Zooplankton of the open Baltic: Extended Atlas - IOW

5000µm net
1000µm net
200µm net
Bottle sampler
5000 µm
5000 µm
1000 µm
1000 µm
> 5000 µm
200 µm
GF-F filter
200 µm
200 - 1000 µm
1000 - 5000 µm
0,.. - 200 µm
Sum: Total plankton
Figure 3.2.2. Scheme for eliminating the overlapping upper size
fractions from samples collected with different mesh sizes. Ideally, the sum
should be the total amount of plankton (UNESCO, 1968).
If several laboratories contribute to a joint data bank, standard operation
procedures for sampling and analysing techniques are required to be used in
each. For the HELCOM Monitoring and Assessment programme, a vertical
sampling is recommended considering the actual hydrographic stratification.
The amount of filtered water should be determined by a flow meter.
These instruments should optimally work within the towing velocity used. For
example, the T.S.K. flow meter (The Tsurumi-Seiki Co., Ltd., Yokohama,
Japan) is suitable for the WP-2 net. It should be placed in the half of radius. It
is the position which provides nearly 100% filtration efficiency (Fig. 3.2.3).
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