Variability in seasonal cycles of zooplankton in
the seas surrounding Korean peninsula
Kang, Young Shil
National Fisheries Research & Development Institute
Contents
V Background and Hypotheses
V Method and Data
V Results
– Geographical difference in Seasonal variation
– Seasonal variation in response to regime shifts
V Conclusion
Background & hypotheses
V Background
– Three Seas with different physical characteristics
– Respond to regime shifts
V Hypotheses
– Seasonal cycles will respond differently to spatial
scale with different physical characteristics
– Seasonal cycles will respond differently to regime
shifts
Data and Method
V Zooplankton collection
– Hauling vertically with NORPAC net (0.33mm mesh size and
0.5m mouth diameter) from bottom or 100m depth to surface
– 6 times in a year (February, April, June, August, October and
December)
V Zooplankton biomass
– Express as the wet weight of zooplankton, smaller than 3 cm in
body size per cubic meter
V Data
– Zooplankton biomass : 1965~2000
– Abundance of four zooplankton groups : 1978-2000
(Copepoda, Amphipoda, Chaetognatha and
Euphausiid)
V Statistics
– Duncan’s multiple comparison test (Based on one-way ANOVA
–test; SPSS Version 10.0)
– Self-Organizing Mapping (SOM; Kohonen, 2001)
Map & sampling stations
East/Japan Sea
Yellow Sea
East China Sea
Characteristics of three seas
V East / Japan Sea :
– Deep
– East Korea Warm Current ( Branch of Tsushima
Warm Current )
– North Korea Cold Current
– Polar Front
– Coastal upwelling
V Yellow Sea :
– Shallow (Mean depth=44m)
– Yellow Sea Warm Current intrudes from East
China Sea episodically in winter
– Large tidal ranges, strong tidal fronts and tidal
currents
V Northern East China Sea :
– Shallow (less than 100m depth)
– Tsushima Warm Current
– Low-salinity Yangtze River water
– Coastal fronts
– Strong water exchange with East /Japan Sea
– Weak water exchange with Yellow Sea
Seasonal variation in geographical
distributions
February
April
June
October
August
December
Seasonal variations in zooplankton biomass in
three seas combined (Korean waters)
Zooplankton biomass (㎎/㎥
200
a
ab
150
b
c
100
d
d
50
r
be
ec
em
D
O
ct
ob
er
gu
st
ne
Ju
Ap
ril
Au
Fe
br
ua
ry
0
Month
•Different letters indicate significantly different mean (Duncan’s multiple
comparison test; p<0.05).
300
a
a
250
200
b
bc
150
a
100
cd
a
d
c
50
b
bc
bc
bc
bc
bc
ab
d
c
Eas t/Japan Sea
r
em
ec
D
Month
Eas t China Sea
be
er
ob
ct
O
A
ug
us
t
ne
Ju
pr
A
ua
Fe
br
il
0
ry
Zooplankton biomass (㎎/㎥)
Seasonal variations in zooplankton biomass in each sea
Yellow Sea
•Different letters indicate significantly different mean (Duncan’s multiple
comparison test; p<0.05).
™ Synopsis : Seasonal peaks of zooplankton
biomass
Sea
East/Japan Sea
Northern East
China Sea
Yellow Sea
Month
February,
April
(October)
April
(October)
June
(October)
Seasonal variations in abundance of zooplankton groups
in three seas combined (Korean waters)
Copepoda
Amphipoda
Chaetognatha
Euphausiid
February
April
June
August
October December
D
B
A
CD
D
CD
(n=1,640;
76±112)
(n=1,732;
174±359)
(n=1,742;
325±1,403)
(n=1,751;
104±176)
(n=1,758;
128±185)
(n=1,542;
95±157)
C
C
A
BC
AB
BC
(n=1,647;
1.3±4.4)
(n=1,738;
1.6±6.9)
(n=1,750;
6.2±50.3)
(n=1,755;
3.2±10.8)
(n=1,759;
5.1±80.6)
(n=1,549;
3.4±8.7)
C
D
D
A
B
CD
(n=1,647;
32.3±148.9)
(n=1,738;
14.4±62.9)
(n=1,751;
14.0±83.8)
(n=1,755;
70.8±380.1)
(n=1,758;
128±185)
(n=1,542;
95±157)
B
A
A
B
B
B
(n=1,646;
3.5±37.2)
(n=1,738;
10.7±154.5)
(n=1,751;
16.3±191.6)
(n=1,755;
2.5±16.4)
(n=1,760;
2.3±16.4)
(n=1,549;
3.1±6.5)
•Different letters indicate significantly different mean (Duncan’s multiple comparison test; p<0.05).
