ISSN 00014370, Oceanology, 2014, Vol. 54, No. 5, pp. 596–605. © Pleiades Publishing, Inc., 2014.
Original Russian Text © Z.Z. Finenko, V.V. Suslin, I.V. Kovaleva, 2014, published in Okeanologiya, 2014, Vol. 54, No. 5, pp. 635–645.
MARINE BIOLOGY
Seasonal and LongTerm Dynamics of the Chlorophyll
Concentration in the Black Sea according to Satellite Observations
Z. Z. Finenkoa, V. V. Suslinb, and I. V. Kovalevaa
a
Institute of Biology of the Southern Seas, Sevastopol, Russia
b
Marine Hydrophysical Institute, Sevastopol, Russia
email: [email protected]
Received June 12, 2013; in final form, October 7, 2013
Abstract—The spatial and temporal variability of the chlorophyll (Chl) concentration in the surface water
layer of the Black Sea in 1998–2008 has been analyzed using the data obtained by the SeaWiFS satellite sen
sor. In the deepsea areas, the seasonal pattern of the Chl concentration is represented by a Ushape curve.
The maximal concentrations are observed in the winter–spring and autumn periods, while the minimal, in
the summertime. In the northwestern Black Sea, the maximal concentrations are registered in mostly the
summer and autumn periods. Pronounced interannual variability is found for the summer concentrations of
Chl observed for an 11year period. After a cold winter, the concentration of Chl in the spring period is
3⎯5 times higher compared to the mildwinter years. In December–March, a negative correlation between
the water temperature and the average Chl concentration is registered.
DOI: 10.1134/S0001437014050063
1. INTRODUCTION
2. MATERIALS AND METHODS
In the Black Sea, the observations of the Chloro
phyll “a” concentrations (Ca) were started in 1960 [4].
Since that, a huge amount of data has been collected,
which has made possible defining the variability of Ca
in different years and seasons [1, 3, 8, 9, 15]. However,
these data do not allow correctly describing the sea
sonal dynamics of the Ca. Some authors attempted to
describe the multiyear average seasonal dynamics of
Ca in the deepsea area [3, 6]. However, regard must be
paid to the fact that these values were obtained by aver
aging the disembodied data collected in different years
and seasons, and they did not take into account the
interannual variability. The high variability of Ca on
both the spatial and temporal scales demands a short
period of time, a high frequency of the observations,
and a scale of dozens and hundreds of square kilome
ters covered in order to assess the seasonal and inter
annual dynamics. The collecting of such a dataset even
onboard a research vessel is an unachievable goal.
Most of the method limitations may be skipped if Ca is
calculated using satellite observations, which have
been performed daily with a high resolution grid over
the whole sea area for a long time period.
The data of the chlorophyll concentration in the
surface water layer collected by the SeaWiFs color
scanner in 1998–2008 and stored by the Goddard
Space Center were used in the present study. The
dataset is made up of daily scans with 4 km × 4 km
resolution comprising the normalized spectral illumi
nation of the surface of the water (nLw) for the wave
lengths of 490, 510, and 555 nm after the standard
atmospheric correction and fitting specific criteria.
The dataset version is R2010.0. The calculation of the
Chl concentration was based on two indexes: I510 =
nLw(555)/nLw(510) and I490 = nLw(510)/nLw(490),
which were averaged for a twoweek period using a
grid of 0.025° geographical latitude and 0.035° geo
graphical longitude. The calculation algorithm of Ca
and the filtering criteria of nLw are described in detail
in [7]. The indexes I510 and I490 take into account the
absorption of the dissolved colored matter; they are
less sensitive to the errors of the atmospheric correc
tion and backscatter by particulate matter, and they
restore the concentration of Chl under the satellite
data with higher significance [7] compared to the
methods applied before [10, 11]. The temperature of
the surface of the water was also obtained by the
satellite observations (http://podaac.jpl.nasa.gov/sst,
1998–2000; http://oceancolor.gsfc.nasa.gov, 2000–
2008); it was correlated with the spatial and temporal
characteristics of the Chlorophyll areas obtained by
the SeaWiFS color scanner.
The statistical analysis was performed using Sigma
Plot in the ANOVA package.
