www.cerf-jcr.org
Trophic Characterization of the Pelagic Ecosystem inVlora Bay (Albania)
Olga Mangoni{, Francesca Margiotta{, Maria Saggiomo{, Immacolata Santarpia{,Giorgio Budillon1, and Vincenzo Saggiomo*{
{Universita di Napoli Federico IIvia Mezzocannone 880134 Napoli, Italy
{Stazione Zoologica Anton DohrnVilla Comunale, 80121 Napoli, [email protected]
1Universita di Napoli ParthenopeCentro Direzionale, Isola C480143 Napoli, Italy
ABSTRACT
MANGONI, O.; MARGIOTTA, F.; SAGGIOMO, M.; SANTARPIA, I.; BUDILLON, G., and SAGGIOMO, V. 2011. Trophiccharacterization of the pelagic ecosystem in Vlora Bay (Albania). In: Tursi, A. and Corselli, C. (eds.), Coastal Research inAlbania: Vlora Gulf, Journal of Coastal Research, Special Issue No. 58, pp. 67–79. West Palm Beach (Florida), ISSN0749-0208.
Phytoplankton assemblages were studied to characterize the trophic status of the semienclosed Vlora Bay (Albania) andto evaluate the influence of terrestrial inputs on its pelagic ecosystem. The study was carried out as part of the EuropeanProject CISM (INTERREG IIIA Italy–Albania) and conducted during two oceanographic cruises (spring 2007, winter2008). The size-fractionated chlorophyll a concentrations, primary production rates, and the chemotaxonomiccomposition (high-performance liquid chromatography) of the phytoplankton assemblages were measured. The spatialvariability of primary production rates and chlorophyll a concentrations both showed a pronounced E-W gradient in thesurface layer, with the highest values along the eastern coast. In spring, a deep chlorophyll maximum was observed inthe central western part of the bay, whereas in winter a homogeneous vertical distribution was observed. Thephytoplankton assemblages were quite similar in both seasons and were dominated by the picophytoplankton fraction(<46% and 53% in spring and in winter, respectively). Haptophytes and pelagophytes were the major phytoplanktongroups, and accounted, respectively, for 50% and 15% in spring, and 40% and 25% in winter. The results showed thatVlora Bay was characterized by generally oligotrophic conditions and that the influence of the southern Adriatic openwaters was negligible. The trophic characteristics of the pelagic ecosystem of the bay were essentially driven byterrestrial inputs.
ADDITIONAL INDEX WORDS: Primary production, phytoplankton biomass size-fractions, HPLC pigment spectra.
INTRODUCTION
Knowledge of the structural and functional properties of
microalgal communities is essential for the evaluation of the
ecological consequences of human activities for the trophic
state of marine ecosystems. Many authors (Kiørboe, 1993;
Legendre and Le Fevre, 1991; Malone, 1980) have highlighted
the fact that the size structure of phytoplankton assemblages
is a crucial control factor in the functioning of pelagic food
webs, and consequently, it affects the rate of carbon export
from the upper ocean to deep layers. Strict relationships have
been observed between environmental conditions and phyto-
plankton communities; for example, phytoplankton commu-
nities respond to changes in the physical and chemical
properties of their environment by changing their taxonomic
composition and size structure (Platt et al., 2005).
In coastal areas, these relationships are even more evident
because of the extreme variability of physical and chemical
parameters, and the effects of human activities such as
urbanization and tourism. In areas like the coastal regions of
Albania, which are subject to drastic socioeconomic changes,
and consequently, to an increasing and uncontrolled exploi-
tation of aquatic ecosystems (Munari et al., 2010), the
assessment of the structure and productivity of phytoplank-
ton assemblages is a crucial issue. Such assessments,
however, regarding the Albanian marine coastal waters are
relatively scarce (Mangoni, Saggiomo and Santarpia, 2003;
Rubino et al., 2009; Saracino and Rubino, 2006).
Vlora Bay, Albania, is a good site to carry out these
assessments because it is a semienclosed bay with a densely
populated industrial city, Vlora (Cullaj, Lazo, and Baraj, 2004;
Cullaj et al., 2005). The bay is connected to the open southern
Adriatic Sea by a very shallow entrance (,40-m depth), and is
south of the mouth of the Vjosa River whose waters flow
southerly past the Narta Lagoon and into the bay (Pano et al.,
2006) (Figure 1). In addition, the bay is of paramount interest
to the Albanian fishing industry since it serves as a natural
nursery for many fish species of economic importance.
To our knowledge, there are no data available regarding
the phytoplankton assemblages and the productivity of Vlora
Bay. The present study was carried out as part of the
European Project CISM (INTERREG IIIA Italy–Albania),
which aims at producing a detailed characterization of the
Vlora Bay ecosystem. The aim of the present study was to
DOI:10.2112/SI_58_7 received and accepted in revision 12 April2010.
* Corresponding author.E Coastal Education & Research Foundation 2011
Journal of Coastal Research SI 58 67–79 West Palm Beach, Florida Winter 2011
evaluate the structure and productivity of the phytoplankton
assemblages in Vlora Bay to assess the trophic characteristics
of the bay on small temporal and spatial scales. In particular,
size-fractionated biomass, chemotaxonomic composition, and
size-fractionated primary production are discussed in relation
to the physical and chemical environmental conditions of the
bay.