Seasonal variations in abundance of zooplankton groups
in the East/Japan Sea
Copepoda
Amphipoda
Chaetognatha
Euphausiid
February
April
June
August
October December
C
A
B
C
C
C
(n=683;
66±112)
(n=724;
141±311)
(n=728;
111±410)
(n=754;
72±98)
(n=727;
70±77)
(n=691; 70±90)
C
C
A
B
B
B
(n=683;
2.0±4.2)
(n=724;
2.3±8.4)
(n=728;
5.5±17.7)
(n=754;
3.4±8.2)
(n=727;
4.0±8.4)
(n=691;
3.8±8.2)
C
C
B
A
A
B
(n=683;
1.5±4.3)
(n=724;
1.3±2.6)
(n=728;
2.5±4.7)
(n=754;
4.0±7.1)
(n=727;
4.4±11.4)
(n=691;
3.1±8.8)
C
A
B
AB
AB
C
(n=683;
0.7±1.5)
(n=724;
1.9±3.8)
(n=728;
1.5±4.2)
(n=754;
1.8±4.8)
(n=727;
1.8±4.9)
(n=691;
0.9±3.8)
•Different letters indicate significantly different mean (Duncan’s multiple comparison test; p<0.05).
Seasonal variations in abundance of zooplankton groups
in the Northern East China Sea
Copepoda
Amphipoda
Chaetognatha
Euphausiid
February
April
June
August
October December
C
A
B
C
A
A
(n=465;
89±124)
(n=513;
197±290)
(n=496;
121±164)
(n=480;
87±89)
(n=516;
179±211)
(n=439;
175±248)
D
C
B
B
A
A
(n=471;
0.5±1.5)
(n=519;
1.9±7.5)
(n=505;
3.3±7.1)
(n=484;
3.1±7.1)
(n=518;
4.7±9.2)
(n=446;
4.7±9.2)
E
E
D
B
A
C
(n=472;
1.2±2.4)
(n=519;
1.6±4.5)
(n=505;
3.0±5.9)
(n=484;
6.2±10.2)
(n=518;
8.3±14.0)
(n=446;
4.7±8.8)
D
A
B
BC
BC
C
(n=472;
0.5±1.8)
(n=519;
5.2±14.8)
(n=505;
3.2±7.9)
(n=484;
2.7±11.5)
(n=518;
2.6±5.9)
(n=446; 1.7±4.1)
•Different letters indicate significantly different mean (Duncan’s multiple comparison test; p<0.05).
Seasonal variations in abundance of zooplankton groups
in the Yellow Sea
Copepoda
Amphipoda
Chaetognatha
Euphausiid
February
April
June
August
October Decembe
r
C
B
A
B
B
C
(n=542;
73±94)
(n=545;
146±178)
(n=568;
399±576)
(n=567;
140±249)
(n=565;
160±243)
(n=462;
63±79)
A
A
A
A
A
A
(n=542;
0.8±5.6)
(n=545;
0.1±0.6)
(n=568;
1.0±7.4)
(n=567;
3.1±15.2)
(n=565;
7.3±141)
(n=462;
1.6±8.4)
C
D
D
A
B
CD
(n=542;
94.6±248.3)
(n=545;
42.4±107.0)
(n=568;
32.9±137.4)
(n=567;
205.3±648.
3)
(n=565;
144.0±376.
2)
(n=461;
73.1±223.9)
B
AB
A
B
B
B
(n=542;
9.2±64.5)
(n=545;
26.3±275.0)
(n=568;
43.4±334.2)
(n=567;
4.0±28.0)
(n=565;
2.6±15.4)
(n=462;
3.1±10.9)
•Different letters indicate significantly different mean (Duncan’s multiple comparison test; p<0.05).