The study aims to find the regularities of the sea
sonal dynamics and interannual variability of the
Chl concentration in the surface layer of the Black Sea
using the satellite data obtained by the SeaWiFS sensor
in 1998–2008.
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SEASONAL AND LONGTERM DYNAMICS OF THE CHLOROPHYLL CONCENTRATION
3. RESULTS
Spatial variability of the chlorophyll concentration.
The monthly averages of the chlorophyll concentra
tions in the surface water layer in 1998, 1999, and 2003
are presented in Fig. 1 as an example of the correspon
dence to the average, low, and high productivity of the
phytoplankton, respectively. During the studied
period, the northwestern Black Sea differed from the
other areas by higher concentrations of Ca. In the estu
arine zones, the maximal concentrations have reached
several dozens of µg per liter and have been observed in
the late spring–early summer, while the minimal, dur
ing the cold period of the year. Eastwards of the areas
affected by the riverine discharge, the concentration of
chlorophyll decreased rapidly. The enriching effect of
the river was observed only close to the coast (Fig. 1).
High variability of the Ca concentration was a feature
of the estuarine and adjacent areas; this was precondi
tioned by the shifts in the wind activity, riverine dis
charge, and incoming micronutrients. The near shore
currents and synoptical gyres affected the horizontal
distribution of the chlorophyll. The transport of the
phytoplankton along the sea coast from the Danube
Delta southwards played a significant role in the pro
ductivity of the western shelf of the Black Sea.
In the area of the Anatolia shelf, where the average
concentration of Ca was about 0.3–0.5 mg/m3,
patches of high concentrations (up to 1.2 mg/m3) have
been observed from time to time. In the summer, the
concentration of chlorophyll in this area was higher
compared to the deepsea area of the Black Sea. In the
meantime, in the northern Black Sea, the ranges of Ca
in the near shore and open waters did not differ signif
icantly. In the Main Black Sea current, during the
summer period, synoptical anticyclonic gyres and
meanders formed, and they transported the coastal
phytoplankton to the open sea, which, in turn, might
lead to local patches of shortterm phytoplankton
“blooms” in the open sea and high spatial heterogene
ity of the chlorophyll distribution. Mean values of Ca
in deepwater regions of the western and eastern parts
of the sea can differ by several times.
The margin that separated the shelf zone and the
deepsea zone shifts in regard to the synoptical activity
and changed greatly in time and space. During the
winter–spring period, the Main Black Sea current was
an effective barrier between the coastal and the open
sea waters. In the deepsea area, in cold and relatively
cold winters, an intensive phytoplankton bloom usu
ally occurred; it started as patches in the center of
cyclonal gyres. During several weeks, they expanded
and then joined into one large field covering hundreds
of square kilometers, as was observed, for example, in
March of 1998 (Fig. 1). In contrast, during the mild
winters, when the surface water temperature exceeded
8°C and the exchange between the surface and deep
sea water masses was low, the chlorophyll concentra
tion did not exceed 0.5 mg/m3. The monthly average
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coefficient of the spatial variability of Ca in the win
ter–spring period ranged from 40 to 65%, and it was
half as much in the summer.
Seasonal variability. In order to compare the sea
sonal dynamics of the chlorophyll in the surface water
layer, the sea area was divided into 11 regions; four of
them referred to the deep sea, and the other seven rep
resented the shelf areas (Fig. 2). During eleven years of
observations, the seasonal dynamics of Ca within the
calendar year exhibited similar patterns in all four
deepsea regions (Fig. 3). The maximal Ca concentra
tions (0.5–3.0 mg/m3) were usually observed during
the winter period, while the minimal, during the sum
mertime. However, only from time to time were low
Ca concentrations (less than 0.5 mg/m3) usual for the
summer period registered in the spring (table). The
intensive winter phytoplankton bloom lasted 1–
2 months. In the western and the eastern Black Sea, it
occurred nearly simultaneously, and only in 2003 was
there a significant temporal shift observed, when the
maximal Ca concentration was registered in the west
ern Black Sea in January and, in the eastern part, in
early April (Fig. 3). During the harsh winters, when
the surface water temperature did not exceed 8°C,
this promoted the density convection and micronu
trient transport from the deepsea to the euphotic
layer. During such years (1998, 2003, and 2004), the
chlorophyll concentration reached 1–3 mg/m3 and
exceeded the range observed during the mild winters
by twofold–fourfold.
