The sampling of net plankton was performed with a Juday net, which was first used in the Sea of Azov in the late 1930s (Okul, 1940). This net has an opening diameter of 20 cm and a mesh size of 125 μm. While a relatively large mesh size prevents «blocking» of mesh by phytoplankton colonies in the summer period, this also leads to incomplete samples young copepods, copepods nauplius, and rotifers. These groups of zooplankton are counted in microplankton samples. When sampling zooplankton, the entire water column is towed vertically from the bottom to the surface (the Sea of Azov) and the layer of 0-50 m (the Black Sea). The determination of volume filtrated by the net is by the length and the slope angle of a loosened rope. To sample in the shallow water area of the Sea of Azov, the Apstein net is used from time to time with which a definite volume of water is filtrated.
Determination of net plankton abundance is according to standard methods accepted and adopted in the USSR and Russia in the Bogorov’s chamber (Guidelines, 1980). Determining the biomass of zooplankton was determined by linking the length and volume of specimens, which is an acceptable method for some species and groups such as Cladocera, rotifers, and meroplankton (Povazhniy 2009).
The database contains the results of the Sea of Azov net plankton studies. There are fragmented data for the summer period for the Black Sea (Figure 1 č Table 1).
|Sea of Azov|
|Total by seas||16||0||2||29||31||67||12||16||9||11||0||5||198|