg.m-3 @gut-e. 7~). Summer
values, near the coast, are ten times higher than observed
during the winter, reaching 5 mg.me3 north of Port0 and
71
F. ABRANTES,
M.T. MOITA
NONdJPWELLIffi
UPWELLING
32
Figure 4. Distribution
January
of the water column
averaged
1986; c- Distribution
of the diatom abundance
abundance
of diatoms
(log cells/L);
in the sediments
(number
valves/cc
3 mg me3 at Cape S. Vincent. Offshore waters do not
show a significant difference between the two seasons.
a- CICLOS
I - August
of fresh sediment).
1985;
b- CICLOS
I11 -
Figures 4a and b represent the relative abundance of diatoms within the total phytoplakton community during the
two sampled seasons, summer and winter respectively.
From the observation of these figures, the indications
given by the total abundance are confirmed with diatoms
appearing as the major contributor to the summer phytoplankton community at the temperature defined
upwelling centres; that is, in the inshore area north of
Nazare and around Cape S. Vicente. The poor contribution of this group to the winter phytoplankton is also
clearly illustrated.
4.2. Diatoms
4.2.1. Water Column
The distribution of diatoms during the summer cruise
follows the patterns of sea surface temperature and chl-a
being important contributors to the general productivity caused by the occurrence of coastal upwelling
(figures 2a, c, and 3a). Water column abundances nearshore varied between 7 x IO5 cells/L off Port0 to 2 x lo5
cells/L off Cape S. Vicente, in the range observed in other
upwelling areas [6, 8, 151. Offshore, the abundance of
diatoms is similar in both seasons, ranging from 30 to
3 x lo3 cells/L. Two distinct maxima are however
detected north of the Nazam Canyon during the winter
cruise. One of the maxima, 4 x lo4 cells/L occurs nearshore between surface salinities of 34 and 35, while the
second maximum (2 x lo4 cells/L) appears towards offshore, bordering the front of haline origin (figures 3b, 7b).
The diatom genera which dominate the water column
during the summer period, showing maxima at the
upwelling centres are Pseudo-nitzschia H. Peragallo and
Chaetoceros Ehrenberg (lo5 cells/L) (figure 11 in [17];
Appendix la and figure 6a). Thalassiosira Cleve and
Thalassionema nitzschioides (Grunow) Hustedt follow
the major taxa distribution pattern, but have abundances
one order of magnitude lower (10’ cells/L) (figures 6d,
g). In winter, when total diatom abundances are three
orders of magnitude lower, Pseudo-nitzschia and Chaetoceros abundances decrease by three and two orders of
72
SEDIMENT RECORD OF UPWELLINGS
UPwELuNG
NON-UPWELLING
n ,I
Figure 5. Distribution of the water column relative abundance of diatoms (% of total phytoplankton community); a- CICLOS I - August 1985;
b- CICLOS III - January 1986.
Thalassionema
Cleve (figures
magnitude respectively, while Thalassiosira
and Thalassionema
nitzschioides
appear as the dominant forms
maintaining the summer abundances ( lo4 and lo3 cells/L
respectively) (Appendix lb, figures 6b, e, h). However,
these two taxa show quite different distribution patterns,
while Thalassionema
nitzschioides
is homogeneously
distributed all along the shelf, ThaZassiosira is clearly
more abundant north of Nazare (fisures 6h, e).
nitzschioides
6i, 1).
and Paralia
sulcata
(Ehr.)
4.3. Coccolithophorids
4.3.1. Water Column
Coccolithophorids are widely distributed, but more abundant to the south of the Nazare canyon in both summer
and winter sampling periods (figures 6a, b). During summer, the highest concentrations, more than 3 x lo4 cells/
L, are associated with upwelling and occur at Cape
S. Vincent. North of NazarC, this group is mainly distributed at mid and outershelf, with the lowest numbers
(~10 cells/L) observed at the innershelf stations. In winter, concentrations of the same order of magnitude of the
summer maxima (lo4 cells/L) are only present in some
minor dispersed patches, on the southwestern and south-
4.2.2. Sediments
The distribution pattern of diatom abundance (number/
c.c) in the sediment samples of the Portuguese margin
(Appendix lc; figure 3c) shows generalised high abundance of diatoms on the northern part of the shelf (5 x lo6
valves/c.c.) and a band of high values (lo6 valves/c.c.)
that runs parallel to the southern coast and extends along
the Algarve coast, immediately to the east of Cape
S. Vicente.
em coasts.
If, instead of the total abundance of cells, the relative
importance of coccolithophorids in the phytoplankton
community [% Coccolithophorids = (number cells of coccolithophorids/l) / (total number of phytoplankton cells /
L)] is considered (figure 8a, b), we find that during the
In the sediments, the diatom taxa which appear as dominant are Chaetoceros
resting spores and Thalassiosira
spp. (figures 6c, j). Also present in lower abundance, but
with a more homogenous distribution along the shelf, are
73
F. ABRANTES,
M.T. MOITA
NON-UPWELLING
UPWELLiNG
SEDlMENTS
Chaetocerus
17
2
/
Thalassiosira
---v---I
1:
If
to
-
Figure 6. Distribution of the water column abundance (log cells/L) of Chaetoceros.
a- CICLOS I - August 1985: b- CICLOS III - January 1986; c- Distribution of the percent abundance in the sediments
Distribution of the water column abundance (log cells/L) of 7%alassio.siru.
d- CICLOS 1 - August 1985; e- CICLOS III - January 1986; f- Distribution of the percent abundance in the sediments.
74
SEDIMENT RECORD OF UPWELLINGS
UfWELLlNG
NONG’WELLWG
ThpRssrjbnamp,..-,,
.,
I.. 11 M
Figure 6 (continued). Distribution of the water column abundance (log cells/L) of Thalassionema
nifzschioides.
g- CICLOS I - August 1985; h- CICLOS III - January 1986, i- Distribution of the percent abundance in the sediments.