MATERIALS AND METHODS
Two oceanographic cruises (CISM_1, CISM_2) were carried
out in the Vlora Bay in spring 2007 (May 26–31; CISM_1) and
in winter 2008 (January 19–22; CISM_2) on board the ship R/
V Universitatis. Eight transects (A–H) were performed on
each cruise (Figure 1): five transects (A, B, C, D, E) were
intercoastal between the Karaburun Peninsula and the
mainland; one transect (G) was between the Karaburun
Peninsula and Sazan Island; and two transects (F, H) were
between Sazan Island and the Narta Lagoon. Conductivity,
temperature, and depth (CTD) profiles were acquired at all 34
stations: vertical profiles of temperature, salinity, oxygen,
and fluorescence were acquired using a SBE 911 Plus CTD
probe equipped with a SBE oxygen sensor and a Chelsea
fluorometer. On CISM_1, 19 biological stations were sampled,
and on CISM_2, 13 biological stations were sampled. All
samples were collected using a SBE 32 Carousel equipped
with 12-L Niskin bottles having Teflon-coated springs. Each
sampling depth was chosen on the basis of fluorescence
profile and water column structure. At each biological station,
profiles of underwater Photosynthetically Available Radia-
tion (PAR) were obtained using a LI-COR quantum meter to
determine optical levels (model LI-192SA).
Samples for the determination of inorganic nutrient (NO2,
NO3, NH4, PO4, SiO4) concentrations were collected directly
from the Niskin bottles and immediately stored at 220uCuntil analysis. The analyses were performed using a FlowSys
Systea autoanalyzer, following the procedure described by
Hansen and Grassoff (1983). Five litres of seawater were then
drawn from each Niskin bottle and, after careful mixing,
subsamples were separated for size-fractionated chlorophyll a
(Chl a) and primary production, for pigment spectra (high-
performance liquid chromatography [HPLC]), for particulate
organic carbon (POC), and for total particulate nitrogen (PN)
determinations.
Phytoplankton biomass fractionation was performed fol-
lowing a protocol of serial filtration. One subsample was
collected on a Whatman GF/F filter (GF/F tot); two subsam-
ples were passed through a Nitex net (20 mm mesh size) or a
Nuclepore membrane (2 mm pore size) and then collected on
Whatman GF/F filters, having either GF/F , 20 mm, or GF/F
, 2 mm, respectively. Microphytoplankton Chl a concentra-
tion was obtained subtracting the GF/F , 20 mm from the GF/
F tot reading; nanophytoplankton concentration was obtained
by subtracting the GF/F , 2 mm from the GF/F , 20 mm
reading; and the picophytoplankton Chl a concentration
directly from the GF/F , 2 mm. Vacuum was , 0.2 atm for
all filtration procedures. Filters were stored in liquid nitrogen
until analysis. The analyses of size-fractionated Chl a and
phaeopigments (Phaeo) were carried out according to Jeffrey
and Humphrey (1975) using a SHIMADZU (mod. RF-5301PC)
spectrofluorometer.
The measurement of primary production was performed in
in situ-simulated conditions. For each sampling depth, a
sample was transferred to two light and one dark polycarbon-
ate 300-ml bottles, and then inoculated with 370 kBq (10 Ci) of
NaH14CO3 and incubated for 4 hours around midday. Surface
samples were incubated in running surface seawater, and
subsurface samples were incubated in circulated seawater
maintained at the same temperature recorded at the sampling
depth. Incubation light levels were obtained by means of
neutral light screens. After incubation, size fractions were
isolated by differential filtration of three 100-ml subsamples,
as those for Chl a. The filters were stored at 220uC until
analysis. In the laboratory, the filters were acidified with 200 ml
of 0.1 N HCL, and after adding 10 ml of Aquasol II scintillation
cocktail, were read with a Packard Tri-Carb (mod. 2100TR)
liquid scintillator. Daily production was estimated by multi-
plying the ratio between the whole-day irradiance and the
irradiance during the incubation period. The irradiance was
measured by means of a quantum meter LI-COR (model LI-
190SA) during the entire sampling period.
One or two liters of seawater were filtered on GF/F
Whatman filters (47-mm diameter) and stored in liquid
nitrogen for HPLC analyses. The analyses were performed
according to Vidussi et al. (1996) using a Hewlett Packard
HPLC (1100 Series). Calibration of the instrument was
carried out using external standard pigments provided by
the International Agency for 14C determination—VKI Water
Quality Institute. The following biomarker pigments were
used as chemotaxonomic descriptors: alloxanthin (crypto-
phytes), chlorophyll b (chlorophytes), prasinoxanthin (prasi-
Figure 1. Sampling stations in Vlora Bay (southern Adriatic Sea): square,
biological stations sampled during CISM_1 (spring 2007) and CISM_2
(winter 2008); circle, biological stations sampled during CISM_1 (spring
2007); pentagon, CTD profiles (see Materials and Methods).
68 Mangoni et al.
Journal of Coastal Research, Special Issue No. 58, 2011
nophytes), 199-butanoyloxyfucoxanthin (pelagophytes), fuco-
xanthin (diatoms), 199-hexanoyloxyfucoxanthin (hapto-
phytes), peridinin (dinophytes), zeaxanthin (cyanobacteria),
and divinyl Chl a (prochlorophytes). The contribution of the
main phytoplankton groups to the total Chl a was estimated
on the basis of the concentrations of biomarker pigments
using the chemical taxonomy software CHEMTAX (Mackey et
al., 1996).
Subsamples for the determination of POC and PN were
filtered on Whatman GF/F precombusted (450uC, 5 h) glass
fibre filters. The filters were immediately stored at 220uC.
The filters were exposed to HCl vapours to remove the
inorganic carbonate fraction, and then were analysed with a
Thermo Electron CHN elemental analyzer (FlashEA 1112
Series) (Hedges and Stern, 1984). Cyclohexanone-2,4-dinitro-
phenyl hydrazone was used as standard.