™ Synopsis : Seasonal peaks of abundance of
four zooplankton groups
Northern East
China Sea
April/ October,
December
Yellow Sea
Copepoda
East/Japan
Sea
April
Amphipoda
June
October,
December
None
Chaetognatha
August,
October
April
October
August
April
June
Euphausiid
June
Seasonal cycles in zooplankton biomass in three seas
combined (Korean waters) in response to regime shifts
a
Zooplankton biomass (㎎/㎥)
300
ab
bc
200
cd
d
100
a
d
c
ab
ab
b
ab
cd
d
a
d
bc
0
February
April
June
August
October
d
December
M onth
1965~76
1977~89
1990~00
•Different letters indicate significantly different mean (Duncan’s multiple
comparison test; p<0.05).
Seasonal cycles in zooplankton biomass in the
East/Japan Sea in response to regime shifts
200
Zooplankton biomass (㎎/㎥
a
ab
150
b
a
100
a
ab
ab
a
b
b
bc
a
a
50
c
a
c
June
August
October
c
b
0
February
April
December
Month
1965~76
1977~89
1990~00
•Different letters indicate significantly different mean (Duncan’s multiple
comparison test; p<0.05).
Seasonal cycles in zooplankton biomass in the
Northern East China Sea in response to regime shifts
Zooplankton biomass (㎎/㎥)
700
a
600
500
400
300
200
100
0
ab
d
b
February
ab
a
c
b
April
b
b
ab a
June
August
Month
1965~76
1977~89
b
a
a
b
bc
b
October December
1990~00
•Different letters indicate significantly different mean (Duncan’s multiple
comparison test; p<0.05).
Seasonal cycles in zooplankton biomass in the
Yellow Sea in response to regime shifts
600
a
Zooplankton biomass (㎎/㎥)
500
400
b
300
bc
200
100
bc
c
c
0
February
bc
a
b
d
April
1965~76
ab
June
a
a
August
Month
1977~89
a
c
c
cd
ab
O ctober
December
1990~00
•Different letters indicate significantly different mean (Duncan’s multiple
comparison test; p<0.05).
Synopsis : Seasonal peaks of zooplankton
biomass in response to regime shifts
East/Japan Sea
Northern East
China Sea
Yellow Sea
1965~76
February
(weak)
April/ August,
October
(very weak)
August
(weak)
1977~89
February
~October
(no peak)
October
(weak)
August
~October
(weak)
1990~00
February
(weak)
April
(strong)
June
(strong)
Self-Organizing Mapping (U-matrix) with four
zooplankton groups
p
U-matrix
0.16
0.14
0.12
0.1
0.08
0.06
0.04
0.02
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
2 1 1 1 1 1 1 1 1 1 1 1 1 1 1
2 2 2 2 1 1 1 1 1 1 1 1 1 1 1
2 2 2 2 1 1 1 2 1 1 1 1 1 1 1
2 2 2 2 2 2 2 2 2 1 1 1 1 1 1
2 2 2 2 2 2 2 2 2 2 2 2 1 1 1
2 2 2 2 2 2 2 2 2 2 2 2 2 1 1
