Bacterial Abundance in the Adriatic Sea
479
fluoresce bright yellow while other picophytoplankton appear deep red. The HN emitting yellow fluorescence under blue excitation (410 to
485 nm with 515 nm barrier filter) and blue fluorescence under UV excitation were counted for
at least 20 fields; over 100 cells per filter were
counted.
(Kruskal Wallis test, P<0.05).
Seasonal patterns are shown in Fig. 2. During
spring the bacterial density (median value of all
the determinations) was similar to north, central
and south Adriatic areas, while the lowest abundance in the Otranto Strait significantly differed
(Kruskal Wallis test; P
observed in spring. During autumn bacterial
densities decreased in the whole basin and particularly in the Northern Adriatic. In winter
increasing abundances were observed in north
and central basin while they remained constant
in the most southern areas.
Results
Bacterial abundance data used in this study are
summarized in Table 1. The average density values along the water column ranged from 1 x lOs
to 1.6 x10 6 cell mL -lover the four transects.
There were significant differences among coastal
and off-shore stations along each of the transects
Picophytoplankton abundance ranged
between 2.8 x 10 3 to 5.6 X 10 4 cell mL- i . Both
Thble 1. Bacterial abundance (106 cell mLl): each datum represents the mean value and standard deviation (SD) of bacterial
densities along the water column
Station
Spring
Summer
Autumn
Winter
Mean
SD
Mean
SD
Mean
SD
Mean
SD
B01
0.780
0.107
1.614
1.096
0.326
0.086
0.467
0.132
B02
1.332
0.632
0.432
0.114
0.613
0.183
B03
0.495
0.169
0.546
0.157
0.207
0.060
0.502
0.086
BOS
0.246
0.032
0.389
0.181
0.203
0.038
0.656
0.647
B07
0.241
0.057
0.492
0.214
0.232
0.091
0.607
0.250
BOS
0.922
0.365
0.164
0.076
0.692
0.287
B09
0.252
0.081
0.913
0.239
0.291
0.083
0.632
0.276
BI0
0.512
0.074
0.258
0.127
0.816
0.320
Bll
0.157
0.OS9
0.451
0.259
0.120
0.061
0.662
0.081
B12
0.362
0.060
0.785
0.123
0.105
0.027
0.477
0.140
E02
0.325
0.066
1.091
0.353
0.279
0.175
1.019
0.123
E03
0.254
0.081
0.714
0.187
0.233
0.170
0.477
0.139
E05
0.288
0.095
0.850
0.200
0.244
0.093
0.530
0.116
E06
0.281
0.150
0.681
0.140
0.366
0.105
0.223
0.051
EOB
0.275
0.054
0.432
0.180
0.561
0.143
0.538
0.063
E09
0.400
0.172
0.781
0.163
0.520
0.243
0.490
0.147
Ell
0.279
0.064
0.774
0.306
0.244
0.063
0.448
0.127
El2
0.402
0.155
0.666
0.202
0.696
0.183
0.551
0.127
H02
0.227
0.121
0.827
0.216
0.614
0.228
0.462
0.167
H04
0.226
0.106
0.902
0.352
0.464
0.173
0.492
0.187
H06
0.295
0.060
0.646
0.226
·0.435
0.148
0.176
0.070
H08
0.333
0.053
0.335
0.132
0.343
0.148
0.110
0.325
HIO
0.354
0.113
0.642
0.311
0.383
0.137
0.325
0.187
Hl2
0.300
0.094
0.590
0.233
0.263
0.138
0.326
0.079
MOl
0.488
0.170
1.017
0.226
0.794
0.348
0.154
0.041
M03
0.313
0.042
0.739
0.202
0.743
0.263
0.159
0.106
M05
0.195
0.079
0.584
0.245
0.563
0.369
0.297
0.122
M07
0.114
0.084
0.442
0.215
0.411
0.232
0.104
0.048
M09
0.137
0.077
0.396
0.271
0.420
0.233
0.239
0.148
MIl
0.169
0.104
0.390
0.232
0.220
0.144
0.229
0.130
479
fluoresce bright yellow while other picophytoplankton appear deep red. The HN emitting yellow fluorescence under blue excitation (410 to
485 nm with 515 nm barrier filter) and blue fluorescence under UV excitation were counted for
at least 20 fields; over 100 cells per filter were
counted.