Distribution of the water column abundance (log cells/L) of Paralia sulcata.
j- CICLOS I - August 1985; k- CICLOS III - January 1986; l- Distribution of the percent abundance in the sediments.
75
F. ABRANTES,
M.T. MOITA
SALINITY
CM-a (mg/m3)
iJ c-----’
1
Figure 7. Distribution
b- CICLOS
III - January
of the
1986.
water
column
averaged
abundance
of
cells/L).
a- CICLOS
1 - August
1985;
When the same type of comparison is made for the
coccolithophorids (upwelling, non-upwelling and sediments,figure S), the low abundances in the north and the
highest values in the zone immediately to the north of
Cape S. Vincent, observed in the sediments, reflect not
only the general N-S difference observed in the water column for both upwelling and non-upwelling situations, but
also the summer water column distribution @gure 8~).
4.3.2. Sediments
Higher abundances of Coccolithophorid are found on the
southwestern and Algarve coasts, while low abundances
characterize the northern part of the shelf figure 8~).
Our water column data are reduced to two discrete periods of specific seasons, not representative of the interannual variability and certainly not of the same range of
scale of the sediment record. However, assuming their
representativeness of the biologic interseasonal variability, one can say that the diatom and coccolithophorids
abundance distributions observed in the sediments is
mainly a reflection of the water column distribution
observed during an upwelling situation. lvIoreover, both
5. DISCUSSION
abundances
(log
non-upwelling situation (figure 3b, ~1)to the diatom abundances distribution in the surface sediments figure 3c),
the main observation is that the sediment distribution pattern is closely related to the water column upwelling situation, but does not show any relation to the winter water
column distribution.
upwelling period, their importance is significantly
reduced in the areas influenced by the upwelling phenomena. Higher relative abundances occur associated with
warmer waters (figures 2a and 8a). During the nonupwelling situation, this group composes up to 90 % of
the total phytoplankton community all along the south and
western coasts, except for the north inshore area (Figueira
da Foz to Caminha and up to the 100 m bathymetric),
which corresponds to the area of lower salinity (figure 7b).
5.1. Diatom and Coccolitbphorid
Water Column versus Sediments
coccolithophorids
-
If we compare the diatom abundance distribution patterns
in the water column for a typical upwelling period and a
76
SEDIMENT RECORD OF UPWELLINGS
lwN4JPwELLIffi
Figure 8. Distribution of the water column relative abundance of coccolithophorids (% of total phytoplankton community).
a- CICLOS I - August 1985; b- CICLOS III - January 1986; c- Distribution of the coccolithophorids abundance in the sediments (8 slide area
covered by coccolithophorids).
groups’ distribution patterns in the sediments preserve
most of their original biological spatial variability, independently of the sediment lithology and/or the relative
importance of the several geologic processes known to
act on the Portuguese shelf [ 181. This indication, that
both diatom and coccolithophorids produced during
blooms are preserved with greater efficiency than those
produced during non-bloom periods, has also been shown
in the work of Nelson et al. [19]. Such a conclusion
favours Margalef’s idea which maintains that the high
inputs of energy followed by a gradual decay of that same
energy create discontinuity, and allow life to make history which becomes recorded in the sediments [16]. In
the same way it contradicts the inference of Sancetta
[23], who, based on the study of trap material and top
box-cores material from British Columbian Fjords, considers that homogenisation by the geologic processes,
which act within the sediment mixed zone (such as bioturbation and erosion), obscures the original biologic spatial variability.
portions” of production generated by the occurrence of
upwelling. Therefore, one can assume that the taxa produced during this highly productive but relatively short
time interval are the ones that dominate the fossil record.
However, it is also well known that the sediment record is
incomplete, lacking many of the diatom species present
in the water column. The relatively extensive water column data, now available for this region of strong seasonal
variation in productivity, appears to be an excellent
opportunity to assessthe relative importance of the different seasons/species to the sedimentary record, and to
check the interpretations put forward by Abrantes [ 11.
5.2. Diatom Assemblages - Water Column versus !3ediments
Clear differences and similarities are evident from the
comparison of the most important water column taxa in
both seasons and the taxa found in the sediments. The
differences are the absence in the sediments of one of the
most abundant summer genus, Pseudo-nitzschiu, and the
persistent presence in the sediments of Paralia sulcuta, a
Diatom abundances in the sediments of the Portuguese
margin are thus confirmed as reflecting the original “pro77
F. ABRANTES,
M.T.
MOITA
species present in the plankton of both seasons but in
small numbers and mainly at the more coastal stations
(1171; Jigure 6). The similarities are the co-occurrence
and high abundances both in the water column and the
sediments of the genus Chaetoceros and Thalassiosira,
and the persistent presence of T nitzschioides (figure 6).
reported in other upwelling zones but is also found in
other areas of fertilisation and flow [5, 15]. According to
Margalef 1151, in an upwelling system this genus is represented by different species, with the mucilage producing species related to the place and intensity of
upwelling, while cells of Thalassiosira devoid of mucilage become more frequent away from the upwelling centres. Off Portugal, the genus is present in the water
column with maxima of the same order of magnitude in
both winter and summer conditions. Its distribution in the
two seasons is, however, quite different. In summer maximum abundances occur at the upwelling centres associated with chl-a and diatoms maxima Fgures 6d, 2c. 3a).
In winter, maximum abundances occur off the Tagus and
Sado estuaries and north of Nazare, within the low salinity area clearly visible in the salinity distribution
(figures 6e, 76). A pattern probably related to the
increased fertilisation generated by the higher river runoff
and nutrient input that is hkely to occur in those areas
[ 1, lo]. Thalassiosiru was, in both seasons, mainly represented by the species 7: anguste-lineata (A. Schmi.)