2 2 2 2 2 2 2 2 2 2 2 2 2 1 1
2 2 2 2 2 2 2 2 2 2 2 2 2 2 2
2 2 2 2 2 2 2 2 2 2 2 2 2 2 2
1 1 1 1 1 1 6 6 6 6 6 6 6 6 6
1 1 1 1 1 1 6 6 6 6 6 6 6 6 6
1 1 1 1 1 1 6 6 6 6 6 6 6 6 6
1 1 1 1 1 1 6 6 6 6 6 6 6 6 6
1 1 1 1 1 1 6 6 6 6 6 6 6 6 6
1 1 1 1 8 8 8 8 8 6 6 6 10 10 10
1 1 1 1 8 8 8 8 8 6 6 10 10 10 10
8 8 8 8 8 8 8 8 6 6 10 10 10 10 10
8 8 8 8 8 8 8 4 4 6 6 10 10 10 10
8 8 8 8 4 4 4 4 9 9 9 9 10 10 10
8 8 4 4 4 4 4 4 9 9 9 9 9 10 10
2 4 4 4 4 4 4 4 9 9 9 9 10 10 10
2 2 2 2 4 4 4 4 9 9 9 9 10 10 10
2 2 2 2 4 4 4 5 9 9 9 10 10 8 8
2 2 2 2 2 5 5 5 5 9 9 10 10 8 8
2 2 3 2 5 5 5 5 7 7 7 7 8 8 8
3 3 3 3 2 5 5 5 7 7 7 7 7 8 8
3 3 3 2 5 5 5 5 7 7 7 7 7 8 8
3 3 3 3 3 5 5 5 7 7 7 7 7 7 7
3 3 3 3 5 5 5 7 7 7 7 7 7 7 7
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
2 1 1 1 1 1 1 1 1 1 1 1 1 1 1
2 2 2 2 1 1 1 1 1 1 1 1 1 1 1
2 2 2 2 1 1 1 3 1 1 1 1 1 1 1
2 2 2 2 2 3 3 3 3 1 1 1 1 1 1
2 2 2 2 3 3 3 3 3 3 3 3 1 1 1
2 2 2 2 2 3 3 3 3 3 3 3 3 1 1
2 2 2 2 3 3 3 3 3 3 3 3 3 1 1
2 2 2 2 2 3 3 3 3 3 3 3 3 3 3
2 2 2 2 3 3 3 3 3 3 3 3 3 3 3
1 1 1 1 1 1 7 7 7 7 7 13 13 13 13
1 1 1 1 1 1 7 7 7 7 7 13 13 13 13
1 1 1 1 1 1 7 7 7 7 7 7 13 13 13
1 1 1 1 1 1 7 7 7 7 7 7 7 7 7
1 1 1 1 1 1 7 7 7 7 7 7 7 7 7
1 1 1 1 8 8 8 8 8 7 7 7 11 11 11
1 1 1 1 8 8 8 8 8 7 7 11 11 11 11
8 8 8 8 8 8 8 8 7 7 11 11 11 14 14
8 8 8 8 8 8 8 3 3 7 7 11 11 14 14
8 8 8 8 3 3 3 3 10 10 10 10 14 14 14
8 8 3 3 3 3 3 3 10 10 10 10 10 14 14
12 3 3 3 3 3 3 3 10 10 10 10 11 14 14
12 12 12 12 3 3 3 3 10 10 10 10 11 11 11
12 12 12 12 3 3 3 5 10 10 10 11 11 15 15
12 12 12 12 12 5 5 5 5 10 10 11 11 15 15
12 12 4 12 5 5 5 5 9 9 9 9 15 15 15
2 2 4 4 12 5 5 5 9 9 9 9 9 15 15
2 2 4 12 5 6 6 6 9 9 9 9 9 15 15
2 2 4 4 4 6 6 6 9 9 9 9 9 16 16
2 2 4 4 6 6 6 9 9 9 9 9 16 16 16
1 1 1 1 1 1 2 2 2 2 2 2 2 2 2
1 1 1 1 1 1 2 2 2 2 2 2 2 2 2
1 1 1 1 1 1 2 2 2 2 2 2 2 2 2
1 1 1 1 1 1 2 2 2 2 2 2 2 2 2
1 1 1 1 1 1 2 2 2 2 2 2 2 2 2
1 1 1 1 2 2 2 2 2 2 2 2 5 5 5
1 1 1 1 2 2 2 2 2 2 2 5 5 5 5
2 2 2 2 2 2 2 2 2 2 5 5 5 5 5
2 2 2 2 2 2 2 2 2 2 2 5 5 5 5
2 2 2 2 2 2 2 2 5 5 5 5 5 5 5
2 2 2 2 2 2 2 2 5 5 5 5 5 5 5
3 2 2 2 2 2 2 2 5 5 5 5 5 5 5
3 3 3 3 2 2 2 2 5 5 5 5 5 5 5
3 3 3 3 2 2 2 4 5 5 5 5 5 2 2
3 3 3 3 3 4 4 4 4 5 5 5 5 2 2
3 3 3 3 4 4 4 4 4 4 4 4 2 2 2
3 3 3 3 3 4 4 4 4 4 4 4 4 2 2
3 3 3 3 4 4 4 4 4 4 4 4 4 2 2
3 3 3 3 3 4 4 4 4 4 4 4 4 4 4
3 3 3 3 4 4 4 4 4 4 4 4 4 4 4
1 1 1 1 1 1 5 5 5 5 5 5 5 5 5
