Distribution of Acipenser sturio L., 1758 in the Black Sea and its watershed

The Atlantic sturgeon Acipenser sturio L., 1758, was always rare in the Black Sea, and the least numerous in comparison with other sturgeons. At the end of the 19th and the first half of the 20th centuries, it occurred along almost the entire Black Sea coast. It has been distributed predominantly in the eastern part of the Black Sea, especially in the region adjacent to Georgia's Inguri and Rioni rivers, with spawning grounds in the latter. It has also been recorded occasionally in the Danube River, where it occurred mostly in its delta. Earlier records even indicate its reproduction in the Danube. Recently its distribution and population density has been dramatically reduced. The distribution of this species is limited only to the eastern part of the Black Sea, and the recent total density of adults is estimated at only several hundred specimens. This situation has placed A. sturio on the list of critically endangered fish species. Existing data on its morphology and ecology indicate some differences between the Black Sea stock and populations from the Atlantic Ocean and the Baltic and Mediterranean Seas.El esturión atlántico Acipenser sturio L., 1758 siempre ha sido raro en el mar Negro, y el menos numeroso en comparación con otros esturiones. A finales del siglo XIX y primera mitad del XX se encontraba a lo largo de toda la costa del mar Negro. Se distribuía predominantemente en la parte oriental del mar Negro, en especial en la región adyacente a los ríos Inguri y Rioni en Georgia, con áreas de freza en este último. También ha sido citado ocasionalmente en el río Danubio, donde ocupaba sobre todo su delta. Las citas más antiguas incluso indican su reproducción en el Danubio. Recientemente su distribución y densidad de población se han visto dramáticamente reducidas. La distribución de esta especie se limita sólo a la parte oriental del mar Negro, y la densidad total reciente de adultos se estima en sólo algunos cientos de individuos. Esta situación ha colocado a A. sturio en la lista de especies de peces en peligro crítico. Los datos conocidos sobre su morfología y ecología indican algunas diferencias entre la población del mar Negro y las del océano Atlántico y los mares Báltico y Mediterráneo.Instituto Español de Oceanografí

Nuclear Markers of Danube Sturgeons Hybridization

Acipenseriformes are composed of 25 sturgeon species and two paddlefish species distributed exclusively in the northern hemisphere. The Danube River and the Black Sea were originally inhabited by six sturgeon species but two are extinct and only four are still reproducing currently in the Lower Danube: Huso huso, Acipenser stellatus, A. gueldenstaedtii and A. ruthenus. Sturgeon species hybridize more easily than other fish and the determination of pure species or hybrid status is important for conservation and for breeding in fish farms. This survey demonstrated that morphological determination of this status is not reliable and a molecular tool, based on eight microsatellites genotypes is proposed. This method, based on three successive statistical analyses including Factorial Correspondence Analysis (FCA), Structure assignation and NewHybrids status determination, showed a high efficiency in discriminating pure species specimens from F1, F2 and two kinds of backcross individuals involving three of the four reproducing Lower Danube sturgeon species

Liver, gills, and skin histopathology and heavy metal content of the danube sterlet (acipenser ruthenus linnaeus, 1758)

The sterlet (Acipenser ruthenus L.) is a bottom-feeding fish species with a direct exposure to contaminants from water and sediments. Although heavy metal pollution is believed to be one of the main threats to the sterlet population in the Danube River basin, there is a lack of knowledge of the exact impact of heavy metals on their survival. In the present study, effects of heavy metal pollution on sterlet in the Danube basin were assessed as well as the utility of different sterlet organs and tissues as indicators of heavy metal contamination. The sterlet were sampled at three different sites in the Danube basin, in Hungary and Serbia, isolated from each other by dams. Heavy metal analysis included measurement of Cd, As, Pb, Cr, Hg, Cu, Ni, Fe, Mn, and Zn concentrations in sterlet gills, muscle, liver, and intestine, and histopathological analyses comprised assessment and scoring of the extent and intensity of alterations in skin, gills, and liver tissue. Analysis revealed a significant presence of sublethal histopathological changes that were most pronounced in the liver and skin and increased accumulation of heavy metals, with the highest concentrations in the liver. Canonical discriminant analysis showed significant differentiation among the three studied localities, suggesting that the heavy metal concentrations in sterlet populations were site specific. The present study concludes that the accumulation of heavy metals is a response to the presence of these pollutants in the environment, and, together with other pollutants, it affects the vital organs of natural sterlet populations