Phytoplankton composition from CHEMTAX was analyzed
using the Primer5 v 5.2.9 (Plymouth Marine Laboratory,
U.K.) software. A nonlinear multidimensional scaling (MDS)
analysis, on the basis of the Bray–Curtis similarity matrix,
was performed to determine the presence of a pattern in the
phytoplankton assemblages. Principal component analyses
(PCA) based on a correlation matrix were used to investigate
the relationship between in situ physical and chemical
parameters (salinity and nutrients) and biological features
(Chl a, size classes, total primary production, and particulate
N and C). All analyses were performed with STATISTICA 6.0
software.
RESULTS
During the spring cruise (CISM_1), weather conditions
were mainly characterized by the wind blowing from the
southeast, and quite variable cloud cover. The incident light
varied from 25.8 (on May 27) to 46.9 mol photons d21 (on May
30). During the winter cruise (CISM_2), the first sampling
days were characterized by good weather conditions, and on
the last day the sky was quite cloudy. The incident light was
19.5 mol photons d21 on January 20, 18.0 mol photons d21 on
January 21, and decreased to 12.4 mol photons d21 on
January 22.
Physicochemical Parameters
The vertical profiles of temperature and salinity are
reported in Figure 2. Higher variations of temperature and
salinity were observed in spring (temperature: 22.96–
14.99uC; salinity: 36.92 and 38.47) (Figures 2a and b), as
compared with winter (temperature: 15.05–13.80uC; salinity:
38.01–38.43) (Figures 2c and d). The spatial distributions of
temperature and salinity in spring and winter for the surface
and bottom layers are reported in Figure 3. An E-W gradient
of temperature and salinity was very evident during both
seasons. More specifically, during the spring the E-W surface
gradient was characterized by low salinity and warm water in
the eastern and central areas, and by high salinity and cold
water in the western area (Figures 3a and c). The distribution
of these variables in the bottom layer was strictly related to
bathymetry, i.e., the presence of open-sea waters was evident
only in the deepest part of the bay (Figures 3b and d). During
the winter, the presence of open-sea waters was evident only
at the surface of the western area. The gradients were less
pronounced, and the eastern area was occupied by colder
waters (Figures 3e and g).
During both seasons, the concentrations of NO3 and PO4
were low and, at times, near or below the detection limits,
especially in spring (Table 1). In spring the vertical distribu-
tion of NO3 showed high variability (,0.01 to 0.42 mmol dm23),
with the highest values in the bottom layer. In contrast, NH4,
SiO4, and PO4 did not show any vertical gradient. During
winter, the vertical distribution of all inorganic nutrients was
quite homogeneous. NO3 showed higher concentrations than
in spring, and varied from 0.07 to 0.65 mmol dm23. The PO4
concentrations were similar to those observed in spring (avg.
5 0.03 mmol dm23). The SiO4 concentrations were relatively
low (range 4.36–0.97 mmol dm23) and similar in both seasons.
The NH4 concentrations were quite high in spring, as high as
0.87 mmol dm23, whereas in winter the mean concentration
was only half of that measured in spring.
Biological Parameters
During spring, the mean Chl a value was 0.25 mg m23
(60.16), and the vertical profiles showed the presence of a
deep chlorophyll maximum (DCM) in the deepest part of the
Figure 2. Vertical profiles of temperature (uC) (a,c) and salinity (b,d) in
spring and in winter, respectively.
Trophic Characterization of Vlora Bay 69
Journal of Coastal Research, Special Issue No. 58, 2011
Fig
ure
3.
Sp
ati
al
dis
trib
uti
onat
surf
ace
an
din
the
bot
tom
layer
ofte
mp
eratu
re(u
C)
(a,
b)
an
dsa
lin
ity
(c,
d)
insp
rin
g.
Sp
ati
al
dis
trib
uti
onof
tem
per
atu
re(u
C)
(e,
f)an
dsa
lin
ity
(g,
h)
inw
inte
r.
70 Mangoni et al.
Journal of Coastal Research, Special Issue No. 58, 2011
bay. During winter, the vertical distributions of phytoplank-
ton biomass were quite uniform (avg. 5 0.35 6 0.06 mg m23)
(Table 1; Figure 4). In spring, the surface spatial distribution
of Chl a showed high concentrations along the eastern coast of
the bay. In the bottom layer, the higher concentrations (max.:
0.84 mg m23, station C1, 248 m) were recorded in the deepest
part of the bay along the Karaburn Peninsula (Figures 5a and
b). In winter, the highest values of Chl a were recorded in the
eastern and central areas of the bay (Figures 5c and d). The
mean integrated values of Chl a were 11 and 13 mg m22 in
spring and in winter respectively.
The percentage contribution of different size classes to
phytoplankton biomass was quite similar in spring and
winter. There was an evident predominance of the picophy-
toplankton fraction of about 46% and 53% in spring and
winter, respectively. The mean contribution of the micro-
phytoplankton fraction was 12% (Table 1). During spring, an
anomalous high contribution (80%) of microphytoplankton
was observed in the bottom layer (248 m) of station C1. In
spring, the total phytoplankton biomass showed a good
correlation with the three size fractions (Figure 6a). Total
Chl a increase was mainly due to the increase of the
picofraction (slope 5 0.51; R 5 0.95, p , 0.001, n 5 58) and
the nanofraction (slope 5 0.33; R 5 0.89, p , 0.001, n 5 58),
and, to a lesser extent, to the increase of the microfraction
(slope 5 0.16; R 5 0.79, p , 0.001, n 5 58). In winter, the
nanofraction drove the biomass increase (slope 5 0.79; R 5
0.66, p , 0.001, n 5 31). No significant correlation was found
for the microphytoplankton (Figure 6b).