In the summer, the Ca concentration in the deep
sea areas varied from 0.2 to 0.6 mg/m3. The minimal
summer concentrations were usually observed in
August, while the maximal, in the early summertime,
when the coccolithiphorid bloom occurred and the
chlorophyll concentration increased. Starting in Sep
tember, the Ca increased gradually and turned into a
winter–spring maximum (table).
The seasonal cycle of chlorophyll was characterized
by several maxima during the year on the shelves of the
Romanian, Bulgarian, and Ukrainian coasts, while the
peak was observed in the summertime (Fig. 4). The
duration of the summer peak of the phytoplankton
bloom varied from 2 to 3 months. The autumn and win
ter phytoplankton blooms were shorter and less pro
nounced. Generally, high annual variability of Ca was a
characteristic of the areas belonging to the northwestern
shelf.
Along the Anatolia shelf, the seasonal cycle was
characterized by the winter bloom (December–Febru
ary) lasting one to two months. In 2000, 2003, and
2004, the maximal Ca concentration was 3 mg/m3, but,
during the other years, it did not exceed 1.5 mg/m3. We
suppose that the water circulation caused by the synop
tical processes affects the interannual variability of the
Ca concentration greatly during the cold season of the
year. In the summertime, the average Ca concentration
was 0.25–0.35 mg/m3 and it fell within the range
observed in the adjacent opensea areas.
598
FINENKO et al.
January 1998
February 1998
March 1998
April 1998
January 1999
0.1
0.3
0.7
1.5
April 1999
3
10
Fig. 1. Spatial and temporal distribution of the Chl concentration in the surface layer of the Black Sea in 1998, 1999, and 2003.
Minimal Ca values in comparison to other regions
of the Black Sea shelf have been recorded along the
Caucuses and Crimean coasts. In winter, they were
mainly <1.0 mg/m3 and only in 2000 and 2003 did they
reach 2.0 mg/m3; in summer, 0.2–0.3 mg/m3.
Therefore, these results allow us to describe the
seasonal and interannual dynamics of the Ca concen
tration in detail for all the areas of the Black Sea. In the
deepsea part, the seasonal dynamics of the chloro
phyll concentration can be expressed as a Ushape
curve, while following the same trend each year. The
intensive phytoplankton bloom that occurs in the win
ter and spring is characterized by a higher chlorophyll
concentration in comparison to the summer period
(table). The seasonal dynamics of the Ca in the deep
sea areas of the Black Sea differ from the other seas
and the open ocean located in the temperate climatic
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May 1999
June 1999
January 2003
February 2003
March 2003
0.1
0.3
0.7
1.5
April 2003
3
599
10
Fig. 1. (Contd.)
zone. These differences are preconditioned by the
depth of the picnocline located in the Black Sea at a
lower depth than in the other areas.
On the northwestern shelf of the Black Sea affected
by the riverine discharge, several chlorophyll maxima
are observed within a year. Opposite to in the deepsea
areas, they are registered in the summer–autumn
period.
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Interannual variability of the chlorophyll concen
tration. A negative trend was found for the chloro
phyll concentration in the coastal areas of the north
western Black Sea (area nos. 4–6) during the period
of 1998–2008. The annual decline of the chlorophyll
concentration in the Dnepr River Delta area and
along the Bulgarian coast was 0.02 mg/m3, while at
the Danube River Delta area, 0.05 mg/m3 (Fig. 5). In
the deepsea areas (nos. 1–3), no significant trend
600
FINENKO et al.
4
5
11
7
2
6
1
3
8
10
9
Fig. 2. Studied areas where the comparison of the seasonal dynamics of the Chl concentration in the surface water layer was per
formed.
5
1
4
3
2
1
0
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
4
Ca, mg/m3
2
3
2
1
0
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
5
3
4
3
2
1
0
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
Fig. 3. Seasonal dynamics of the Chl concentration in the analyzed areas (1, 2, 3) located in the deepsea part of the Black Sea
(the bars indicate the standard deviation).
