Detailed zoning of the coastal and shelf areas of marine ecoregions: a case study of the Black Sea

A system of units for detailed zoning is proposed, which reflects the action of three factors responsible for the bionomic diversity of the shallow seabed. The first factor is tectonics, with which the contemporary, recent, inherited evolution of morphostructures is associated. Uplifting controls the formation of hills, coastal cliffs, and abrasion underwater nearshore slopes. Longitudinal coasts are characterized by narrow coastal and shelf areas; as to the transverse ones, a wide abrasion-accumulative terrace is formed there with numerous reefs and banks offshore. Abrasion-sculptural relief forms correspond to biotopes of biocenoses of the rocky bottom. With troughs associated are flat coastal plains, accumulative coasts with a beach, and an accumulative underwater nearshore slope, representing biotopes of biocenoses of the sandy-silty bottom. The size range of continental margin morphostructures includes bionomic counties, districts, and landscapes. The second factor is the change in bionomic conditions with depth, which allows the subdivision of the shelf into three vertical belts: inner (coastal zone), intermediate, and the outer one bordering on the continental slope. The coastal zone, in turn, is subdivided into the supralittoral, littoral and sublittoral. The third one is geographic zonation. The full range of geographic zones appears only on the ocean surface and in the coastal zone of the sea. The main initial unit of zoning of the shallow seabed is the underwater landscape. The landscape does not intersect with the boundaries of other zonation units. It occurs within one morphostructural county, one vertical belt, one geographical zone. The landscapes of the upper belt of the shelf (coastal zone of the sea) are characterized by the greatest diversity. The internal bionomic heterogeneity of landscapes depends on their morphological structure: a system of horizontal subdivision biotopes - facies, landforms and vertical zones, floors, steps. A fragment of the detailed zoning of the northeastern Black Sea morphostructural county is given as an example. Two districts are considered: the first one is the Transverse Coasts of the Southern Margin of the Scythian Plate (from the Kerch Strait to the city of Anapa), and the second one is the Longitudinal Coasts of the Black Sea Margin of the Caucasian Megaanticlinorium (from the town of Anapa to the city of Novorossiysk). In the first district, in the upper belt of the shelf (in the coastal zone of the sea), two landscapes lying in the nemoral zone are identified; in the second belt, one landscape in the subtropical zone is identified. Landscape maps are provided. The accumulation of a database containing information on the detailed zoning of marine ecoregions will make it possible to identify analogue landscapes - bionomic areas with similar characteristics but located in different ecoregions. The applied value of their identification consists in the development of similar measures for their use and conservation.