The results of CHEMTAX analyses showed that the
haptophytes were the major contributors to the biomass;
they accounted for 50% in spring and 38% in winter. The
results of the MDS analysis showed the presence of three
main groups. The winter samples were all very similar,
whereas the spring samples divided into two parts, separated
in the upper and deeper water layers, that is, above and below
the seasonal thermocline (Figure 7). The samples above the
thermocline showed a higher contribution of cyanobacteria
and diatoms (20% and 8%, respectively) and a lower
contribution of haptophytes (48%) and pelagophytes (12%)Table
1.
Ma
xim
um
,m
inim
um
,a
nd
aver
age
va
lues
ofte
mp
era
ture
,sa
lin
ity,
nu
trie
nts
,ch
loro
ph
yll
a(C
hl
a)
tota
l(T
OT
),m
icro
(.20
mm),
na
no
(20–2
mm),
an
dp
ico
(,2
mm),
an
dp
rim
ary
pro
du
ctio
n(P
P
tota
la
nd
fra
ctio
na
ted
as
for
Ch
la
)fo
rth
etw
ocr
uis
es(C
ISM
_1in
spri
ng
an
dC
ISM
_2in
win
ter)
.
NH
4
(mm
old
m2
3)
NO
2
(mm
old
m2
3)
NO
3
(mm
old
m2
3)
PO
4
(mm
old
m2
3)
SiO
4
(mm
old
m2
3)
TIN
(mm
old
m2
3)
Ch
la
TO
T
(mg
m2
3)
Ch
la
mic
ro(%
)
Ch
la
nan
o(%
)
Ch
la
pic
o(%
)
PP
TO
T
(mg
Cm
23
h2
1)
PP
mic
ro(%
)
PP
nan
o(%
)
PP
pic
o
(%)
CIS
M_1
(sp
rin
g)
Max
0.8
70.1
80.4
20.1
54.3
61.2
40.8
480
75
65
3.0
733
42
86
Min
0.2
0,
0.0
1,
0.0
1,
0.0
10.9
70.2
50.0
70
513
0.4
31
347
Avg
0.3
40.0
40.0
60.0
31.8
90.4
40.2
512
42
46
1.1
410
26
64
SD
0.0
90.0
40.0
90.0
20.7
60.1
80.1
611
10
10
0.4
47
97
CIS
M_2
(win
ter)
Max
0.3
00.4
50.6
50.0
64.1
70.9
90.4
927
69
74
2.0
027
55
90
Min
0.0
60.0
60.0
70.0
11.2
00.2
20.2
10
925
0.0
70
144
Avg
0.1
40.2
10.1
90.0
31.9
30.5
40.3
511
36
53
0.7
912
14
74
SD
0.0
50.1
00.0
90.0
10.4
50.1
90.0
68
14
11
0.5
07
11
8Figure 4. Vertical profiles of mean chlorophyll a and standard deviation
(a) in spring and (b) in winter in all stations.
Trophic Characterization of Vlora Bay 71
Journal of Coastal Research, Special Issue No. 58, 2011
as compared with those collected below the thermocline
(Figures 8a and b). The bottom layer (248 m) of station C1
showed peculiar features: a noticeable presence of diatoms
that accounted for up to 32% of the total biomass. The winter
samples were characterized by a higher contribution of
pelagophytes (avg. 24%) and prochlorophytes (avg. 6%) than
the spring samples (Figure 8c).
During the spring the primary production values ranged
from 0.43 to 3.07 mg C m23 h21, and had a mean value of
1.14 mgC m23 h21. The mean contributions of micro-, nano-,
Figure 5. Spatial distribution of chlorophyll a (mg m23) at surface and in the bottom layer in spring (a, b) and in winter (c, d).
72 Mangoni et al.
Journal of Coastal Research, Special Issue No. 58, 2011
and picophytoplankton were 10%, 26%, and 64%, respectively
(Table 1). The daily mean integrated values of primary
production varied from 6.28 mg C m23 d21 (station C1, in
the western central area) to 20.14 mg C m23 d21 (station
D5, off the city of Vlora) (Figure 9a). The primary produc-
tion rates in winter were low and varied from 0.07 to
2.0 mg C m23 h21, and the percentage contribution of
picophytoplankton was up to 74% (Table 1). The mean
integrated values varied from 1.34 mg C m23 d21 ( station
B2, in the SW area) to 9.23 mg C m23 d21 (station D5, near the
city of Vlora) (Figure 9b). The mean values of daily integrated
primary production for the entire bay were 389 and
134 mg C m22 d21 in spring and in winter, respectively.
In spring, the production/biomass (P/B) ratio varied from
0.88 to 9.06 mg C m23 h21 (mg m23 Chl a)21 (avg. 5.1 6 1.9).
The highest P/B values (.6 mg C m23 h21 [mg m23 Chl a]21)
were recorded at stratified surface layer. Below the thermo-
cline (average available light ,50 mmol photons m22 s21) the
photosynthetic capacity showed a slight decrease (avg.
3 mg C m23 h21 [mg m23 Chl a]21). In winter, the P/B values
were lower than in spring, ranging between 0.25 and
4.90 mg C m23 h21 (mg m23 Chl a)21 (avg. 2.2 6 1.2). The
POC and PN values differed in spring and in winter. During
spring, a considerable spatial variability in the surface
distributions of particulate C (coefficient of variation [CV] 5
49%) and N (CV 5 57%) was observed. The highest values
were recorded in the northern part of the bay (transects D, E,
F, and G), reaching 196 mg m23 of POC at station F3 and
36.6 mg m23 of PN at station G3; the average concentrations
of POC and PN were 136.9 mg m23 and 20.9 mg m23,
respectively. Lower concentrations of POC and PN (avg. 59.6
and 7.6 mg m23, respectively) were observed at the southern-
most stations of the bay (transects A, B, and C). The C/Chl a
ratio showed the same spatial distribution as the one
observed for POC concentrations: higher values (avg. 747)
were found in the northern area as compared with the
southern (avg. 316). During winter, particulate matter had a
homogeneous distribution: the coefficients of variability were
half of those encountered in spring (CV for POC 5 29% and
for PN 5 25%). The mean concentrations were 46.3 mg m23of
POC and 7.5 mg m23 of PN. The C/Chl a were considerably
lower in winter (avg. 5 138) as compared with those observed
in spring.
