International Workshop On Black Sea Benthos
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Материал Contents(Istanbul-Turkey, 2004)Материал Structure of benthic diatoms taxocenes in modern conditions (Crimea, The Black Sea)(Istanbul-Turkey, 2004) Nevrova, E. L.; Revkov, N. K.; Petrov, A. N.The total updated list of benthic diatoms from the Crimean coast, including 409 species and intra-species taxa has been prepared. More than a half (55%) of general floristic richness of the Black Sea benthic diatoms is formed by species of the Crimean coast. 48 new and 21 rare species have been revealed for Crimean coast, five of them were recognized as newly-found for the whole Black Sea and 4 species were new for science. The comparative structural analysis of benthic diatoms taxocenes from two water areas of Crimean coast have been carried out and based on methods of multivariate statistics. Those areas (Laspi and Sevastopol bays) have substantially differed by content of heavy metals and other pollutants in bottom sediments. The features of spatial organization of benthic diatoms habitats have been investigated for both bays. Statistically significant taxocenotic complexes and subcomplex groupings of diatoms were revealed in each of the bay. Development of diatom taxocene in Laspi bay is caused by worsening of optimal environmental conditions from the central part of the bay towards the both more shallow and deep-water zones. The peak of species richness values coincides with 16-20 m depth, and characterizes the middle sublittoral zone that is the most optimal one for diatom algae inhabitation. In Sevastopol bay the level of toxicants’ content in bottom sediments and water depth are the leading abiotic factors influencing on peculiarities of diatom taxocene structure. The differences in the structural pattern can be caused by presence an eurybiontic species and species having the highest parameters of development within the certain biotope at all stations of the investigated water area. Lists of principal species contributing the most input into similarity within taxocenotic complexes of each bay were compounded. Inter-complex differences in taxocenes structure are mostly pronounced and probably caused by different response of discriminating species to a high level of toxicants. Structural differences at sub-complex level are less pronounced and can be conditioned by similar reaction of discriminating species on joint influence of key environmental factors within a certain bay. The most significant discriminating species can also be considered as indicators of the diatom taxocenes condition under comparative assessment of biotopes subjected to miscellaneous anthropogenic load. It is proposed to consider Tabularia tabulata, Amphora proteus and Nitzschia reversa as indicators of conventionally healthy biotopes, whereas Tryblionella punctata, Diploneis smіthіі and Nitzschia sіgma can be considered as indicators of biotopes subjected to persistent technogenic impact.Материал Current state of the zoobenthos at the Crimean shores of the Black Sea(Istanbul-Turkey, 2004) Revkov, N. K.; Sergeeva, N. G.The analysis of current state of zoobenthos at the Crimean shores of the Black Sea is fulfilled. The general features of taxonomical structure, regional peculiarities of bottom fauna development and species number distribution pattern with depth are considered. The results obtained testify the absence of species number reduction at the Crimean coastal zone of the Black Sea over the 2nd half of the XX century. Total number of the macrozoobenthos species registered in the Crimea water area exceeds 560. Filter-feeding mollusks (Chamelea gallina and Modiolula phaseolina first of all) became the most pronounced “evolutioning” species, determining the quantitative changes of the bottom fauna over the soft-bottoms of the southwestern Crimea during the period 1930-s – 1990-s. The shift to lesser depths: from the zone of the mussel silts (26-50 m) to the silty-sand (13-25 m) of the most productive benthal belt of the southwestern Crimea is marked. Meiobenthos (eumeiobenthos) of the Crimean shelf includes more than 522 species in total. Formation of specific meiofauna composition in areas of the methane gas seeping is marked. The presence of 38 species and 6 genera of Nematoda, which are registered only in the given conditions testify to this.