Brown Algae of the Genus Cystoseira in the Sea of Azov: Settling or Expansion of the Range?
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n Algae of the Genus Cystoseira in the Sea of Azov: Settling or Expansion of the Range? O. V. Stepanyan* Federal Research Center, Southern Scientific Center, Russian Academy of Sciences, Rostov-on-Don, 344006 Russia *e-mail: [email protected] Received September 10, 2019; revised April 21, 2020; accepted May 11, 2020
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. Keywords: macroalgae, Black Sea, Sea of Azov, Cystoseira DOI: 10.1134/S2075111720030108
INTRODUCTION In the Black Sea, there are several species of brown algae of the genus Cystoseira, the maximum number (five species) was noted for the Bosphorus–Sinop region of the Turkish coast (Aysel and Erduğan, 1995; Aysel et al., 1996, 2004, 2008). A number of researchers (Shiganova et al., 2012) unequivocally consider the invasion of Mediterranean species of macroalgae, including representatives of the genus Cystoseira, into the Black Sea as an invasion. Two species—Cystoseira barbata and C. crinita—relate to perennial algae and mass species of the upper sublittoral of the Black Sea, which form stable communities—typical biotopes characteristic of the Black and Mediterranean seas (Kalugina-Gutnik, 1975). Both species have a wide ecological plasticity; however, C. crinita prefers depths from 0.5 to 5 m, and C. barbata from 2.0 to 25 m. Since the beginning of the 2000s, a steady tendency toward a decrease in areas and the disapp
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