DISCUSSION
The Adriatic Sea is composed of a wide variety of
ecosystems, from the eutrophic conditions in the northwest
to oligotrophic conditions in the southeast. The dynamics of
these ecosystems are driven by the interactions between the
sea hydrodynamics and the discharge of nutrient-rich waters
from several rivers entering the sea. The river inputs strongly
influence both the circulation and the biogeochemical pro-
cesses of the entire Adriatic Sea (Degobbis and Gilmartin,
1990; Polimene et al., 2006). In addition, the Vlora Bay,
because of its position in the southeastern Adriatic Sea, is
also influenced by the waters coming from the eastern
Mediterranean, one of the most oligotrophic areas of the
world’s oceans (Allen, Blackford and Radford, 1998; Rele-
vante and Gilmartin, 1995).
The highly variable temperatures and salinity values
observed during the spring highlighted the complexity of
the bay’s hydrology that is due to the morphology of the
bottom and to the influence of land runoff. The shallow depths
in the channels connecting the open Adriatic sea to the bay
reduce the exchange of subsurface waters (,40 m) with the
southern Adriatic Sea. This factor has a major impact on the
ecology of the coastal ecosystem of the bay. The open South
Adriatic waters were primarily important in the surface layer
of the western part of the bay, whereas the influence of land
runoff was important in the eastern part. As a consequence,
an E-W salinity gradient was observed in both seasons. In
winter it occurred despite the vertical mixing of the water
column.
During the spring, the phytoplankton biomass showed a
mean value of 0.25 mg m23 (a range that is typical of the
oligotrophic areas; e.g., Li et al., 1983; Yacobi et al., 1995), and
a DCM at the bottom of the deepest stations (.40 m). The
surface spatial distribution of the phytoplankton biomass and
the primary production showed a clear E-W gradient, with
the highest concentrations along the eastern coast, thus
emphasizing the role of terrestrial input from the city of Vlora
and from the Narta Lagoon. These distributions were
Figure 6. Correlation between total Chl a and micro-, nano-, and pico- Chl
a concentrations (a) in spring and (b) in winter, for all sampling depths.
Trophic Characterization of Vlora Bay 73
Journal of Coastal Research, Special Issue No. 58, 2011
consistent with the temperature and salinity gradients. In
addition, the low PO4 and NO3 concentrations, which were
often near or below the detection limit, indicated a condition
of nutrient depletion. This nutrient depletion could suggest
that our spring cruise took place after an algal bloom. This
hypothesis is partially confirmed by the relatively high
phaeopigment and NH4 concentrations that are indices of
senescence and of grazing activity. However, it cannot be
excluded that the NH4 concentrations were due, at least in
part, to terrestrial input, as suggested by the relatively high
SiO4 concentrations.
In winter, the vertical distribution of Chl a was mainly due
to the water column dynamics. The phytoplankton biomasses
were uniformly distributed along the water column because of
the column’s isopycnal characteristics. This type of distribu-
tion is typical of winter phytoplankton distribution in the
open sea at temperate latitudes. It is interesting to notice that
the primary production rate was lower in winter than in
spring even though the chlorophyll concentration was higher
in winter. It should be excluded that these low primary
production rates were due to nutrient limitation, since (a) the
mean NO3 concentration was higher in winter than in spring,
and (b) the mean concentrations of PO4 and SiO4 were the
same in both seasons. It could be hypothesized that the low
winter primary production rates were due to the shorter
winter days and to the low irradiance availability. In fact, in
winter, the average light available during the incubations
was 300 mmol photons m22 s21 at the surface, and decreased
rapidly in the deep layers (at 15 m of depth it had already
decreased to ,50 mmol photons m22 s21).
To our knowledge, the data of the present study are the
first data available regarding primary production rates in the
Vlora Bay. To have some terms of comparison our data are
discussed in relation to the data available from two previous
studies of primary production. The first was conducted at a
semienclosed bay, located in the central Adriatic Sea, similar
to Vlora Bay, namely, the Kastela Bay (Croatia). In addition,
Kastela Bay has an ecological context similar to Vlora Bay in
that it is characterized by nearby intensive industrialization
and urbanization and low exchange with open sea waters
(Marasovic et al., 2005; Sestanovic, Solic, and Krstulovic,
2009; Vukadin and Stojanoski, 2004). The second was
conducted in the open waters of the southern Adriatic Sea
(Civitarese and Gacic, 2001). To better compare our data with
those available for Kastela Bay and for the open waters of
central and southern Adriatic Sea we considered only the
Figure 7. MDS analysis performed on a matrix of similarity between samples in terms of phytoplankton groups as derived from CHEMTAX (spring samples
above [black circle] and below [grey circle] the thermocline; [white circle] winter samples).
74 Mangoni et al.
Journal of Coastal Research, Special Issue No. 58, 2011
primary production rates of the deeper stations, in which the
whole euphotic zone (1% of incident light) was covered.
