EXPRESS ESTIMATION OF PLANKTON SIZE FRACTIONS IN THE WATER AREA OF SEVASTOPOL IN WINTER 2021-2022: MODEL STUDIES

Abstract

For the purpose of monitoring the water area of Sevastopol a line of devices for plankton macrofiltration in the size range from 2 mm to 2 microns has been developed. Twelve stations have been chosen from Inkerman to Fiolent with total length of 30 km. From piers far out at sea, 50-500 liters of seawater were sampled from the surface and filtered through a system of successive sieves 2 mm, 300, 150, 84 microns and a 2 μm fiber filter. In the winter of 2021-2022, when the seawater temperature was 8 °C, the diversity of plankton morphotypes was low. For all stations, the number of morphotypes increased as the size fraction decreased in the form of ecological pyramids. It was found that the richness of morphotypes in Inkerman is significantly lower than at other stations. Samples from neighboring stations may differ in the composition of morphotypes up to 50% (spatial section). Also, sea water samples taken at the same station with an interval of 1.5 months differed by 50% in the composition of morphotypes (time slice). The obtained results indicate that the developed technique of sequential filtration gives a visual representation of the state of meso-, micro- and nano-plankton in seawater samples.