202
K.-S. Jeong . F. Recknagel . G.-J. Joo
Table 10.2. Limnological characteristics of the lower Nakdong River for five
years (1994-1998). " means ± SD (n = 263; 52-53 in each year).
Division
Parameters
Unit
Mean±SD
5 ~ears'
1994
1995
1996
1997
1998
Meteorologieal
Irradianee
MJm-'dai l
12.8±6-5·
14±7
14±6
12±6
13±6
12±6
Air tem~rature 'Cdat l
15±8
16±9
15±8
15±8
15±8
16±8
Precipitatioo
mmdai I
974±306
765
841
1007
1352
1670
Hydrologieal
Discharge
CMS
567±714
399±79
466±358
488±480
686±825
794± 11 84
Eva~ration
mmdai l
3±2
4±2
3±2
3±2
3±2
3±1
Water
'C
17±9
20±1O
16±1O
17±1O
18±9
17±8
Physieal
temperature
Secehi depth
em
74±25
72±22
75±20
74±22
74±32
74±23
Turbidit~
NTU
18±54
20±64
12±35
9±9
19±38
27±91
pH
8.4±O.8
8.7±0.9
8.3±0.6
8.4±O.7
8-5±0.8
8.0±0.8
DO
mgL-l
1O.8±4.0
9.9±3.8
11.4±3.6
11.9±3.9
1O.2±4-5
1O.5±3.4
Cooduetivity
JlS cm- I
349±128
312±92
405± 11 8
396±1I4
374±146
250±76
Chemieal
Alkalinity
mgCaCO,L- l
57±17
55±13
66±13
67±13
58±17
41±9
Nitrate-N
mgL- l
2.7±1.0
1.8±O.9
2.5±1.0
2.3±1.0
3.3±O.8
3.2±0-5
Ammonia-N
mgL-l
0.6±O.7
0.3±O.3
0_8±0.8
0.7±O.6
0.3±0.3
0.8±1.0
Phosphate-P
~gL-l
34.7±25.2 33.1±22.1 34.3±25.2 20-5±15.2 32.7±23.0 52.8±27_9
Siliea
mgL- l
4.3±3.8
3.6±2.3
2.6±2.8
3.0±2.3
4.6±4.2
7.5±4.4
Rotifera
iod. L- l
1644±325 1241±208 1285±176 1021±127 3046±571 1304±174
0
6
4
4
3
7
Cladocera
iod. L- l
91±311
25±58
201±588
71±176
79±140
30±61
Copepoda
iod. L- l
6O±151
23±43
65±147
43±67
109±251
36±62
Biologieal
M. aeruginosa.
XIO'~'mL-l
2.84±12.3 5.34±18.8 1.42±3.08
3.66±11.5 3.64±15.8 0.15±O.39
4
I
I
2
s. hantzschii
XIO'~'mL-l
15.10±24.14
12.97±26.74
17.24±29.42
20.89±27.11
10.22<22.88
9.50±11.48
Chlorophyll a
~gL-l
50.2±91.5
84.7±178. 65.5±74.7 48-5±49.2 37-5±80.6 28.0±26.4
5
Overall phytoplankton dynamics were strongly influenced by magnitudes and
timing of M. aeruginosa and S. hantzschii blooms. Annual average biovolumes of
M. aeruginosa and S. hantzschii peaked in years with low annual precipitation. M.
aeruginosa especially proliferated during the extreme drought of 1994, while the
peak biovolume of S. hantzschii occurred in the winter of 1996. Both M.
aeruginosa and S. hantzschii accounted far 80% of the phytoplankton abundance
as a result of fast growth in the summer and winter, respectively. During blooms,
these two species accounted far mare than 90% of the algal abundance.
Microcystis spp. rarely forms blooms in flowing water systems except pool-like
and sluggish rivers (see Reynolds 1992). Even though centric diatoms such as S.
hantzschii were found widely in river systems (Lack 1971; Moss and Balls 1989;
Köhler 1994; Murakami 1998), there have been almost no reports of winter
Stephanodiscus blooms. Ha et al. (1999) reported that hydrologie stagnation in the
Nakdong River influenced phytoplankton dynamics. In particular, the Microcystis
bloom formation was directly related to the importance of hydrodynamies and
nutrient loading. The Stephanodiscus proliferation may be due to combined
factors such as cold temperature, low flow, and high availability of dissolved
silica.
