PRESENT STATE OF FAUNA FREE-LIVING NEMATODES OF THE ODESSA SEA REGION

Abstract

The study is based on the materials of benthic surveys carried out in 2005–2011 years. In Odessa marine region 50 species of free-living nematodes has been found belonging to 5 orders. The nematodes are found in almost all sites and made one of the dominant groups of meiobenthos in occurrence (93.8-100%) and population density (61.1%). Their biomass was 21.3%. Average abundance of nematodes totaled 180.8 ± 33.7 thousands expl.∙m-2 and biomass – 33.22 ± 6.28 mg∙m-2. Maximum density and high number of species (35) was noted on silts (the average abundance 270.0 ± 52.9 thousands expl.∙m-2, average biomass 50.90 ± 10.06 mg∙m-2).Nonselective detritophagous play the main role on all types of soil (35.7-58.0% of nematode population density). Sabatieria pulchra, Sabatieria abyssalis, Terschellingia pontica, Sphaerolaimus ostreae, Viscosia minor, Enoploides brevis are the predominant species. They are characterized by the high stability of its development in the current environmental conditions in the region. Among the constant dominant species in the central and southern parts of the district at a considerable distance from the coast and at depths of 20 m and more S. abyssalis dwelled and made from 37 to 56% of the nematodes abundance. In the coastal zone at depths up to 10 m with a predominance of sandy substrate except S. abyssalis (35% of population abundance), it is of great importance S. pulchra (12-35%). In the Gulf of Odessa near the port on the black silts S. pulchra (24-35%) dominated. The maximum abundance of nematodes observed in summer.The results of these studies can complement understanding of meiobenthos in Odessa marine region and the northwestern part of the Black Sea.