Spatio-temporal changes of macrophytobenthos in coastal landscapes at Cape Kosa Severnaya (Sevastopol)

Using a landscape approach, the paper presents for the first time the results of a comparative analysis of spatio-temporal changes in the macrophytobenthos, performed at Cape Kosa Severnaya for the period from 1964 to 2020 with landscape maps compiled by the authors. In addition, it describes the distribution of the bottom natural complexes (BNC) with key Black Sea phytocoenoses (Ericaria crinita, Gongolaria barbata i Phyllophora crispa). It was found that during this period a dramatic increase in the biomass of the phytocoenosiswas recorded in the BNC block-boulder bench with dominance of E. crinita, while the proportion of its edificator remained high. The maximum contribution of epiphytic sinusia to biomass of algocoenosis over the entire study period was recorded in 2006. For the BNC up-per shoreface slope consisting of coarse-grained deposits with dominance of E. crinita i G. barbata, an increase in phytocoenosis biomass was recorded only at the upper boundary during the study period. For the BNC of gently dip-ping accumulation plain consisting gravel-psammitic sediments with inclusion of shell fragments and dominance of Phyllophora crispa, a catastrophic decline in the productivity of the phytocenosis and its edificator is typical. The total biomass of macrophytes decreased by more than an order of magnitude during the study period. It was found that over a span of 50 years, the plant components of bottom natural complexes at Cape Kosa Severnaya underwent significant restructuring and degradation due to natural factors and anthropogenic activity in the coastal zone. The high degree of preservation of indigenous phytocenoses, the presence of red book species (P. crispa and Stilophora tenella) allow us to recommend the site at the Cape Kosa Severnaya as a promising reserve.