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SEASONAL AND LONGTERM DYNAMICS OF THE CHLOROPHYLL CONCENTRATION
Seasonal average concentrations of Chl in 1998–2008
Area 1
Winter
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
0.69 ± 0.05
0.59 ± 0.04
0.72 ± 0.11
0.64 ± 0.22
0.66 ± 0.11
1.02 ± 0.24
0.88 ± 0.17
0.95 ± 0.32
0.74 ± 0.14
0.78 ± 0.22
1.12 ± 0.21
Area 2
Winter
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
Winter
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
0.69 ± 0.15
0.51 ± 0.09
0.86 ± 0.26
0.56 ± 0.18
0.66 ± 0.15
1.32 ± 0.32
0.72 ± 0.06
0.91 ± 0.35
0.71 ± 0.10
0.71 ± 0.06
1.05 ± 0.19
Area 7
Winter
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
0.70 ± 0.18
0.64 ± 0.05
0.78 ± 0.19
0.87 ± 0.34
0.74 ± 0.10
0.90 ± 0.23
1.10 ± 0.63
1.06 ± 0.39
0.80 ± 0.19
0.95 ± 0.37
1.34 ± 0.09
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No. 5
Summer
Autumn
0.22 ± 0.03
0.23 ± 0.03
0.25 ± 0.01
0.38 ± 0.12
0.26 ± 0.04
0.31 ± 0.04
0.29 ± 0.02
0.28 ± 0.07
0.27 ± 0.05
0.4 ± 0.04
0.37 ± 0.07
0.34 ± 0.07
0.35 ± 0.11
0.37 ± 0.16
0.39 ± 0.11
0.41 ± 0.19
0.48 ± 0.13
0.49 ± 0.24
0.42 ± 0.15
0.42 ± 0.16
0.66 ± 0.28
0.82 ± 0.41
Summer
Autumn
0.20 ± 0.03
0.21 ± 0.03
0.27 ± 0.02
0.32 ± 0.07
0.22 ± 0.03
0.30 ± 0.04
0.27 ± 0.02
0.30 ± 0.04
0.26 ± 0.05
0.37 ± 0.04
0.32 ± 0.06
0.33 ± 0.08
0.35 ± 0.10
0.37 ± 0.11
0.42 ± 0.16
0.39 ± 0.20
0.46 ± 0.09
0.56 ± 0.41
0.40 ± 0.16
0.44 ± 0.16
0.61 ± 0.23
0.76 ± 0.33
Spring
Summer
Autumn
0.43±0.12
0.36±0.11
0.54±0.23
0.56±0.39
0.50±0.13
0.60±0.21
0.51±0.12
0.49±0.11
0.39±0.06
0.47±0.09
0.37±0.05
0.20 ± 0.03
0.26 ± 0.09
0.23 ± 0.02
0.29 ± 0.10
0.23 ± 0.04
0.27 ± 0.01
0.25 ± 0.04
0.28 ± 0.04
0.27 ± 0.04
0.34 ± 0.04
0.33 ± 0.05
0.34 ± 0.08
0.41 ± 0.18
0.37 ± 0.13
0.48 ± 0.17
0.36 ± 0.24
0.45 ± 0.12
0.45 ± 0.26
0.42 ± 0.20
0.43 ± 0.15
0.53 ± 0.21
0.78 ± 0.35
Spring
Summer
Autumn
0.48±0.14
0.73±0.16
0.50±0.18
0.58±0.19
0.51±0.09
0.92±0.39
0.56±0.08
0.51±0.14
0.57±0.25
0.54±0.08
0.53±0.1
0.44 ± 0.19
0.48 ± 0.11
0.56 ± 0.31
0.49 ± 0.28
0.28 ± 0.11
0.34 ± 0.13
0.44 ± 0.27
0.42 ± 0.20
0.48 ± 0.26
0.38 ± 0.03
0.37 ± 0.05
0.48 ± 0.11
0.49 ± 0.10
0.45 ± 0.12
0.47 ± 0.13
0.55 ± 0.29
0.53 ± 0.26
0.53 ± 0.35
0.55 ± 0.24
0.54 ± 0.29
0.68 ± 0.29
0.95 ± 0.52
1.19 ± 0.86
0.40 ± 0.09
0.47 ± 0.09
0.39 ± 0.08
0.52 ± 0.09
1.02 ± 0.44
0.95 ± 0.44
0.51 ± 0.10
0.45 ± 0.09
0.57 ± 0.14
0.51 ± 0.05
Spring
0.72 ± 0.06
0.52 ± 0.07
0.79 ± 0.15
0.62 ± 0.17
0.66 ± 0.07
1.19 ± 0.25
0.88 ± 0.14
0.93 ± 0.44
0.72 ± 0.11
0.73 ± 0.07
0.97 ± 0.03
Area 3
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Spring
2014
0.81 ± 0.45
0.39 ± 0.08
0.51 ± 0.10
0.38 ± 0.07
0.52 ± 0.12
0.89 ± 0.33
0.68 ± 0.25
0.51 ± 0.10
0.43 ± 0.08
0.63 ± 0.19
0.52 ± 0.08
601
602
FINENKO et al.
