Manual for Marine Monitoring in the
COMBINE
Programme of HELCOM
Part C
Programme for monitoring
of eutrophication
and its effects
Annex C-7
Mesozooplankton
ANNEX C-7 MESOZOOPLANKTON
1. Introduction ............................................................................................................................................... 1
2. Purposes..................................................................................................................................................... 1
3. Sampling..................................................................................................................................................... 1
4. Preservation ............................................................................................................................................... 4
5. Sub-sampling.............................................................................................................................................. 4
6. Analysis ...................................................................................................................................................... 5
6.1. Abundance .......................................................................................................................................... 5
6.2 Biomass ................................................................................................................................................ 8
7. Data reporting ............................................................................................................................................ 8
8. Quality Assurance ...................................................................................................................................... 8
References ..................................................................................................................................................... 8
HELCOM COMBINE
Annex C-7 Mesozooplankton
1. Introduction
1. INTRODUCTION
The mesozooplankton (0.2-20 mm) constitutes an important part of the pelagic food web, since they form
the link between primary producers and higher trophic levels. Changes in phytoplankton biomass and
species/size composition change mesozooplankton community structure and productivity. Such changes
potentially influence fish stock recruitment and sedimentation (i.e. oxygen concentration in the bottom
water).
2. PURPOSES
The sampling of mesozooplankton serves, inter alia, the following purposes:
•
to describe the species composition and the spatial distribution of mesozooplankton abundance
and biomass;
•
to describe temporal trends (i.e. over several years) in mesozooplankton biomass and community
structure.
3. SAMPLING
Mesozooplankton should be sampled by means of vertical hauls using a WP-2 net of 100 µm mesh size. The
WP-2 net should be hauled vertically with a speed of about 0.5 m/s.
The nets should always be equipped with flowmeters. They should be mounted at 1/4 of the diameter of
the ring (UNESCO 1968). If the filtration capacity of the net is lower than 70% the sample should be
discarded and a new sample taken after the rinsing of the net.
The weight to keep the wire vertical should be 25 kg (40 kg when the wire angle tends to exceed 25º,
UNESCO, 1968).
The wire angle should always be reported. A correction table for sampling depth is given in Table C.7.1. If
the wire angle exceeds 40º, the sample should be discarded. Records of wind speed should be kept.
For fractionated hauls the following intervals should be considered (Fig. C.7.1):
•
bottom to halocline (included)
•
top of halocline to thermocline (included)
•
top of thermocline to surface
If there is no thermocline, a standard haul of 25-0 m should be made.
If there is no halocline, there should be a standard haul of 75 m to the thermocline (included) or to 25 m if
there is no thermocline either.
Annex C-7 Mesozooplankton
3. Sampling
HELCOM COMBINE
If an anoxic bottom layer is present, sampling should be conducted above the anoxic zone.
No hauls shorter than 5 meters should be made.
In the Kattegatt and Belt Sea a standard haul of 25-0m should be made.
After collection of each sample the net shall always be rinsed by use of a gentle flow from a hose. When
fractionated hauls are taken, only the part below the strap should be rinsed. After emptying, the whole net
shall be rinsed with the cod-end open.
After each cruise, the net shall be washed in warm freshwater with a detergent to secure optimum
filtration capacity.
When jelly-fish appear in the sample, it is recommended to discard the sample and take a new. When it is
impossible to avoid jelly-fish, they should be rinsed from other mesozooplankton and then discarded.
When applicable, these procedures should be recorded.
Table C-7.1. Correction of depth from wire angle
depth z1
wire angle
(m)
5°
10°
15°
20°
25°
30°
5
5
5
5
5
6
6
10
10
10
10
11
11
12
15
15
15
16
16
17
17
20
20
20
21
21
22
23
25
25
25
26
27
28
29
30
30
30
31
32
33
35
35
35
36
36
37
39
40
40
40
41
41
43
44
46
45
45
46
47
48
50
52
50
50
51
52
53
55
58
55
55
56
57
59
61
64
Annex C-7 Mesozooplankton
3. Sampling
HELCOM COMBINE
depth z1
wire angle
60
60
61
62
64
66
69
65
65
66
67
69
72
75
70
70
71
72
74
77
81
75
75
76
78
80
83
87
80
80
81
83
85
88
92
85
85
86
88
90
94
98
90
90
91
93
96
99
104
95
95
96
98
101
105
110
100
100
102
104
106
110
115
110
110
112
114
117
121
127
120
120
122
124
128
132
139
130
130
132
135
138
143
150
140
141
142
145
149
154
162
150
151
152
155
160
166
173
160
161
162
166
170
177
185
170
171
173
176
181
188
196
180
181
183
186
192
199
208
190
191
193
197
202
210
219
200
202
203
207
213
221
231
Figure C-7.1.