(Kruskal Wallis test, P<0.05).
Seasonal patterns are shown in Fig. 2. During
spring the bacterial density (median value of all
the determinations) was similar to north, central
and south Adriatic areas, while the lowest abundance in the Otranto Strait significantly differed
(Kruskal Wallis test; P
observed in spring. During autumn bacterial
densities decreased in the whole basin and particularly in the Northern Adriatic. In winter
increasing abundances were observed in north
and central basin while they remained constant
in the most southern areas.
Results
Bacterial abundance data used in this study are
summarized in Table 1. The average density values along the water column ranged from 1 x lOs
to 1.6 x10 6 cell mL -lover the four transects.
There were significant differences among coastal
and off-shore stations along each of the transects
Picophytoplankton abundance ranged
between 2.8 x 10 3 to 5.6 X 10 4 cell mL- i . Both
Thble 1. Bacterial abundance (106 cell mLl): each datum represents the mean value and standard deviation (SD) of bacterial
densities along the water column
Station
Spring
Summer
Autumn
Winter
Mean
SD
Mean
SD
Mean
SD
Mean
SD
B01
0.780
0.107
1.614
1.096
0.326
0.086
0.467
0.132
B02
1.332
0.632
0.432
0.114
0.613
0.183
B03
0.495
0.169
0.546
0.157
0.207
0.060
0.502
0.086
BOS
0.246
0.032
0.389
0.181
0.203
0.038
0.656
0.647
B07
0.241
0.057
0.492
0.214
0.232
0.091
0.607
0.250
BOS
0.922
0.365
0.164
0.076
0.692
0.287
B09
0.252
0.081
0.913
0.239
0.291
0.083
0.632
0.276
BI0
0.512
0.074
0.258
0.127
0.816
0.320
Bll
0.157
0.OS9
0.451
0.259
0.120
0.061
0.662
0.081
B12
0.362
0.060
0.785
0.123
0.105
0.027
0.477
0.140
E02
0.325
0.066
1.091
0.353
0.279
0.175
1.019
0.123
E03
0.254
0.081
0.714
0.187
0.233
0.170
0.477
0.139
E05
0.288
0.095
0.850
0.200
0.244
0.093
0.530
0.116
E06
0.281
0.150
0.681
0.140
0.366
0.105
0.223
0.051
EOB
0.275
0.054
0.432
0.180
0.561
0.143
0.538
0.063
E09
0.400
0.172
0.781
0.163
0.520
0.243
0.490
0.147
Ell
0.279
0.064
0.774
0.306
0.244
0.063
0.448
0.127
El2
0.402
0.155
0.666
0.202
0.696
0.183
0.551
0.127
H02
0.227
0.121
0.827
0.216
0.614
0.228
0.462
0.167
H04
0.226
0.106
0.902
0.352
0.464
0.173
0.492
0.187
H06
0.295
0.060
0.646
0.226
·0.435
0.148
0.176
0.070
H08
0.333
0.053
0.335
0.132
0.343
0.148
0.110
0.325
HIO
0.354
0.113
0.642
0.311
0.383
0.137
0.325
0.187
Hl2
0.300
0.094
0.590
0.233
0.263
0.138
0.326
0.079
MOl
0.488
0.170
1.017
0.226
0.794
0.348
0.154
0.041
M03
0.313
0.042
0.739
0.202
0.743
0.263
0.159
0.106
M05
0.195
0.079
0.584
0.245
0.563
0.369
0.297
0.122
M07
0.114
0.084
0.442
0.215
0.411
0.232
0.104
0.048
M09
0.137
0.077
0.396
0.271
0.420
0.233
0.239
0.148
MIl
0.169
0.104
0.390
0.232
0.220
0.144
0.229
0.130