1 1 1 1 1 1 5 5 5 5 5 5 5 5 5
1 1 1 1 1 1 5 5 5 5 5 5 5 5 5
1 1 1 1 1 1 5 5 5 5 5 5 5 5 5
1 1 1 1 1 1 5 5 5 5 5 5 5 5 5
1 1 1 1 2 2 2 2 2 5 5 5 7 7 7
1 1 1 1 2 2 2 2 2 5 5 7 7 7 7
2 2 2 2 2 2 2 2 5 5 7 7 7 7 7
2 2 2 2 2 2 2 2 2 5 5 7 7 7 7
2 2 2 2 2 2 2 2 7 7 7 7 7 7 7
2 2 2 2 2 2 2 2 7 7 7 7 7 7 7
3 2 2 2 2 2 2 2 7 7 7 7 7 7 7
3 3 3 3 2 2 2 2 7 7 7 7 7 7 7
3 3 3 3 2 2 2 4 7 7 7 7 7 2 2
3 3 3 3 3 4 4 4 4 7 7 7 7 2 2
3 3 3 3 4 4 4 4 6 6 6 6 2 2 2
3 3 3 3 3 4 4 4 6 6 6 6 6 2 2
3 3 3 3 4 4 4 4 6 6 6 6 6 2 2
3 3 3 3 3 4 4 4 6 6 6 6 6 6 6
3 3 3 3 4 4 4 6 6 6 6 6 6 6 6
Clusters, SOM map, Ward algorithm
2
2 clusters
1.5
3 clusters
1
0.5
0
181
183
162
184
164
165
185
142
161
163
121
123
122
141
143
124
125
144
145
168
188
187
207
189
209
186
245
205
225
206
265
226
285
182
201
203
202
223
204
224
244
264
284
221
222
243
241
242
263
283
261
262
281
282
28
29
10
30
811
931
48
49
68
88
69
106
89
107
50
108
70
86
128
87
109
129
126
146
127
147
148
166
167
256
277
276
296
297
274
294
275
295
278
298
32
51
52
71
113
72
92
110
93
94
111
90
112
131
130
91
149
150
169
114
133
134
153
132
151
152
170
171
190
191
210
231
232
230
251
172
173
174
193
194
213
192
212
211
195
215
214
233
208
227
228
229
249
246
247
248
266
286
267
287
234
235
254
255
252
253
273
293
250
271
272
292
270
291
290
268
288
269
289
21
23
122
241
325
427
524
43
642
61
44
763
26
45
64
65
46
47
66
101
67
103
62
102
81
82
83
104
105
84
85
12
13
33
14
15
35
16
36
34
55
53
54
73
74
75
76
95
78
97
17
37
18
38
19
39
20
40
56
77
57
58
59
60
79
115
80
116
99
135
96
117
136
137
98
157
154
155
156
175
100
119
120
140
139
118
138
158
159
160
179
180
200
199
219
176
177
196
197
178
198
216
217
218
236
237
238
257
258
220
239
240
259
260
279
280
300
299
Classification of clusters by the SOM map
5 clusters
7 clusters
10 clusters
16 clusters
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
2 1 1 1 1 1 1 1 1 1 1 1 1 1 1
2 2 2 2 1 1 1 1 1 1 1 1 1 1 1
2 2 2 2 1 1 1 3 1 1 1 1 1 1 1
2 2 2 2 2 3 3 3 3 1 1 1 1 1 1
2 2 2 2 3 3 3 3 3 3 3 3 1 1 1
2 2 2 2 2 3 3 3 3 3 3 3 3 1 1
2 2 2 2 3 3 3 3 3 3 3 3 3 1 1
2 2 2 2 2 3 3 3 3 3 3 3 3 3 3
2 2 2 2 3 3 3 3 3 3 3 3 3 3 3
Cluster
Cluster I
Cluster II Cluster III
Copepoda
Low
Middle
High
Amphipoda
Middle
Low
High
Chaetognatha
Low
High
Low
Euphausiid
Low
Low
High
Cluster
Cluster
Cluster
Frequency of sites for Cluster I
Month
East/Japan Sea
Northern East
China Sea
Yellow Sea