The mean daily primary production rates in the euphotic
zone of the Vlora Bay in January and in May (186 and
508 mg C m22 d21, respectively) were sensibly lower than
those reported for Kastela Bay for the same months (550 and
850 mg C m22 d21, respectively). These Vlora Bay rates,
however, were similar to those measured in the open waters
outside of Kastela Bay, the central Adriatic Sea (200 and
400 mg C m22 d21, respectively) (Marasovic et al., 2005).
Civitarese and Gacic (2001) analysed several data sets and
calculated the new winter primary production derived from
nitrate depletion in the euphotic layer in the open waters of
the southern Adriatic Sea for the years 1987–1999. The
primary production ranged from 29 g C m22 in 1988 and 1989
to 10 g C m22 in 1998. The highest rates of new primary
production were in winter (February–March), when convec-
tive mixing transfers nutrients from the deep reservoir to the
surface. The authors hypothesized that the rates of new
production depend upon the year-to-year variability of local
climatic conditions. These conditions, in fact, determine the
magnitude of convective mixing, and consequently, the
amount of nutrients available for primary producers. As a
result, low values of primary production were recorded during
mild winters when the vertical mixing was negligible. Winter
2007 was also mild according to Bensi, Cardin, and Civitare
(2009), and they reported the absence of the vertical mixing in
the southern Adriatic Sea. Following the same line of
reasoning regarding our spring cruise of the same year
(CISM_1; May 26–31, 2007), we hypothesize that the offshore
waters of the southern Adriatic Sea did not play any role in
driving primary production in Vlora Bay. On the basis of our
observations, we assume vertical mixing was negligible
during winter 2007, and thus nutrient enrichment of the
euphotic layer was relatively scarce. The winter cruise
(CISM_2; January 19–22, 2008) was carried out in the
preconditioning phase of vertical mixing (Civitarese and
Gagic, 2001). Without new nutrient enrichment of the
euphotic layer, the role of open waters in the trophism of
the Vlora Bay was, again, negligible.
Similar to the study by Civitarese and Gacic (2001), the
study of Marasovic et al. (2005) also hypothesized that the
influence of the local climatic conditions, which are probably
related to global change, play an important role in determin-
ing primary production rates. Our data strongly suggest that
this hypothesize may also apply to the Vlora Bay. Pico- and
nanophytoplankton fractions, essentially haptophytes, were
dominant in both seasons; however, some differences were
observed. In spring, moving along the water column, there
was a slight shift in the prokaryote community: the
prochlorophytes, almost completely absent in the surface
layer, accounted for the 4% of phytoplankton biomass below
the seasonal thermocline, and the contribution of cyanobac-
teria decreased. A similar pattern of occurrence has been
Figure 8. Average contribution of different microalgal groups to phyto-
plankton assemblages as identified by the MDS analysis; (a) above and (b)
below the thermocline, in spring; (c) in winter.
Figure 9. Spatial distributions of mean integrated primary production
(mg C m23 d21), (a) in spring and (b) in winter.
Trophic Characterization of Vlora Bay 75
Journal of Coastal Research, Special Issue No. 58, 2011
reported in the Gulf of Naples (Casotti et al., 2000) as well as
in other ecological contexts (Ting et al., 2002; Worden, Nolan,
and Palenik, 2004). This distribution is partially explained by
the higher sensitivity of prochlorophytes to ultraviolet
radiation, as Sommaruga et al. (2005) demonstrated in a
series of experiments on picoplankton populations in Medi-
terranean coastal waters. The occurrence of prochlorophytes
in the winter assemblage seems to be a recurrent feature in
the distribution of this group in the Mediterranean Sea
(Marty et al., 2002; Vaulot et al., 1990). It is interesting to
note the peculiar feature of the bottom layer at station C1
(248m), where the microphytoplankton fraction accounted
for 79.5% and diatoms contributed more than 35% to the total
biomass. We hypothesize that the deep accumulation of
phytoplankton biomass is due, in part, to the formation of a
DCM constituted by haptophytes, and to low hydrodynamics
in the area that favour the sedimentation of upper-layer
microplanktonic diatoms.
The chemical and biological properties of the water column
were strongly influenced by water column dynamics: in
Figure 10. Results of PCA applied to physical, chemical, and biological parameters (a) above and (b) below the thermocline, in spring. See text for
abbreviations of the parameters included in the analysis.
76 Mangoni et al.
Journal of Coastal Research, Special Issue No. 58, 2011
spring the thermal stratification separated the surface waters
from the bottom layer, whereas in winter a quite uniform
vertical distribution was observed. To assess the relationships
between physical, chemical, and biological parameters under
various water column conditions, we performed three multi-
variate analyses (PCA) applied to salinity, nutrients (SiO4,
NO3, NH4, PO4), Chl a (total, micro-, nano-, picophytoplank-
ton fractions), particulate matter (POC, PN), and primary
production rate. In the first PCA we analyzed the spring
samples above the thermocline (Figure 10a). We found that
(a) salinity and silicate were opposed on the first axis; (b) low-
salinity stations were characterized by high primary produc-
tion and high concentrations of NO3, SiO4, and Chl a; and (c)
the northernmost stations (transects G, F, D) presented a W-
E gradient characterized by a decrease in particulate matter
and salinity toward the east. In the second PCA we analyzed
the spring samples below the thermocline (Figure 10b). We
found that: (a) the salinity and silicate were strongly
correlated to the first axis, which separated the stations in
function of depth (. or ,40 m); (b) depth characterized also
the second axis with higher biological activity and biomass
abundance of small phytoplankton (nano- and picofractions);
(c) the sample collected at 248m depth of station C1 is
separated from all the other samples because of high
concentrations of large phytoplankton as reported above.
