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Species composition of the free living multicellular invertebrate animals (Metazoa: Invertebrata) from the Bulgarian sector of the Black Sea and the coastal brackish basins

Zdravko Hubenov

29 July 2015 · volume 21 · pp. 49–168 · PDF [full text]

Abstract: A total of 19 types, 39 classes, 123 orders, 470 families and 1537 species are known from the Bulgarian Black Sea. They include 1054 species (68.6%) of marine and marine-brackish forms and 508 species (33.0%) of freshwater-brackish, freshwater and terrestrial forms, connected with water. Five types (Nematoda, Rotifera, Annelida, Arthropoda and Mollusca) have a high species richness (over 100 species). Of these, the richest in species are Arthropoda (802 species — 52.2%), Annelida (173 species — 11.2%) and Mollusca (152 species — 9.9%). The remaining 14 types include from 1 to 38 species. There are some well-studied regions (over 200 species recorded): first, the vicinity of Varna (601 species), where investigations continue for more than 100 years. The aquatory of the towns Nesebar, Pomorie, Burgas and Sozopol (220 to 274 species) and the region of Cape Kaliakra (230 species) are well-studied. Of the coastal basins most studied are the lakes Durankulak, Ezerets-Shabla, Beloslav, Varna, Pomorie, Atanasovsko, Burgas, Mandra and the firth of Ropotamo River (up to 100 species known). The vertical distribution has been analyzed for 800 species (75.9%) — marine and marine-brackish forms. The great number of species is found from 0 to 25 m on sand (396 species) and rocky (257 species) bottom. The groups of stenohypo- (52 species — 6.5%), stenoepi- (465 species — 58.1%), meso- (115 species — 14.4%) and eurybathic forms (168 species — 21.0%) are represented. The marine and marine-brackish species are divided into 162 zoogeographical categories, combined into 4 main groups and 16 subgroups. The main portion of the Black Sea fauna has an Atlantic-Mediterranean origin and represents the impoverished Atlantic-Mediterranean fauna (740 species — 70.2%). Cosmopolitan, Atlantic-Indian, Atlantic-Pacific, endemic and Caspian relict forms are represented. The benthic (115 species — 97.5%) and marine (114 species — 96.6%) forms of the Black Sea endemics (118 species — 11.2%) predominate. The brackish endemics (11 species — 9.3%) most often are Caspian relicts. The main portions of the Caspian relicts (41 species — 3.9%) are benthic brackish forms (38 species — 92.7%). The freshwater-brackish, freshwater and terrestrial forms, connected with water, are divided into 80 zoogeographical categories, combined into 2 groups and 5 subgroups. Typical for the coast is the prevalence of the species, distributed in Palaearctic and beyond it (296 species — 58.3%). Species, distributed only in Palaearctic but in more than one subregion (79 species — 15.5%) and species, distributed within one Palaearctic subregion (126 species — 24.8%) are represented — Eurosiberian (55 species — 10.8%) and Mediterranean (71 species — 13.9%). A short characteristic of the planktonic and benthic cenoses is done and some coastal basins are scrutinized. An attention is paid to the invasive immigrants that changed the Black Sea communities during the last 60 years. The species of economic and conservation importance are discussed.

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