1st period (1978~89)
2nd period (1990~00)
February
339 (97.7 %)
237(85.3%)
April
348 (98.0% )
195(67.2%)
June
314(89.7%)
225(78.7%)
August
318 (86.9%)
188(63.5%)
October
349 (93.1%)
149(55.0%)
December
366 (97.3%)
203(70.0%)
February
231 (97.5%)
125(82.2%)
April
223 (92.5%)
93(51.1%)
June
214 (88.8%)
102(62.6%)
August
204 (91.1%)
99(57.6%)
October
198 (85.3%)
84(42.9%)
December
204 (93.6%)
122(72.2%)
February
156 (60.2%)
88(34.4%)
April
132 (47.1%)
90(30.8%)
June
149 (49.5%)
81(28.6%)
August
164 (55.4%)
70(24.3%)
October
138 (45.8%)
56(18.3%)
December
163 (57.8%)
73(36.1%)
* % indicates sampling site frequency in each cluster over total sampling sites.
Frequency of sites for Cluster II
Month
East/Japan Sea
Northern East
China Sea
Yellow Sea
1st period (1978~89)
2nd period (1990~00)
3 (0.9%)
2(0.7%)
April
0(0%)
1(0.3%)
June
2(0.6%)
2(0.7%)
August
8(2.2%)
12(4.1%)
October
8(2.1%)
8(3.0%)
December
1(0.3%)
6(2.1%)
February
2(0.8%)
2(1.3%)
April
0(0%)
1(0.5%)
June
1(0.4%)
4(2.5%)
August
2(0.9%)
21(12.2%)
October
12(5.2%)
16(8.2%)
December
8(3.7%)
2(1.2%)
February
81(31.3%)
137(53.5%)
April
94(33.6%)
99(33.9%)
June
64(21.3%)
71(25.1%)
August
96(32.4%)
176(61.1%)
October
109(36.2%)
203(66.3%)
December
86(30.5%)
88(43.6%)
February
* % indicates sampling site frequency in each cluster over total sampling sites.
Frequency of sites for Cluster III
Month
East/Japan Sea
Northern East
China Sea
Yellow Sea
1st period (1978~89)
2nd period (1990~00)
February
5(1.4%)
39(14.0%)
April
7(2.0%)
94(32.4%)
June
34(9.7%)
59(20.6%)
August
40(10.9%)
96(32.4%)
October
18(4.8%)
114(42.1%)
December
9(2.4%)
81(27.9%)
February
4(1.7%)
25(16.4%)
April
18(7.5%)
88(48.4%)
June
26(10.8%)
57(35.0%)
August
18(8.0%)
52(30.2%)
October
22(9.5%)
96(49.0%)
December
6(2.8%)
45(26.6%)
February
22(8.5%)
31(12.1%)
April
54(19.3%)
103(35.3%)
June
88(29.2%)
131(46.3%)
August
36(12.2%)
42(14.6%)
October
54(17.9%)
47(15.4%)
December
33(11.7%)
41(20.3%)
* % indicates sampling site frequency in each cluster over total sampling sites.
Conclusion
V In the Korean waters, there are two peaks in
zooplankton biomass, a large peak in April and
a small peak in October
– There are differences in peak time according to
seas : February in the East/Japan Sea, April in the
Northern East China Sea and June in the Yellow
Sea.
V After 1989 regime shift, seasonal cycles was
more clear, and seasonal peak appeared early.