Taxonomic analysis of macrophytobenthos in the area of the natural monument "Coastal aquatic complex near cape Fiolent" (Black Sea)

An increase in anthropogenic impact on protected marine objects makes their biodiversity decrease. There is a need to make forecasts of the impact on their coastal zone. The forecasts should be based on the results of long-term observations, which were carried out sporadically in the water area of the natural monument "Coastal aquatic complex near Cape Fiolent" in the middle of the 20th century. Information about the flora of the monument is scarce and needs to be updated. The aim of the study was to investigate the species composition, taxonomic structure and variability of the monument macrophytobenthos in modern conditions. Algological works were carried out by the method of vertical hydro-botanical sections in July 2021. Samples were taken by a diver at depths of 0.5; 1, 3, 5, 10 and 15 m in the eastern and western sections. A list of 90 species, 63 genera, 35 families, 24 orders, 5 classes Chlorophyta, Ochrophyta, Rhodophyta was compiled based on data for the period 1977 - 2021. 13 species have a conservation status. The basis of phytocenosis is formed by minor genera and the floristic spectra - by a limited number of superspecific taxa. In 2021 the phytocenosis of the monument included 52 species. The flora of the monument is warm-water, subtropical, and its habitat is mesotrophic. Comparison of the composition of phytocenoses in the eastern and western sites revealed no fundamental differences. Low values of Jaccard's coefficient indicate bathymetric isolation of the floristic composition. A direct dependence of the number of species on depth was revealed. It is shown that qualitative heterogeneity of phytocenoses in different decades is not as pronounced as within the same decade.