Fryxell and Hasle and 7: eccentrica (Ehr.) Cleve, non
mucilage producers, which together reached 60 to 100 %
of the total of Thulassiosira.
Can we explain these differences and similarities?
The summer dominant genus Pseudo-nitzschia is a genus
characteristic of the upwelling centres where primary production is maximal [5,6, 14, 15,20,24]. Pseudo-nitzschia
species are, however, small and lightly silicified, and
therefore very prone to dissolution and rarely preserved in
the sediment record [ 14, 23, 241. On the contrary, Paruliu
sulcata is a fairly rare species in the plankton, but often
reported as important in the sediments. This dense taxon
is also reported to increase in relative abundance at the
deepest traps of the British Columbia Fjords [23]. This
increase is attributed to lateral advection from shallower
sites, which can also be invoked to explain the sedimentary record reported here, given the persistent presence of
the species in the innermost part of the Portuguese shelf
(figures 6j, k). Nevertheless the coastal presence of the
species, a situation also recorded along the NW African
coast, the species is known to extend its domain over the
shelf during periods of strong upwelling [S, 61. This fact,
concurrently with the inverse relationship observed in the
Portuguese margin sediments between this species size
and the upwelling intensity (figure 6d in [l]), points to
upwelling as a determining factor for its presence
throughout the shelf sediments, a factor certainly
enhanced by the robustness of the species.
The distribution of Thalassiosira spp. in the sediments
shows a clear N/S contrast with a higher abundance (3050 %), especially of very small forms north of Nazare
@gure 68. The species present are: 7: binata Fryxell,
7: decipiens (Grunow ex Van Heurck) Jorgensen, T. delicutulu (Ostenfeld) Hasle and 7: dyporocyclus Hasle,
forms not identified in the biological samples, certainly
due to their small size and non-existence of SEM observations. Regions of high abundance are also noticeable
off the Algarve coast, where the most abundant form is
7: eccentrica.
The second most important genus in the summer water
column is Chaetoceros, the genus which also dominates
the sediment assemblage (figures 6u, c). The species of
this genus are, like Pseudo-nitzschia, fragile forms, however the genus is characterized by its ability to form resting spores when nutrients are nearly exhausted in the
euphotic zone [5, 6, 151. According to Smith et al. [26]
and Pitcher [21], diatom spores form a major component
of phytoplankton settling from the upper mixed layer.
The fact that Chaetoceros is one of the dominant diatoms
during upwelling events, associated with its ability to
form spores, may well increase its chances of becoming
incorporated in the sedimentary record of coastal
upwelling areas, such as Portugal, SW Africa and California [ 1, 24, 251.
Given that the genus Thalussiosira is common in the area
and represented by the same species in both seasons, neither the genus nor any of the species can be a reliable
indicator of a single process. However, the similarity
observed between the non-upwelling water column and
sediments distribution (figures 6e, fi points to continuous
(all year long) production conditions/nutrient input, as
the determining factor of this genus sedimentary record.
Another species, which is present at the same level of
abundance in both sampled seasons, is Thulassionemu
nitzschioides. This species is a diatom common in and
around upwelling centres [ 12, 1.51, which seems to
increase in importance during periods of long and weak
upwelling [5]. Off Portugal @gures 6g, h), although a
Thalassiosiru represents another major contributor to the
diatom assemblage in summer. A genus which has been
78
SEDIMENT RECORD OF UPWELLINGS
ides, while in winter Thalassiosira and Thalassionema
nitzschioides are the most important taxa. In the sediments, Chaetoceros dominance appears to reflect the
importance of the short but high production associated
with upwelling, while Thalassiosira appears to mark
more persistent fertility conditions, which are likely to
occur in the northern area.
secondary form during upwelling, the species is present
in the upwelling centres. In winter, its level of abundance
(lo3 cells/L) is the same as during summer, and it has
an homogeneous distribution all along the shelf. This
situation seems to be reflected in the low numbers and
homogeneous distribution found in the western shelf
sedimentary cover.
Aside from the disparity between biological and geological scales used in this study, the recurrence of the
upwelling phenomena on the Portuguese margin was
shown to leave a clear imprint in the sediments, where the
original hydrological and biological variability is actually
preserved. Even though some plankton species, such as
Pseudo-nitzschia, never make it to the sediments, this
does not appear impeditive of correct paleoecological
inferences from the coastal upwelling sedimentary
record. In fact, the dominant taxa of each season were
also shown to be dominant in the sediments, and to have
distribution patterns similar to their plankton distribution.
6. CONCLUSIONS
Upwelling determines the production patterns observed
off Portugal. At the temperature defined upwelling centres, phytoplankton biomass at the surface is ten times
higher during an upwelling situation than during a nonupwelling period. Diatoms are the major phytoplankton
group during upwelling, while coccolitophorids dominate
during winter.
The comparison of the total phytoplankton biomass, diatoms and coccolitophorids abundance (# cells/L and %
abundance) distribution in the water column, during a
non-upwelling and an upwelling situation, and the same
groups’ distribution in the sediments reveals total diatom
distribution pattern in the sediments as a clear record of
the diatom dominance of the phytoplankton during
upwelling. The same is true for the coccolithophorids,
even though it is clearly more important in winter phytoplankton. The distribution of this group in the sediments also shows a visible connection to the distribution
of the same group during upwelling periods.
Acknowledgements
This work was supported by JNICT ICDE contract
no 572.83.92, the Tnstituto Geologic0 e Mineiro and Instituto de Investigacao das Pescas e do Mar. The authors
wish to thank the phytoplankton and marine geology laboratory technicians for their support with sample preparation. Thanks are also due to the masters and crews of
research vessels Almeida Carvalho and Noruega for their
efficient help at sea. Criticism by two anonymous reviewers contributed to improving this paper.
