Current state of the macrophytobenthos of the Georgian coast

Paper presents first data on seasonal and inter-annual features of macrophytobenthos of the Black Sea coast of Georgia. The study was conducted at four monitoring stations (Sarpi, Cape Zeleny, port Batumi, Tsikhisdziri) in different seasons of 2016–2019. A total of 27 species of macrophytes from the divisions Rhodophyta (13),Chlorophyta (9) and Ochrophyta (5) were identified. Their ecological activity was estimated based on the values of the specific surface of populations. The role of sensitive (S/Wp = 5–25 m2 ∙ m2 ∙ kg-1) and tolerant (S/Wp ≥ 25 m2 ∙ 2 ∙ kg-1) species in relation the quality of the marine environment in the structure benthic communities of macrophytobenthos was analyzed. Of the identified macrophytes, 8 species are classified as sensitive and 19 as tolerant. The largest number of sensitive species was found at Cape Zeleny and Tsihisdziri stations, which indicates a satisfactory ecological condition of these sites. At the Batumi port station, only tolerant species were recorded, which is evidence of a significant anthropogenic load in this area. Representatives of Rhodophyta demonstrated the greatest variability of ecological activity (325%). This allows them inhabit areas with different intensity of the primary production process. A regular relationship between the seasonal dynamics and the absolute values of macrophyte biomass was demonstrated. Communities in satisfactory ecological conditions, with a predominance of sensitive species and high biomass, demonstrate clear seasonal dynamics. The values of macrophyte biomass increase threefold in the spring and summer. Analysis of the year-on-year dynamics of macrophytobenthos along the coast of Georgia showed that 2016 was the most favorable year for macrophytobenthos communities.