9
8
7
6
5
4
3
2
1
0
6
Ca, mg/m3
5
5
6
4
3
2
1
0
3
7
2
1
0
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
Fig. 4. Seasonal dynamics of the Chl concentration in the analyzed areas (5, 6, 7) located in the northwestern Black Sea (the bars
indicate the standard deviation).
was found, but, for the summer period, the trend was
slightly positive (Fig. 6).
An inverse relationship was found for the surface
water temperature and the chlorophyll concentration
averaged for 2week periods within the calendar year
(Fig. 7). In the wintertime, the chlorophyll concentra
tion might have differed by several times, but the water
temperature remained the same, although this vari
ability was minimal when the water temperature
ranged from 20 to 27°C in the summer. Generally, the
chlorophyll concentration in the summer was more
stable and did not depend on the variability observed
in the cold season of the year. In the meantime, when
analyzing the period of December–March, an oppo
site relationship was observed for the average chloro
phyll concentration and the water temperature
(Fig. 8). In the eastern and the western Black Sea, this
relationship was much more pronounced than in the
anticyclonal gyre, where the winter peak of the phy
toplankton was limited mostly by the income of
micronutrients within the discharge of small rivers. In
the meantime, no correlation was observed between
the monthly average Ca and the average water temper
ature during this period. During different years,
Ca might differ by several times, but the water temper
ature was the same. Therefore, the analysis of the
longterm data evidenced the absence of a statistically
significant trend in the Ca variability in the open sea
areas. In the northwestern Black Sea, negative trends
were observed, which might be a sign of the decrease
of the anthropogenic load in the coastal marine eco
systems.
4. DISCUSSION
The general concept of the seasonal dynamics of
the phytoplankton in different areas of the Ocean was
synthesized in the 1940s–1960s [14]. According to this
theory, the phytoplankton growth rate depends on two
abiotic limiting factors: the photosynthetic active radi
ation (PAR) and the wind force, which determines the
depth of the mixed water layer and the transport of the
micronutrients from the deep water layers to the
surface. Therefore, the PAR, micronutrient concen
tration, and the depth of the upper mixed water layer
precondition the variability of the types of seasonal
cycles of the phytoplankton. In the oceanic areas of
the temperate climatic zone, the winter convection
reaches depths of 500–1000 m. Here, part of the phy
toplankton stock is transported by the turbulent diffu
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603
6
4
4
2
0
3
Ca, mg/m3
5
2
1
0
2.5
7
2.0
1.5
1.0
0.5
0
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
Fig. 5. Interannual trends of the Chl concentration in the areas affected by the Dnepr River (4), Danube River (5), and along the
continental slope (7).
0.6
1
2
3
Ca, mg/m3
0.5
0.4
0.6
0.2
0.1
98
00
02
04
06
98
00
02
04
06
98
00
02
04
06
Fig. 6. Interannual dynamics of the Chl concentration in the surface water layer in the deepsea areas of the Black Sea (1–3).
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FINENKO et al.
2.0
1.2
2
R = 0.7
1
1.0
1.6
0.8
r 2 = 0.83
1.2
0.4
6
7
8
9
1.1
2
1.0
0.8
Ca, mg/m3
Ca, mg/m3
0.6
0.4
0.9
r 2 = 0.38
0.8
0.7
0.6
0
5
10
15
T, °C
20
25
30
Fig. 7. Relationship between the Chl concentration and
the water temperature in the surface water layer in 1998–
2008.