Water column diatom assemblages during upwelling are
mainly composed of Pseudo-nitzschia and Chaetoceros
followed by Thalassiosira and Thalassionema nitzschio-
REFERENCES
[l] Abrantes F., Diatom assemblages as upwelling indicators in
surface sediments off Portugal, Mar. Geol. 85 (1988a) 15-39.
[2] Abrantes F., Diatom productivity peak and increased circulation during latest Quatemary deglaciation: Western Mediterranean, Mar. Micropaleontol. 13 (1988b) 7696.
[3] Barnola J.M., Raynaud D., Korotkevich Y.S., Lorius C., Vostok ice core provides 160,000-year record of atmospheric CO*,
Nature 329 (1987) 408-414.
[4] Berger W.H., Global Maps of Ocean Productivity, in: Pruductivity of the Ocean: Present and Past., Berger W.H., Smetacek
V.S., Wefer G., (Eds), John Wiley and Sons, New York, 1989,
[5] Blasco, D., Estrada M., Jones B., Short time variability of phytoplankton populations in upwelling regions - The example of
Northwest Africa, Proceedings of the International Symposium on Coastal Upwelling, Los Angeles (1981) 339-347.
[6] Blasco D., Estrada M., Jones B., Relationship between the
phytoplankton distribution and composition and the hydrography in the northwest African upwelling region near Cabo Corbeiro, Deep-Sea Res. 27 A (1980) 799-821.
[7] Boltovskoy D., Alder V., Abelman A., Radiolarian Sedimentary Imprint in Atlantic Equatorial Sediments: Comparison
with the Early Flux at 853 m, Mar. Micropaleontol. 23 (1993)
1-12.
429455.
79
F. ABRANTES,
M.T. MOITA
[8] Estrada M., Blasco D., Two phases of the phytoplankton community in the Baja California upwelling. Limnol. Oceanogr.
24 (1979) 1065-1080.
[9] Fiuza A., Upwelling patterns off Portugal. in: Coastal
Upwelling its sediment record., Stress E., Thiede J.. (Eds.) Plenum, New York, 1983, 85-98.
[IO] Fiuza A., Hidrologia e Dinamica das Aguas Costeiras de Portugal, Universidade de Lisboa (1984).
[ 1I] Filiza A., Macedo M.E., Climatological space and time variation of the Portuguese coastal upwelling, Oceanol. Acta 5
(1982) 31-40.
[12] Hasle G.R., Mendiola B.R., The Fine Structure of Some 7&llassionema and T’alnssiothrix Species, Phycologia 6 (I 967)
107-125.
[ 131 Hutchings L., Pitcher G., Probyn T., Bailey G., The Chemical
and Biological Consequences of Coastal Upwelling, Proceedings of the Upwelling in the Ocean. Modern Processes and
Ancient Records, Berlin, 1994, 65-83.
[14] Lange C.B., Treppke U.F., Fisher G., Seasonal diatom fluxes
in the Guinea Basin and their relationships to trade winds,
hydrography and upwelling events, Deep-Sea Res. 4 I (I 994)
859-878.
[ 151 Margalef R., Phytoplankton communities in upwelling areas,
The example of NW Africa, Oecol. Aquat. 3 (1978) 97-132.
[16] Margalef R., Asimetrfas introducidas por la operation de la
energfa externa en secuencias de sedimentos y de poblaciones.
Acta Geologica Hispanica 16 (198 I) 35-38.
[ 171 Moita T., Spatial Variability of Phytoplankton Communities in
the Upwelling Region off Portugal, Proceedings of the Jntemational Council for the Exploration of the Sea, L64 (1993) I 20.
[18] Monteiro J.H., Dias J.A., Gaspar L., Possolo A., Recent
marine sediments of the Portuguese continental shelf, Proceedings of the Present Problems of Oceanography in Portugal
(I 980) Lisbon.
] 191 Nelson D.. Treguer P., Brzezinski M., Leynaert A.. Queguincr
B., Production and dissolution of hiogenic silica in the ocean:
Revised global estimates. comparison with regional data and
relationship to biogenic sedimentation, Global Biogeochemcal Cycle 9 (1995) 359-372.
1201 Olivieri E., A Description of the Hydrography and Phytoplankton Communities in the LIpwelled Waters of the Cape Peninsula, South Africa, September 1972-February 1973, S. Afr. J.
mar. Sci. 1 (1983) 199-220.
[2l] Pitcher G.. Phytoplankton seed populations of the Cape Peninsula upwelling plume, with particular reference tu resting spores of Chaetoceros (Bacillariophyceae)
and their role in
seeding upwelling waters. Est. Coast. Shelf Sci. 31 (1990)
283-301.
1221 Rios AX, Perez EE, Fraga F., Water masses in the upper and
middle North Atlantic Ocean east of the Azores, Deep-Sea
Res. 39 (1992) 645-658.
1231 Sancetta C., Processes controlling the accumulation of diatoms
in sediments: a model derived from british Columbian Fjords,
Paleoceanography 4 ( 1989) 235-25 I.
1241 Sancetta C., Diatoms in the Gulf of California: Seasonal flux
patterns and the sediment record for the last 15,000 years.
Paleoceanography 10 (1995) 67-84.
1251 Schuette C.. Recent marine diatom taphocoenoses off Peru and
off Southwest Africa. Reflection of coastal upwelling, Oregon
State LJniversity (1980).
[26] Smith W., Heburn G., Barber R., O’Brien J., Regulation of
phytoplankton communities by physical processes in upwelling ecosystems. J. Mar. Res. 41 (1983) 539-556.
[27] Sousa E, Bricaud A., Satellite-derived phytoplankton pigment
structures in the Portuguese upwelling area, J. Geophys. Res.
97 (1992) 11.343-I 1,356.