The third PCA was applied to all the winter samples
(Figure 11). In this season salinity was opposed on the first
axis to the chemical (NO3, SiO4, PO4) and biological
properties (Chl a, primary production rates, POC, PN,
nanophytoplankton).
In synthesis, the mechanisms operating during the spring
that drive the primary production processes are different in
the surface waters and in the bottom layers. In the surface
waters, the terrestrial inputs play a key role in modulating
phytoplankton growth. The eastern part of the bay, charac-
terized by lower salinity and higher nutrient concentrations,
showed the higher rates of primary production and biomass.
In the bottom layers, a reverse scenario was found: the higher
salinities were associated with higher nutrient concentra-
tions, relatively high primary production rates occurred in
the high-salinity waters, and these rates increased with
depth. In particular in the deeper stations the formation and
maintenance of the DCM during spring and summer were
typical of temperate areas. We hypothesize that the higher
nutrient concentrations are a kind of nutricline generated by
in situ recycling or resuspension of nutrients from the
seafloor sediments. If this is the case, then the incident light,
rather than the nutrients, may limit the microalgal produc-
tion. In winter the gradients along the water column were
less pronounced, the higher production rates occurred at low
salinity and high nutrient levels, and terrestrial inputs in the
eastern area were observed in the surface waters, as they
were also observed to be in spring.
During spring, the distribution patterns of particulate
matter (C and N) appeared completely uncoupled from the
other biological features in the surface layer; the N-S gradient
was very pronounced compared with the E-W gradient
observed for the other chemical and biological parameters.
The considerable POC and PN concentrations and the high C/
Chl a ratios in the northern area of the bay suggest the
presence of terrestrial inputs probably related to discharge
from the city of Vlora or from the Narta Lagoon. In contrast,
in winter and in the bottom layer in spring, characterized by
low C/Chl a ratios, it can be hypothesized that the biological
properties were coupled and the predominant fraction of POC
was due to phytoplankton.
Figure 11. Results of PCA applied to physical, chemical, and biological parameters in winter. See Figure 10.
Trophic Characterization of Vlora Bay 77
Journal of Coastal Research, Special Issue No. 58, 2011
CONCLUSIONS
N In spring 2007 and in winter 2008, Vlora Bay was
characterized by generally oligotrophic conditions and
highly variable primary production processes.
N The influence of the open southern Adriatic waters on the
trophism of the bay was negligible, whereas the influence
of terrestrial inputs was very pronounced. The distribution
of biomass at surface clearly showed the role of terrestrial
discharges from the eastern coast in driving primary
production processes. The bay was divided in two sections
along a SE-NW direction: the lowest values of both
phytoplankton biomass and production were recorded in
the western area.
N The trophic state was driven by local hydrodynamic
conditions, terrestrial nutrient inputs, and biogeochemical
cycles that were all mainly confined within the bay.
ACKNOWLEDGMENTS
We express our gratitude to Prof. A. Tursi for having
invited us to join this project. We also thank Augusto
Passarelli and Ciro Chiaese for their technical and logistical
support.
We are grateful to C. Brunet and M. Modigh for con-
structive criticism regarding the manuscript.
LITERATURE CITED
Allen, J.; Blackford, J., and Radford, P., 1998. A 1-D verticallyresolved modelling study of the ecosystem dynamics of the Middleand Southern Adriatic Sea. Journal of Marine Systems, 18, 265–286.
Bensi, M.; Cardin, V., and Civitare, G., 2009. Seasonal variability ofhydrological properties in the southern Adriatic sea during theVECTOR project (cruises 2006–2008). II Workshop Vector, Rome,11p.
Casotti, R.; Brunet, C.; Arnone, B., and Ribera d’Alcala, M., 2000.Mesoscale features of phytoplankton and planktonic bacteria in acoastal areas induced by external water masses. Marine EcologyProgress Series, 195, 15–27.
Civitarese, G. and Gacic, M., 2001. Had the Eastern MediterraneanTransient an impact on the new production in the southernAdriatic? Geophysical Research Letters, 28(8), 1627–1630.
Cullaj, A.; Hasko, A.; Miho, A.; Schanz, F.; Brandl, H., and Bachofen,R., 2005. The quality of Albanian natural waters and the humanimpact. Environmental International, 31, 133–146.
Cullaj, A.; Lazo, P., and Baraj, B., 2004. Investigation of mercurycontamination in Vlora Bay (Albania). Materials and Geoenviron-ment, 51(1), 58–62.
Degobbis, D. and Gilmartin, M., 1990. Nitrogen, phosphorus andsilicon budgets for the Northern Adriatic Sea. Oceanologica Acta,13, 31–45.
Hansen, H.P. and Grasshoff, K., 1983. Automated chemical analysis.In: Grasshoff, K.; Ehrardt, M., and Kremlin, K. (eds.), Methods ofSeawater Analysis. Weinheim: Chemie, pp. 347–379.
Hedges, J.I. and Stern, J.H., 1984. Carbon and nitrogen determina-tion of carbonate-containing solids. Limnology and Oceanography29, 657–663.
Jeffrey, S.W. and Humphrey, G.F., 1975. New spectrophotometricequations for determining chlorophylls a, b, c1 and c2 in higherplants, algae and natural phytoplankton. Biochemie und Physiolo-gie der Pflanzen, 167, 191–194.
Kiørboe, T., 1993. Turbulence, phytoplankton cell size, and thestructure of pelagic food webs. Marine Biology, 29, 1–72.
Legendre, L. and Le Fevre, J., 1991. From individual plankton cells topelagic ecosystems and to global biogeochemical cycles. In: Demers,S. (ed.), Particle Analysis in Oceanography. Berlin: Springer-Verlag, pp. 261–300.