HELCOM COMBINE
e. g.
haul 1:
Annex C-7 Mesozooplankton
4. Preservation
5 – 61 m
haul 2: 61 – 30 m
haul 3:
30 – 0 m
4. PRESERVATION
The samples should be preserved in 4% formaldehyde solution (1 part 40% formaldehyde solution and 9
parts water). The formaldehyde has to be buffered to pH 8-8.2 with disodiumtetraborate (borax) (Na2B403 .
10 H20). The samples should be stored until the subsequent assessment is completed.
5. SUB-SAMPLING
A calibrated Stempel-pipette or a Kott Splitter is recommended. The Kott Splitter is somewhat better in
precision but is more time-consuming to handle ( G. Behrends, A. Korshenko, pers.comm.).
For the work with Stempel-pipette the sample is concentrated by sieving or diluted with tap water as
necessary. The volume of the sample is measured in a graduated glass/plastic ware.
A few drops of a detergent should be added to allow the cladocerans to mix in the sample
Annex C-7 Mesozooplankton
6. Analysis
HELCOM COMBINE
The sample should be mixed intensively until all organisms are distributed randomly in the sample volume.
Non-random distribution in the sample during sub-sampling is the most important source of errors.
Aggregations of organisms should be taken out of the sample and the organisms counted.
6. ANALYSIS
The microscopes used should have magnifications to at least 125 X.
6.1. ABUNDANCE
All specimen should be identified and counted until one has reached 100 individuals of each of the three
dominating taxonomic groups (excluding nauplii, rotifers and tintinnids). If this figure is not reached in one
subsample, additional subsamples must be counted. The taxonomic group(-s) that reached 100 individuals
in the previous subsamples, need not be counted in the next subsample(-s). The precision of calculated
abundance for organisms of the first three groups, that will be counted up to 100 specimens, amounts to
20% (Tables C-7.1 and C-7.2). The estimation of abundance for other groups ("tail") will be less precise
(Cassie 1971, HELCOM 1988).
The term "taxonomic groups" includes species, genera, families and different developmental stages of
copepods.
The abundance of nauplii, rotifers, tintinnids and meroplankton larvae can be estimated semiquantitatively from the first subsample. The presence of macrozooplankton organisms and rare species can
be noted after an overview of the whole sample.
Although macrozooplankton, nauplii, rotifers and tintinnids fall outside the size range of mesozooplankton,
as do many of the meroplankton, there is a considerable amount of historic data on these groups. Thus
they could be reported.
Table C-7.2. Lower and upper 95% confidence limits (in units and as a percentage) for number of counting
specimens lower than 17 [4]
N ind
counted
Lower
limit
Upper
limit
Lower limit
(%)
Upper limit
(%)
0
0
3.7
!!!
!!!
1
0.03
5.6
97
460
2
0.2
7.2
90
260
Annex C-7 Mesozooplankton
6. Analysis
HELCOM COMBINE
N ind
counted
Lower
limit
Upper
limit
Lower limit
(%)
Upper limit
(%)
3
0.6
8.7
80
190
4
1.1
10.2
72.5
155
5
1.6
11.8
68
136
6
2.2
13
63.3
116.7
7
2.8
14.4
60
105.7
8
3.4
15.7
57.5
96.3
9
4.1
17
54.4
88.9
10
4.8
18.3
52
83
11
5.5
19.6
50
78.2
12
6.2
21
48.3
75
13
6.9
22.2
46.9
70.8
14
7.6
23
45.7
64.3
15
8.4
24.7
44
64.7
16
9.1
25.3
43.1
58.1
Table C-7.3. Lower and upper 95% confidence limits (in units and as a percentage) for number of counting
specimens more than 17 (see also [2, 3, 4])
N ind
counted
Lower
limit
Upper
limit
Lower limit
(%)
Upper limit
(%)
17
8.9
25.1
47.5
47.5
18
9.7
26.3
46.2
46.2
19
10.5
27.5
45
45
20
11.2
28.8
43.8
43.8
25
15.2
34.8
39.2
39.2
30
19.3
40.7
35.8
35.8
35
23.4
46.6
33.1
33.1
Annex C-7 Mesozooplankton
6. Analysis