[28] Wefer G., Fisher G., Seasonal Patterns of Vertical Flux in
Equatorial and Coastal Upwelling Areas of the Eastern Atlantic, Deep-Sea Res. 40 (1993) 1613-1645.
80
SEDIMENT RECORD OF UPWELLINGS
Appendix la. CICLOS I (August, 1985).
SeaIons stations
s II
SN
sv
s VI
s VIII
s XII
s XIII
sxv
s XVI
s XVIII
8
9
10
11
12
20
21
22
23
24
25
26
27
28
29
30
31
32
34
35
36
37
38
39
41
48
49
50
51
52
70
71
72
73
14
15
76
77
78
79
86
87
88
89
90
92
93
94
95
96
97
Let.
N
Long.
fW
41”25’
41”25’
41”25’
41”25’
41”25’
40”30’
40030’
40”30’
40”30’
40”30’
40”30’
KY05 ’
4o”OS’
40”05’
40”05’
4O”OS’
40”05 ’
8”49’
8”58’
9”OS’
9Y2.5’
9017’
8”50’
9”Ol’
9”11.5’
9”21’
9”30’
9”37’
9O48.5’
9”40’
9”34’
9”25’
9”15.5’
9w6.5
40”05’
39040’
39”4il’
39W’
39039.5’
39”40’
39”40’
38”55’
8”58’
9”M’
9015’
9”25’
9”33’
9”39’
9047’
9”21.5’
9”37’
9”48’
38”55’
38”55’
38”55’
IO”04
38”55’
38”W
38”W’
38”CQ’
38°K”
38”W
31035,
37”35’
37”35’
37”35’
31”35’
36”40’
36”47’
36Y4.5’
36O57.5’
37”W
37005.5’
37”rH’
36”54’
36O51.5’
36’45’
36”39’
lO”21’
8O52.5’
8”58’
9”05’
9013’
9”24’
9”29’
9”15’
9”06’
8”58’
8”50’
9”24’
9”lS’
9”06’
9003 ’
9”rKl’
8”35’
8”35’
8”35’
8”35’
8”35’
8”35’
36O58.5’
36”56’
36”50’
36’45’
36”39’
7Y.5
l”25’
I”25 ’
7”25’
7”25’
Depth
Cm)
Dist.offsh.
(Km)
35
71
loo
200
2.8
15.3
25.0
35.4
41.7
2.8
18.3
33.1
46.5
59.2
69.0
80. I
68.0
59.5
46.8
33.3
20.6
717,950
51,840
28,180
1,860
1,860
532,310
29,960
6,060
2,256
780
1,140
1,200
8,40
450
1,320
4,900
9,940
94.3
88.9
68.8
9.2
10.1
90.1
70.1
20.7
21.0
13.4
1.9
4.1
58.3
8.4
10.0
20.5
24.8
20
6,040
6,180
9.150
40
3,100
6,060
96
180
39.270
12,000
0
3,000
10,824
60
7,040
0.0
0.0
14.7
30.4
49.7
0.0
1.2
20.7
0.9
3.1
66.6
41.3
0.0
56.2
81.7
0.3
17.6
23
20
125
141
180
> 1000
> ICQO
42
115
120
200
8.5
4.3
17.1
31.4
42.8
51.3
62.1
2.2
15.9
31.7
em
54,920
2,520
625
810
120
120
6,580
57.9
52.8
10.9
3.3
1.9
0.7
0.6
11.9
10.9
I .9
1.0
1,MJo
21,000
6,000
15,000
27,000
6,ooO
7,500
13,000
27,COO
6,600
12,wo
0.7
20.2
25.9
78.6
63.4
35.3
36.0
23.5
75.1
93.5
51.1
>iooo
79.3
30
0.1
19,500
62. I
34
129
289
525
ZloM)
950
566
300
142
52
> 1000
2.2
10.2
20.4
32.1
48.2
58.7
38.2
25.0
13.2
1.5
53.5
50,790
2,213
30
180
180
1,770
1,830
420
1,863
810
550
92
34
26
52
98
205
741
> 1000
34.8
15.6
8.7
3.0
1.5
9.3
20.4
26.9
38.9
50.0
15,690
25,170
10,200
25,680
190,640
195,760
51,020
35,100
64,380
118,950
9,210
2,970
43.9
3.8
0.1
0.7
1.1
10.7
1.9
0.9
3.1
14.5
47.4
16.0
28.7
80.7
83.4
30.1
58.0
64.3
59.1
31.1
8.2
21,440
15.875
22,890
15,210
6,540
8,340
53,550
43,740
31,374
42,340
11,730
28,410
36,600
34,100
32,320
24,440
8,660
18,200
37,590
12,390
29,760
18.5
27.4
86.7
60.9
39.5
50.6
54.9
96.7
52.2
39.2
22. I
44.5
40.9
14.4
13.8
14.4
14.3
18.2
18.7
41.8
82.2
1,020
600
3,180
103,580
82,780
4,060
5,140
24,760
56,430
2,940
240
100
200
497
530
535
23.2
29.6
40.8
50.0
61.1
5,240
3,330
120
240
300
13.0
6.0
0.5
0.9
I.1
16,600
39,720
8,430
7,560
14,430
41.1
71.3
35.0
27.0
54.5
0
30
0
0
fxl
> 1000
16
68
107
128
213
971
> 1000
510
198
135
101
77
54.8
Ditoms Diatoms Comdtth. CoccoIith.
(II” cellsA) (C)
(0’ cells/l)
(%)
3,920
132
240
0
Psetinihschia
(n” cells/l)
631,150
25,540
23.300
90
540
13,000
5,380
780
72
30
60
0
120
60
144
1,880
3,040
14,.040
160
216
0
60
0
30
60
60
0
0
0
5,180
275
0
0
0
0
0
0
108
1,140
Chaetocems Thalas~iusitaspp.