Li, W.K.W.; Subba Rao, D.V.; Harrison, W.G.; Smith, J.C.; Cullen,J.J.; Irwin, B., and Platt T., 1983. Autotrophic picoplankton in thetropical ocean. Science, 219, 292–295.
Mackey, M.D.; Mackey, D.J.; Higgins, H.W., and Wright, S.W., 1996.CHEMTAX—a program for estimating class abundances fromchemical markers—application to HPLC measurements of phyto-plankton. Marine Ecology Progress Series, 144, 265–283.
Malone, T.C., 1980. Algal size. In: Morris, I. (ed.), The PhysiologicalEcology of Phytoplankton. Oxford: Blackwell Scientific Publica-tions, pp. 433–463.
Mangoni, O.; Saggiomo, M., and Santarpia I., 2003. Il trofismodell’Adriatico meridionale: distribuzione quali-quantitativa deipopolamenti fitoplanctonici lungo le coste pugliesi ed albanesi.Biologi Italiani, Anno XXXIII 1, 46–51 [in Italian].
Marasovic, I.; Nincevic, Z.; Kuspilic, G.; Marinovic, S., and Marinov,S., 2005. Long-term changes of basic biological and chemicalparameters at two stations in the middle Adriatic. Journal of SeaResearch, 54, 3–14.
Marty, J.C.; Chiaverini, J.; Pizay, M.D., and Avril, B., 2002. Seasonaland interannual dynamics of nutrients and phytoplankton pig-ments in the western Mediterranean Sea at the DYFAMED time-series station (1991–1999). Deep Sea Research II, 49, 1965–1985.
Munari, C.; Tessari, U.; Rossi, R., and Mistri, M., 2010. The ecologicalstatus of Karavasta Lagoon (Albania): closing the stable door beforethe horse has bolted? Marine Environmental Research, 69, 10–17.
Pano, N.; Frasheri, A.; Simeoni, U., and Frasheri, N., 2006. Outlookon seawaters dynamics and geological setting factors for theAlbanian Adriatic coastline developments. Albanian Journal ofNatural and Technical Sciences, 19/20, 152–166.
Platt, T.; Bouman, H.A.; Devred, E.; Fuentes-Yaco, C., and Sathyn-dranatah, S., 2005. Physical forcing and phytoplankton distribu-tions. Scientia Marina, 69, 55–73.
Polimene, L.; Pinardi, N.; Zavatarelli, M., and Colella, S., 2006. TheAdriatic Sea ecosystem seasonal cycle: validation of a three-dimensional numerical model. Journal of Geophysical Research,111, C03S19, doi:10.1029/2005JC003260.
Revelante, N. and Gilmartin, M., 1995. The relative increase of largerphytoplankton in a subsurface chlorophyll maximum of thenorthern Adriatic Sea. Journal of Plankton Research, 17, 1535–1562.
Rubino, F.; Saracino, O.D.; Moscatello, S., and Belmonte, G., 2009. Anintegrated water/sediment approach to study plankton (a casestudy in southern Adriatic Sea). Journal of Marine Systems, 78(4),536–546.
Saracino, O.D. and Rubino, F., 2006. Phytoplankton composition anddistribution along the Albanian coast, South Adriatic Sea. NovaHedwigia, 83(1–2), 253–266.
Sestanovic, S.; Solic, M., and Krstulovic, N., 2009. The influence oforganic matter and phytoplankton pigments on the distribution ofbacteria in sediments of Kastela Bay (Adriatic Sea). ScientiaMarina, 73(1), 83–94.
Sommaruga, R.; Hofer, J.S.; Alonso-Saez, L., and Gasol, J.M., 2005.Differential sunlight sensitivity of picophytoplankton from surfaceMediterranean coastal waters. Applied and Environmental Micro-biology, 71(4), 2154–2157.
Ting, C.S.; Rocap, G.; King, J., and Chisholm, S.W., 2002. Cyano-bacterial photosynthesis in the oceans: the origins and significanceof divergent light-harvesting strategies. Trends in Microbiology,10(3), 134–142.
Vaulot, D.; Partenski, F.; Neveux, J.; Mantoura, R.F.C., andLlewellyn, C.A., 1990. Winter presence of prochlorophytes insurface waters of the northern western Mediterranean Sea.Limnology and Oceanography, 35, 1156–1164.
Vidussi, F.; Claustre, H.; Bustillos-Guzman, J.; Cailliau, C., andMarty, J.C., 1996. Determination of chlorophylls and carotenoids ofmarine phytoplankton: separation of chlorophyll a from divinyl-chlorophyll a and zeaxanthin from lutein. Journal of PlanktonResearch, 18, 2377–2382.
78 Mangoni et al.
Journal of Coastal Research, Special Issue No. 58, 2011
Vukadin, I. and Stojanoski, L., 2004. Present water quality of KastelaBay (Adriatic Sea) and some proposals for its protection andimprovement. In: Briand, F. (ed.), Rapport du 37e Congres de laCommission Internationale pour l’Exploration Scientifique de lamer Mediterranee, Monaco: CIESM, 253p.
Worden, A.Z.; Nolan, J.K., and Palenik, B., 2004. Assessing thedynamics and ecology of marine picophytoplankton: the importance
of the eukaryotic component. Limnology and Oceanography. 49(1),168–179.
Yacobi, Y.Z.; Zohary, T.; Kress, N.; Hecht, A.; Robarts, R.D.; Waiser,M.; Wood, A.M., and Li, W.K.W., 1995. Chlorophyll distributionthroughout the southeastern Mediterranean in relation to thephysical structure of the water mass. Journal of Marine Systems, 6,179–189.
Trophic Characterization of Vlora Bay 79
Journal of Coastal Research, Special Issue No. 58, 2011
Top Related