HELCOM COMBINE
N ind
counted
Lower
limit
Upper
limit
Lower limit
(%)
Upper limit
(%)
40
27.6
52.4
31
31
45
31.9
58.1
29.2
29.2
50
36.1
63.9
27.7
27.7
60
44.8
75.2
25.3
25.3
70
53.6
86.4
23.4
23.4
80
62.5
97.5
21.9
21.9
90
71.4
108.6
20.7
20.7
100
80.4
119.6
19.6
19.6
110
89.4
130.6
18.7
18.7
120
98.5
141.5
17.9
17.9
130
107.7
152.3
17.2
17.2
140
116.8
163.2
16.6
16.6
150
126
174
16
16
275
242.5
307.5
11.8
11.8
300
266.1
333.9
11.3
11.3
350
313.3
386.7
10.5
10.5
400
360.8
439.2
9.8
9.8
450
408.4
491.6
9.2
9.2
500
456.2
543.8
8.8
8.8
600
552
648
8
8
700
648.1
751.9
7.4
7.4
800
744.6
855.4
6.9
6.9
900
841.2
958.8
6.5
6.5
1000
938
1062
6.2
6.2
1500
1424.1
1575.9
5.1
5.1
HELCOM COMBINE
Annex C-7 Mesozooplankton
7. Data reporting
6.2 BIOMASS
The biomass factors for the different taxonomic groups and developmental stages should be used
(Hernroth, 1985). The method of Standard Size Classes (Witek Z., G. Breuel, M. Wolska-Pyś, P. Gruszka, A.
Krajewska-Sołtys, L. Ejsymont, D. Sujak 1996. Comparison of different methods of Baltic zooplankton
biomass estimations. Proceedings of the XII BMB Sympozjum, Institute of Aquatic Ecology, University of
Latvia: 87-92)** should be used if appropriate factor is missing. The improvement of present factors taking
into account the seasonal and geographical differences in individual volume is an urgent QA task.
Direct measurements of ash free dry weight (AFDW) of ½ sample should be used. Samples, which have
been deep frozen (- 18 C) on pre-weighted glass fibre filters (Whatman GF / C, d = 47 mm), should be dried
at 60 C in an oven (Lovegrove, 1962, 1966) and ashed at 500 C.
**Reference to Standard Size Classess has been added instead of reference to table C.7.2. which is not
available.
7. DATA REPORTING
Data should be reported according to ICES data reporting formats.
8. QUALITY ASSURANCE
[The quality assurance instructions should be according to the recommendations given in the SGQAB
Report of 1998, section 10, part B. This work should be done by the BMB Zooplankton Working Group.
Additional items that should be included:
•
participation in ring - tests;
•
intercalibration of equipment;
•
participation in scientific workshops when e.g. recent taxonomical changes can be implemented.]
REFERENCES
Cassie, R.M. 1971. Sampling and statistics. In: A manual on methods for the assessment of secondary
productivity in fresh water. Ed. By W.T. Edmondson and G.G. Winberg. IBP Handbook No. 17, Oxford, 181
pp.
HELCOM 1988. Guidelines for the Baltic Monitoring Programme for the Third Stage. Part D. Biological
Determinands. Balt. Sea Environ. Proc. No. 27D, 161 pp.
HELCOM COMBINE
Annex C-7 Mesozooplankton
References
Hernroth, L. 1985. Recommendations on methods for marine biological studies in the Baltic Sea.
Mesozooplankton assessment. BMB Publication No.10: 1-32.
Kozova, O.M. and Melnik, N.G. 1978. Instruction for plankton samples treatment by counting methods.
Eastern Siberia Pravda, Irkutsk, 52 pp. (In Russian).
Lovegrove, T. 1962. The effect of various factors on dry weight values. Rapp.P.-v.Reun. Cons. int. Explor.
Mer 153, 86-91
Lovegrove, T. 1966. The determination of dry weight of plankton and the effect of various factors on the
values obtained. In: Some contemporary studies in marine science, pp. 462-467. Ed. by H. BARNES. London:
Allen and Unwin Ltd.)
UNESCO, 1968. Monographs on oceanographic methodology. 2. Zooplankton sampling. Paris. 174 pp.
Veldre, S.R. 1961 Statistical verification of counting methods used for quantitative analysis of plankton
samples. In: Application of mathematical methods in biology. Collected papers, Leningrad State University,
Vol. 2: 124-131. (In Russian).