(n” cekil)
(n” cellr/l)
61,320
420
15,760
300
0
60
6,640
620
360
216
0
0
0
240
0
48
0
500
160
IM)
60
60
37,120
3.400
0
0
90
0
0
1,640
1,240
0
90
6,640
660
520
12
30
30
0
0
0
48
440
240
1,540
180
48
0
60
0
30
520
3M)
0
0
I &.whkhh
(n” ceII.4)
f! s&a&
(n” cellSn)
680
1,940
1.100
420
240
11,220
40
0
96
0
0
0
0
660
0
0
60
760
2,%0
2,640
888
Soil
90
60
0
100
0
0
0
0
0
0
33,720
150
0
0
0
0
0
0
0
5,280
M)
60
300
8,640
9,620
l,N
225
0
0
30
3,280
1,530
270
60
340
15
0
0
0
0
0
30
0
220
0
120
120
220
220
0
0
0
60
0
0
loo
210
0
0
0
0
0
0
0
0
1,o‘UJ
4,780
6,020
1,530
30
180
0
120
210
21
5,770
210
30
180
8,660
14,340
440
mQ
180
0
270
0
60
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
20
0
0
0
0
0
0
0
0
20
0
0
0
0
0
0
0
0
0
0
0
104
105
106
107
108
109
81
120
270
0
0
0
680
0
0
0
0
F. ABRANTES,
M.T. MOITA
Appendix lb. CICLOS III (January. 1986).
Lat.
(NJ
Long.
(W)
Depth
hn)
9
IO
II
I?
20
21
22
23
24
25
26
27
28
29
41025’
41’25’
41”25’
41025’
41”25’
40”30’
40”30’
40”30’
40”30’
40”29.8’
40”30’
Q”05’
40”05’
40”05’
40”05
8”49’
8”58’
9W.5’
9”1?
9”17’
33
75
100
200
1000
2.8
15.3
24.3
34.7
41.7
40”05 ’
40”05 ’
4o”OS’
39040’
3Yw.l’
39”40’
39”40’
39’40’
39”40’
38”55’
38”55’
38”55’
38”55’
38055’
38”55’
37”56’
37”56’
37”56’
37”56’
37”56’
37”34’
37034’
37”34’
37034’
37”34’
36”40’
23
61
100
126
195
1000
1000
470
200
132
104
75
28
32
123
2.8
18.3
33. I
30
31
32
34
35
36
37
38
39
47
48
49
50
51
52
70
71
72
73
74
75
76
77
78
79
86
8”50’
9”Ol’
901 1.5’
9”21’
9O29.7’
9”37’
Y”48.6’
9040’
9”34.5’
9”25’
9Ol5.5’
Y”c6.5’
8”58’
9”06’
9015’
87
88
89
90
92
93
94
95
96
97
104
105
106
107
I08
109
36O47.5’
36O54.5’
36O57.5’
37”W
37OO5.5’
37”W
36”54’
36”Sl .S’
36”45’
36”39’
37006’
36O58.5’
36’56’
36”50’
36”45’
36”39’
Sections Stations
s 11
s IV
SV
s VI
s VIII
s XII
s XIII
sxv
s XVI
s XVIII
8
9025’
140
9033’
170
9O38.7’
1000
9947’
> IIXIO
9027.5’
36
9037’
117
9”48’
131
I O”O&
190
IO”21
527
IO~21’
1000
g”54.5’
75
9wl’
135
290
9007’
54s
9”16’
1000
9”26’
9025’
1000
656
9”17’
9”08’
342
9”W
160
x050
55
1000
9”24’
Y”l5’
9”06’
9”03’
770
527
50
9”W
so35
40
31
53
lo0
210
700
1000
20
loo
220
490
550
528
8”35’
R”35’
8035’
8”35’
8”35’
7”25 ’
7025‘
7”25’
7025’
7”25‘
7025’
Dist offsh. Diatoms Diatoms Caccalith. Coecolith.
(Km)
(n” cells/I)
(%)
(n” cells/I)
(%)
46.5
58.8
69.0
80.2
68.0
60.3
46.8
33.3
20.6
8.5
4.3
17.1
31.4
42.8
50.9
62.7
2.2
15.9
31.7
54.8
63.4
79.3
9.5
17.5
27.8
40.9
55.5
52.9
41.1
27.9
16.2
1.5
53.5
34.2
15.6
8.7
.o
1.5
9.3
20.4
26.9
38.9
50.0
9.3
23.2
29.6
40.8
50.0
61.1
6.170
6,240
3,840
1,050
540
980
42.800
4,660
336
1,890
300
420
705
17.790
432
620
1,300
17.920
470
820
515
7.020
17,010
2,010
620
220
420
270
3,360
1.020
3.100
3.050
3,810
10,350
I.920
510
I.080
2,610
5,325
4.340
90
360
330
630
I .%O
980
2,540
700
540
140
570
940
540
2.520
I.140
1,560
510
18.2
48.4
37.6
4.4
6.7
7.120
s.320
5,420
16.500
6.750
Il.7
73.00
17.9
2.4
41.7
I.1
OS
5.3
36.4
4.0
8.5
12.3
17.4
7.0
13.0
5.MO
15,020
5.060
12,(K)O
2.010
9.900
2 I 090
12,480
26,100
9,600
6. I20
9, I20
36.640
6,020
5,140
I.8
22.6
31.6
9.5
4.1
1.7
5.3
I .7
11.7
9.7
17.1
Il.7
7.8
14.2
5.2
2.2
4.4
18.8
17.6
19.8
0.5
10,200
I Y,590
22.770
13.470
9.060
4.400
7.160
15,450
13.890
7.710
I3.500
21.300
23,130
46.770
32,880
21.330
22.230
5,160
2 I .060
17,220
16,650
32.6
63.0
42.3
63.9
59.8
34.4
90.2
94.8
48.4
73,0
74.7
I.8
1.7
3.4
9.4
7.7
II.7
3.3
?.I
I.1
2.8
2.8
I .3
2.8
4.3
6.7
18.870
16,950
16,100
15.080
I I.320
17.660
20.100
18.600
8,460
12,870
19.220
27.520
33,630
25.080
20.670
1.Y
25.590
93.2
87.5
86.9
72.4
89.0
81.2
Y5.0
73.2
67.7
62.9
57.3
69.2
37.8
94. I
89.0
96.9
82
21.0
II.?
