BIOLOGIYA MORYA, 2014, Vol. 40, No. 6, pp. 463-472 |
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Ostracods as indicators of the aquatic environmental conditions on the northeastern Black Sea shelf over the previous 70 years 1A.V. Zhirmunsky Institute of Marine Biology, Far East Branch, Russian Academy of Sciences, Vladivostok 690041; E-mail: ; ; This study deals with ostracod assemblages from the upper part of the Ash-2009-08 mini-core collected from the inner, shallow-water shelf of the northeastern Black Sea off the town of Gelendzhik. The studied part of the core recovered sediments of the last ~70 years. A new ecologo-ethological method is proposed to analyze fossil biotic assemblages that considers the behavioural features of animals along with their ecological preferences. Particular attention is paid to the juvenile/adult ratio of each species; ostracode species are grouped according to the preferred biotopes. This allows us to distinguish autochthonous species generally represented by adult specimens from the species penetrating from nearby biotopes that are mainly or exclusively represented by instars. Five groups were distinguished according to the preferred biotopes: pelobionts, aleurobionts, psammobionts, suprabionts, and stygobionts. The findings of stygobionts in the marine sediments are discussed. Only aleurobionts characterize the environment in situ, whereas the other groups, being stochastic elements, reflect the general diversity of the local fauna. The ostracod assemblages (number of species and their ratio) remained stable during the period studied. Only two intervals of increase in the total ostracod abundance were recorded. A maximum abundance of ostracodes in the 1940s-1960s was caused by eutrophication, while high abundance values in the 1990s are probably associated with the high dynamics of the bottom-waters. Key words: Ostracoda, paleoecology, ecologo-ethological method, stygobionts. |
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