286
Assay of Some Common Hydrobiological Techniques
above technique, involving the use of fine plankton gauze, gives only an
approximate presentation of the abundance of this group, because it underestimates 40-50-f.lm nauplii stuck in the mesh of the net, or small appendicularians and rotifers for which this treatment is too rough. Its adequate
evaluation is possible by only viable count or the filtration technique.
The viable count is the most rapid and practical way of multicellular
microzooplankton quantification in coastal and brackish marine waters and
in lakes where its biomass is usually over 30-40mgm- 3 • For its counts, a
chamber of the kind shown in Fig. 6.6, 5 mm high and 8 x 15 cm in size having
a capacity of about 50cm 3 , might be used. Examination of two or three such
chambers from the same water sample provides the possibility to estimate
biomass as low as 1O-15mgm- 3 quite adequately. In the open sea or in oligotrophic lakes, the filtration procedure for concentrating samples can be used,
selecting one of the following versions (Tumantzeva and Sorokin 1983):
1. Incomplete filtration: 0.5-21 of water is filtered through 1-2-f.lm pore size
membrane filters or at a 5-8-f.lm Nucleopore filter in a funnel of 40mm
inner diameter with a tap on its exit tube (Fig. 4.8). Filtration is stopped
when approximately 3-5 ml of water still remain in the funnel. This remaining water is gently mixed with the aid of a fine brush to resuspend the
precipitate. The suspension is transferred into a beaker, fixed with Lugol
solution, and the microzooplankton in it is counted in a chamber.
2. The water sample is filtered in the same way to the end, the tap on the exit
tube of the funnel is closed, and 1-2ml of a stain solution is added to it.
Some 5-10min later, the tap is opened, the stain solution is filtered down.
The filter is washed from the remains of the stain by rinsing with two or
three portions of water. In this case, 0.5 % erythrosine in 2 % phenol, 0.01 %
aqueous methylene blue or 0.05% aqueous acridine orange can be used as
stain solutions. The wet filters stained with erythrosine or methylene blue
are placed on a glass plate with black lines marked on its surface at 4-mm
intervals. The filter is covered with a square slide and the space between
them is filled with water with the aid of a syringe. This preparation is examined stripe by stripe under the stereomicroscope, thus counting and sizing
the animals. The filters stained with the fluorochrome acridine orange are
placed on a glass plate painted black with scratched lines on its surface,
forming 4-mm stripes between them. This preparation is filled with water
and examined under the epifluorescence microscope at magnification 40-70
in the same way.
6.2 Quantification of Mesozooplankton
The quantification at mesozooplankton is among the most firmly established
spheres of hydrobiological research by traditional methods. Nevertheless,
Assay of Some Common Hydrobiological Techniques
above technique, involving the use of fine plankton gauze, gives only an
approximate presentation of the abundance of this group, because it underestimates 40-50-f.lm nauplii stuck in the mesh of the net, or small appendicularians and rotifers for which this treatment is too rough. Its adequate
evaluation is possible by only viable count or the filtration technique.
The viable count is the most rapid and practical way of multicellular
microzooplankton quantification in coastal and brackish marine waters and
in lakes where its biomass is usually over 30-40mgm- 3 • For its counts, a
chamber of the kind shown in Fig. 6.6, 5 mm high and 8 x 15 cm in size having
a capacity of about 50cm 3 , might be used. Examination of two or three such
chambers from the same water sample provides the possibility to estimate
biomass as low as 1O-15mgm- 3 quite adequately. In the open sea or in oligotrophic lakes, the filtration procedure for concentrating samples can be used,
selecting one of the following versions (Tumantzeva and Sorokin 1983):
1. Incomplete filtration: 0.5-21 of water is filtered through 1-2-f.lm pore size
membrane filters or at a 5-8-f.lm Nucleopore filter in a funnel of 40mm
inner diameter with a tap on its exit tube (Fig. 4.8). Filtration is stopped
when approximately 3-5 ml of water still remain in the funnel. This remaining water is gently mixed with the aid of a fine brush to resuspend the
precipitate. The suspension is transferred into a beaker, fixed with Lugol
solution, and the microzooplankton in it is counted in a chamber.
2. The water sample is filtered in the same way to the end, the tap on the exit
tube of the funnel is closed, and 1-2ml of a stain solution is added to it.
Some 5-10min later, the tap is opened, the stain solution is filtered down.
The filter is washed from the remains of the stain by rinsing with two or
three portions of water. In this case, 0.5 % erythrosine in 2 % phenol, 0.01 %
aqueous methylene blue or 0.05% aqueous acridine orange can be used as
stain solutions. The wet filters stained with erythrosine or methylene blue
are placed on a glass plate with black lines marked on its surface at 4-mm
intervals. The filter is covered with a square slide and the space between
them is filled with water with the aid of a syringe. This preparation is examined stripe by stripe under the stereomicroscope, thus counting and sizing
the animals. The filters stained with the fluorochrome acridine orange are
placed on a glass plate painted black with scratched lines on its surface,
forming 4-mm stripes between them. This preparation is filled with water
and examined under the epifluorescence microscope at magnification 40-70
in the same way.
6.2 Quantification of Mesozooplankton
The quantification at mesozooplankton is among the most firmly established
spheres of hydrobiological research by traditional methods. Nevertheless,