Brown Algae of the Genus Cystoseira in the Sea of Azov: Settling or Expansion of the Range?

Abstract

Currently, the habitats of Cystoseira in the Sea of Azov and Kerch Strait are concentrated in the southern part of the Gulf of Taman on the eastern part of Tuzla, Cape Achillion, and the Kerch Peninsula—between Cape Khroni and Kazantip. It is shown that the main vector of Cystoseira settlement is directed to the southwestern part of the Sea of Azov, which is facilitated by the compensatory bottom current from the Black Sea, which at the entrance to the Sea of Azov from the Kerch Strait deviates to the west. In studies of 2014–2017, Cystoseira barbata was discovered in 2014 in the area of Cape Zyuk (village of Kyrortnoe) and in 2017 at Cape Chagani (village of Zolotoe) in the Kazantipsky Gulf. In expeditions of 2018 in the area of the actual Cape Kazantip, representatives of Cystoseira were not detected. Probably, the findings of Cystoseira at Cape Kazantip can be expected in the near future, but further progression of brown algae will be limited to loose soils. The conditions of the Sea of Azov are an ecological boundary of the range of the genus Cystoseira, and for these algae, pulsation of the range border is characteristic. Factors that cause the expansion of the range of algae of the genus Cystoseira in the Sea of Azov are an increase in salinity, transparency, and temperature of the seawater. The factors causing the narrowing of the Cystoseira range in the Sea of Azov are a decrease in salinity and water transparency and an increase in the number of severe winters with ice. Algae of the genus Cystoseira are good biological indicators for long-term observations of changes in the hydrological regime of the sea. But to consider them invaders in the Sea of Azov is hardly competent.