0.5
8.0
1.2
8.4
8.8
9.2
9.6
3
1.0
r 2 = 0.25
0.8
0.6
sion from the photosynthetic zone to the deep sea,
where photosynthesis is impossible due to the absence
of PAR. As a result, the phytoplankton biomass in the
wintertime exhibits its minimum. The increase of the
PAR, together with the decrease of the wind force,
promotes the decrease of the thickness of the upper
mixed layer. Most of the phytoplankton remain in the
photic zone and receive enough PAR and micronutri
ents, which leads to the spring phytoplankton bloom.
The calculation of the chlorophyll concentration
according to the satellite data allows scanning the sur
face of the sea with high frequency and, therefore,
tracking the peculiarities of the annual dynamics of
the phytoplankton. The annual cycle of Ca in the
deepsea areas of the Black Sea and on the shelves of
the Anatolian, Caucasian, and Crimean coasts may be
described by a Ushape curve. The comparison of the
satellite data and the monitoring observations in situ
performed simultaneously in the open sea fits nicely
the pattern described earlier [7]. The results of long
term observations performed in the vicinity of the
Bosporus Strait in 1996–2001 [13] evidenced a chloro
phyll maximum registered in the autumn and winter,
while a minimum in the summer. Similar seasonal
dynamics were described under the annual observations
made close to Sinop Cape in 2001–2004 [13] and in the
deepsea area of the Black Sea, when the data obtained
by the MODIS satellite scanner were analyzed [10].
However, some mismatching of the absolute values of
Ca were observed for the cold period of 2003–2004. The
different bands of the spectra used in assessing the chlo
0.4
8.8
9.2
9.6
10.0
T, °C
10.4
10.8
Fig. 8. Relationship between the average concentration of
Chl and the water temperature in the cold season (Decem
ber–March) in the deepsea area in 1998–2008.
rophyll concentration of the remote sensing data may
be one of the reasons for such a mismatch.
Therefore, the seasonal dynamics of the Ca in the
deep sea described by the satellite data and in situ
observations nicely fit each other.
The seasonal cycles of Ca differ in the Black Sea
and in the open oceanic waters of the temperate cli
matic zone. In the open ocean, two peaks of phy
toplankton are usually observed: in late spring and in
autumn. Oppositely, in the Black Sea, the seasonal
cycle of chlorophyll a is preconditioned by the depth
of the major picnocline, which coincides with the
lower depth of the photosynthetic layer, and by the
increase of the vertical upward flux of the micronutri
ents from the deep sea to the surface in the wintertime
[2, 5, 8]. The high position of the major picnocline
located close to the photosynthetic zone allows keep
ing the phytoplankton within the euphotic zone, and
the flux of the micronutrients promotes rapid growth
of the microalgae. In the oceanic waters of the temper
ate climatic zone, the major picnocline is located sig
nificantly deeper than in the Black Sea. As a result,
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part of the phytoplankton is permanently transported
downwards by the turbulent diffusion and penetrates
below the photosynthetic zone, and no increase of the
phytoplankton biomass is observed in the surface water
layer in the winter. This process implies that the maxi
mal Ca and phytoplankton biomass are to be expected
with high probability during the years of harsh winters
and strong winds, as was observed in 1986–1992, 1998,
and 2003–2004 in the centers of cyclonic gyres [12].
We suppose that the intensity and duration of the
phytoplankton bloom are preconditioned by mostly
the PAR and the depth of the mixed layer, which is a
result of both the water temperature conditions and
the wind force. However, both the PAR and wind force
may differ greatly even within the smallscale areas,
which leads to the absence of relationships between Ca
and the water temperature within a short time period.
In the meantime, the average Ca calculated for the
longer time period (December–March) depends on
the average water temperature of the same period. Par
ticularly, Ca increases as the water cools down in the
deepsea areas of the Black Sea (region nos. 1–3) and
in the coastal area (no. 4), but, in Danube River Delta
area (no. 5), a straight relationship is observed. In the
summertime (June–August), the Ca variability is not
linked to the climatic temperature fluctuations.
ACKNOWLEDGMENTS
The authors are grateful to NASA/GSFC/OBPG
for the opensource data.
This study was supported by the projects Funda
mental Problems of RealTime Oceanography and
Applying Satellite Data for the Biological Monitoring
of the Black Sea of the National Academy of Sciences
of Ukraine.
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Translated by D. Martynova