K.-S. Jeong . F. Recknagel . G.-J. Joo
Table 10.2. Limnological characteristics of the lower Nakdong River for five
years (1994-1998). " means ± SD (n = 263; 52-53 in each year).
Division
Parameters
Unit
Mean±SD
5 ~ears'
1994
1995
1996
1997
1998
Meteorologieal
Irradianee
MJm-'dai l
12.8±6-5·
14±7
14±6
12±6
13±6
12±6
Air tem~rature 'Cdat l
15±8
16±9
15±8
15±8
15±8
16±8
Precipitatioo
mmdai I
974±306
765
841
1007
1352
1670
Hydrologieal
Discharge
CMS
567±714
399±79
466±358
488±480
686±825
794± 11 84
Eva~ration
mmdai l
3±2
4±2
3±2
3±2
3±2
3±1
Water
'C
17±9
20±1O
16±1O
17±1O
18±9
17±8
Physieal
temperature
Secehi depth
em
74±25
72±22
75±20
74±22
74±32
74±23
Turbidit~
NTU
18±54
20±64
12±35
9±9
19±38
27±91
pH
8.4±O.8
8.7±0.9
8.3±0.6
8.4±O.7
8-5±0.8
8.0±0.8
DO
mgL-l
1O.8±4.0
9.9±3.8
11.4±3.6
11.9±3.9
1O.2±4-5
1O.5±3.4
Cooduetivity
JlS cm- I
349±128
312±92
405± 11 8
396±1I4
374±146
250±76
Chemieal
Alkalinity
mgCaCO,L- l
57±17
55±13
66±13
67±13
58±17
41±9
Nitrate-N
mgL- l
2.7±1.0
1.8±O.9
2.5±1.0
2.3±1.0
3.3±O.8
3.2±0-5
Ammonia-N
mgL-l
0.6±O.7
0.3±O.3
0_8±0.8
0.7±O.6
0.3±0.3
0.8±1.0
Phosphate-P
~gL-l
34.7±25.2 33.1±22.1 34.3±25.2 20-5±15.2 32.7±23.0 52.8±27_9
Siliea
mgL- l
4.3±3.8
3.6±2.3
2.6±2.8
3.0±2.3
4.6±4.2
7.5±4.4
Rotifera
iod. L- l
1644±325 1241±208 1285±176 1021±127 3046±571 1304±174
0
6
4
4
3
7
Cladocera
iod. L- l
91±311
25±58
201±588
71±176
79±140
30±61
Copepoda
iod. L- l
6O±151
23±43
65±147
43±67
109±251
36±62
Biologieal
M. aeruginosa.
XIO'~'mL-l
2.84±12.3 5.34±18.8 1.42±3.08
3.66±11.5 3.64±15.8 0.15±O.39
4
I
I
2
s. hantzschii
XIO'~'mL-l
15.10±24.14
12.97±26.74
17.24±29.42
20.89±27.11
10.22<22.88
9.50±11.48
Chlorophyll a
~gL-l
50.2±91.5
84.7±178. 65.5±74.7 48-5±49.2 37-5±80.6 28.0±26.4
5
Overall phytoplankton dynamics were strongly influenced by magnitudes and
timing of M. aeruginosa and S. hantzschii blooms. Annual average biovolumes of
M. aeruginosa and S. hantzschii peaked in years with low annual precipitation. M.
aeruginosa especially proliferated during the extreme drought of 1994, while the
peak biovolume of S. hantzschii occurred in the winter of 1996. Both M.
aeruginosa and S. hantzschii accounted far 80% of the phytoplankton abundance
as a result of fast growth in the summer and winter, respectively. During blooms,
these two species accounted far mare than 90% of the algal abundance.
Microcystis spp. rarely forms blooms in flowing water systems except pool-like
and sluggish rivers (see Reynolds 1992). Even though centric diatoms such as S.
hantzschii were found widely in river systems (Lack 1971; Moss and Balls 1989;
Köhler 1994; Murakami 1998), there have been almost no reports of winter
Stephanodiscus blooms. Ha et al. (1999) reported that hydrologie stagnation in the
Nakdong River influenced phytoplankton dynamics. In particular, the Microcystis
bloom formation was directly related to the importance of hydrodynamies and
nutrient loading. The Stephanodiscus proliferation may be due to combined
factors such as cold temperature, low flow, and high availability of dissolved
silica.