In the first half of the 20th century, there was an extensive biocoenosis of the unattached red algae Phyllophora crispa on the mussel muds of the central section of the Black Sea’s northwestern shelf, which is known as Zernov’s Phyllophora Field (ZPF). At that time, the area of ZPF was approximately 11000 km2. More than a century after the description of ZPF, long-term changes in its phyto- and zoobenthos have been noted. A period of ecological crisis of the Black Sea ecosystem during the second half of the 20th century was destructive for the phytobenthos of ZPF, with the complete degradation of unattached Phyllophora biocoenosis. In contrast, after a sharp decline in the quantitative development of macrozoobenthos of the soft bottoms in the 1970s, its recovery to pre-crisis levels in the 2010s was noted. Despite the difference in the aforementioned phyto- and zoobenthos dynamics, habitat in the 4025 km² area of the botanical sanctuary of national importance “Zernov’s Phyllophora Field” was recognised as Critically Endangered (CR) within the European Red List of Habitats. In this context, the goal of the present study is to clarify the applicability of the CR category to the entire benthic complex of ZPF water area and to assess the current biocoenotic structure and habitat ordination of the zoobenthos on soft bottoms of the ZPF water area in the current conditions of Black Sea de-eutrophication. The obtained results indicate the presence of one biocoenotic complex (Mytilus galloprovincialis) and three subcomplexes in the zoobenthos of ZPF, where the bivalves Mytilaster lineatus, Modiolula phaseolina, as well as Polychaeta are the next most important subcomplex-forming taxa. Throughout all studies of ZPF, relative stability in the biocoenotic representation of the bottom fauna—with the dominance of M. galloprovincialis—has been observed. Due to the current levels of development in both the soft-bottom macrofauna and assemblages of unattached alga Phyllophora, two different habitats were proposed for identification in the water area of the botanical sanctuary. The first habitat – “Aggregations of unattached red algae Phyllophora in the central part of the northwestern shelf of the Black Sea" – was degraded and can be classified as a CR habitat. The second one – “Pontic circalittoral biogenic detritic bottoms with dead or alive mussel beds, shell deposits, with encrusting corallines and attached foliose sciaphilic macroalgae” – represents the soft-bottom biotope and was associated with the biocoenotic complex M. galloprovincialis, proposed for classification as Least Concern. In accordance with three biocoenotic subcomplexes of complex M. galloprovincialis, the spatial position of the three subhabitats was determined on the soft-bottom in the water area of ZPF.
On finding of Monocorophium insidiosum Crawford, 1937 (Amphipoda, Corophiidae) in the coastal waters of Crimea (Black Sea), a new species for this region
