Net zooplankton


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).

Distribution of stations with net zooplankton samples
Figure 1 - Distribution of stations with net zooplankton samples (2003-2008)

Table 1 - Inventory of stations with net zooplankton samples (2003-2008)
YearMonths
123456789101112Year
Sea of Azov
20032321816
2004421334931176
20057147231153
2006512876543
20081416
Total1602293163121691105194
Black sea
200411
200533
Total0000040000004
Total by seas1602293167121691105198