s.1.I
69. I
83.3
60. I
25.6
19.4
85.0
44.4
37.8
26. I
92.3
5?.4
89.9
84.3
86.5
35.6
89.7
81.3
81.8
47.2
64.1
89.5
94.0
91.1
31.2
69.5
78.7
98.1
Weudonifz~chia
(n” cells/l)
Chueroceros
(n” cells4)
.___~.
Thuhsiosim spp. I: ni&whioides I! sulcatrr
(n’ cells/l)
In” cells/l1 (n” cells/l)
(I
0
0
3UJ
0
IO
0
0
0
n
.X660
5.IMi
!.210
INI
4s
x0
760
241
50
!(I
0
100
60
0
90
0
150
0
150
0
0
0
0
260
40
0
0
0
0
I50
I x0
37,7Ml
2.640
I44
Yil
90
0
120
12.780
216
I40
20
80
30
20
I?iI
IJ
I.220
4x
780
120
0
180
570
38
26U
360
4,640
100
40
50
5.610
15.150
2 IO
(1
250
210
990
360
120
44
80
240
0
320
7i
-.
Ml
I 50
I80
0
0
0
0
60
90
I60
0
0
0
60
I 20
0
0
150
2(K)
0
210
30
n
0
40
0
0
0
0
90
0
0
30
30
510
30
1,350
0
(I
0
7.280
0
0
0
150
30
60
0
0
0
0
3.OMl
0
380
600
660
2,880
90
@.I
I 20
540
570
420
0
0
30
60
140
40
I 80
0
0
0
0
40
0
750
180
0
90
0
0
0
30
0
I40
I50
60
450
I 20
0
210
120
510
340
0
30
Ml
20
20
0
40
0
30
0
0
80
20
0
30
30
30
0
60
I50
460
300
330
540
0
I20
60
120
300
204
0
0
60
80
200
160
500
0
60
0
0
I20
40
I20
0
0
90
30
(1
il
0
0
540
0
300
0
0
0
(I
0
0
0
0
460
1040
210
40
0
0
0
0
240
8X
2ul
0
0
0
0
0
0
0
0
0
0
0
0
I 80
0
0
0
80
0
380
0
180
210
0
90
300
0
64
0
0
0
SEDIMENT RECORD OF UPWELLINGS
Appendix lc. Sediments.
Lat.
(N)
Spmpk
number
116
120
122
123
124
I65
167
168
170
172
174
696
698
700
702
703
704
706
708
709
215
217
218
219
221
224
226
242
244
246
248
249
252
254
256
449
451
453
455
457
458
445
426
415
386
387
388
389
393
395
397
362
366
369
371
338
41
41
41
41
41
40
40
40
40
40
40
40
40
60
40
40
40
40
40
40
39
39
39
39
39
39
39
39
39
39
39
39
39
39
39
38
38
38
38
38
38
37
38
37
37
37
37
37
37
37
37
37
36
36
36
37
35.00
34.90
35.w
35.u)
34.50
48.50
48.60
48.50
48.50
48.50
48.50
II.50
I1.50
Il.50
12.30
12.20
11.70
11.30
II.10
8.60
43.10
43.20
43.00
43.10
43.00
43.00
42.90
5.20
5.00
5.00
5.00
5.00
5.00
5.00
5.10
12.30
13.10
13.90
14.40
14.80
15.00
48.80
5.00
55.00
34.90
34.80
34.90
35.10
35.10
34.90
35.00
0.60
58.20
55.00
53.00
3.50
Long.
W)
8
9
9
9
9
9
9
9
8
8
8
9
9
9
9
9
9
8
8
8
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
8
8
8
8
8
9
8
8
8
8
8
8
8
9
9
8
8
9
9
8
52.30
0.90
5.90
9.80
11.50
12.20
4.90
1.40
55.50
48.90
43.90
35.80
31.60
24.20
11.30
6.50
3.90
59.30
56.00
53.40
4.20
8.00
10.70
13.60
20.00
25.50
30.00
26.70
31.70
34.90
39.90
42.00
46.00
50.00
56.50
2.10
58.10
54.50
52.10
50.00
48.50
11.80
53.90
56.50
52.00
52.90
54.00
55.00
59.00
1.10
3.20
58.00
59.00
2.70
3.80
40.00
Depth
(m)
40
85
100
100
105
140
95
85
50
35
10
220
IS8
135
IO0
85
65
45
I8
IO
20
53
70
100
130
I30
I45
30
52
62
94
94
II6
I44
154
160
140
120
105
60
35
450
112
105
95
II0
II8
129
160
190
245
17
80
93
I57
33
36
Dist.
(Km)
0.6
1.7
2.5
3.0
3.3
4.2
3.2
2.7
1.8
0.9
0.3
6.0
5.3
4.2
2.5
I.8
1.4
0.7
0.3
0.2
0.1
0.7
I.1
I.5
2.4
3.1
3.8
0.3
1.0
1.5
2.2
2.5
3.1
3.6
4.5
2.2
1.9
1.4
I.0
0.7
0.3
10.0
0.7
I.2
0.6
0.8
0.9
1.0
1.6
2.0
2.3
0.1
0.9
1.5
1.9
0.3
0.4
TLm/ec
(‘103)
4778
4160
100
1100
174
543
1030
2500
19500
6000
500
60
63
113
950
3797
3100
loo0
zoo0
IO27
529
600
941
794
162
I75
211
950
1600
MO
391
600
678
138
214
300
180
333
278
1400
30500
851
221
MO
200
300
958
II44
125
250
307
1000
80
700
67
200
1064
83
coceolitbs
(%)
Chaetoceros
resting spores
(%)
13
10
IO
IO
IO
I
I5
20
7
5
3
50
45
15
2
P
I
10
20
I5
2s
10
I
10
20
2s
30
30
30
40
50
10
30
2s
35
2s
30
50
50
45
37
50
P
35
P
45
2s
30
li Solc&
@)
l%aheiom
(%)
T. nirzrckioidee
(96)
33
61
9
57
44
25
7
69
75
39
15
22
8
11
I8
37
34
52
10
IO
31
56
31
I9
12
I6
IS
I9
8
I3
II
9
6
0
I
0
0
0
0
0
0
0
0
0
4
6
8
28
23
4
4
24
I3
26
28
I5
4
7
4
2
0
59
7
4
3
79
31
39
42
54
34
26
29
58
I7
4s
52
48
50
41
58
54
45
68
28
57
71
58
IO
22
29
I9
20
20
25
22
12
13
6
4
7
I4
19
11
8
II
0
I
7
I
4
3
7
0
I
0
I
2
0
0
I
0
0
I
0
0
0
0
0
0
0
0
0
0
0
0
3
3
1
1
0
I
4
6
40
28
71
75
38
16
36
30
31
30
II
I
26
42
40
27
30
13
8
28
40
30
3
IO
8
5
2
4
2
5
2
3
I
3
6
5
9
2
0
0
0
0
0
0
0
0
2
0
2
0
I
I
0
52
I
I1
6
44
50
2
F. ABRANTES,
M.T. MOITA
--
---
--____.-
Appendix lc. Sediments (suitel.
Sample
number
Lat.
(N
LOI&.
ml
341
333
345
31
31
36
I.60
0.00
58. IO
347
349
3s I
273
275
276
217
278
280
282
281
317
326
1316
1318
1324
36
36
35
37
37
37
31
31
36
36
36
36
36
41
42
40
56.00
53.80
I325
I326
1327
1331
1333
I335
I337
1338
I339
I340
1341
I343
1344
I348
1354
40
40
40
39
39
37
37
37
37
37
43.41
41.30
34.43
54.80
53.00
22.08
12.50
14.15
15.44
17.08
IO
IO
IO
9
IO
IO
9
9
9
9
36
36
36
36
36
43.63
50.00
43.70
41.10
53.37
9
9
9
8
1
I355
1356
1358
1360
1361
I362
1363
1365
I366
I367
1368
I369
I370
1371
I373
I374
1377
36
36
36
36
36
36
36
36
36
36
36
36
36
36
36
36
37
52.17
SO.00
37.28
40.12
44.50
47.50
51.00
53.70
46.31
45.20
41.10
37.80
44.14
43.92
34.59
41.70
18.00
7
7
7
7
7
7
7
7
8
7
7
7
8
8
8
8
9
52.50
8.50
6.00
3.90
2.30
2.20
57.00
54.60
54.50
50.30
53.40
44.41
14.34
56.85
8
8
8
8
8
8
7
7
7
7
7
7
7
7
8
8
I2
9
9
Depth
Cm)
Dist.
(Km)
40.00
40.00
40.00
38
63
80
0.7
l.lJ
1.4
40.00
40.00
40.00
30.00
30.10
30.10
30.10
30.10
29.90
30.00
48.00
10.20
52.00
24.77
40.17
34.23
98
105
II0
8
19
47
74
95
I80
405
235
95
110
5035
2080
2010
I880
3590
3380
1045
4950
4145
2507
1285
900
853
1518
787
880
720
448
502
510
850
765
645
1.7
2. I
2.4
0.3
0.8
I.2
I.4
I.8
2.4
2.8
I.1
2.8
1.8
37.9
34.4
60.3
86.2
95.0
153.5
53.4
91.0
95.0
51.7
1.85
12.20
20.54
46.60
49.00
30.23
42.70
31.01
24.03
19.97
30.12
25.1 I
12.40
55.90
30.88
30.01
30.60
39.75
49.8 I
48.60
48.80
49.00
49.20
0.86
57.20
55.80
52.70
14.54
15.28
14.00
15.40
17.60
585
619
300
735
675
725
745
710
695
1002
740
835
3Y.7
36.2
31.0
41.4
31.0
60.3
27.6
25.9
27.6
29.3
34.5
25.9
22.4
13.8
12.1
10.3
19.0
20.7
25.9
32.8
29.3
31.0
43. I
34.5
27.6
TDiaUcc
1”ltl’)
I800
IS0
63
369
II6
325
12000
67
266
IRI
286
96
139
526
II2
I50
43
I61
23
I76
I60
685
77
634
74
0
0
0
60
26
65
5Y
28
0
0
26
0
0
14
0
25s
2OR
I9
0
36
I55
0
0
0
71
0
84
Coccoliths
(8)
20
20
30
35
20
20
3
20
25
20
25
30
30
30
IS
25
-
Chaetoceros
resting spores
(Fir)
5
II
4
8
5
7
li .sulcata
(%I
-
-
L nitwftioidez
(ori
_l_l_
0
4
0
6
13
II
0
I
I
I
I
I
2
0
0
0
3
23
5
3
3
2
9
I7
45
8
15
I3
I2
8
8
I2
4
3
47
50
52
M
20
3
I
20
9
30
30
4
21
IO
7
8
72
7
7
I
8
3
53
7
7
7
36
I
3
I
4
3
7
54
42
62
45
38
41
I
Thalassiom
(76)