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THE REACTION OF THE BLACK SEA B. IMPROVISUS DARWIN TO REDUCED SALINITIES (Otnoshenie Chernomorskogo Usonogogo Rachka Balanus Improvisus Darwin K Usloviyam Ponizhennoi Solonesti)

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Experimental investigations in the tolerance of the Black Sea Balanus improvisus to reduced salinities show that the individuals of the species taken from waters having the salinity of 18 are capable of enduring an extremely great dilution of water. Observations on the growth, the rate of oxygen consumption, and on spawning of B. improvisus disclose that the salinity range from 18 to 5 is tolerated by the animals in all stages of development and that they are capable of reproduction. With the reduction in salinity to 3 and less, the greater part of the barnacles die in a few months and none of them are capable of reproduction. It was further found that barnacles need a certain time for adapting themselves to the new salinity concentrations, the period becoming longer with lower salinity concentrations. The adaptation is most clearly pronounced in the growth of barnacles. At lower salinities the growth rate decreases only for a limited time period after which it surpasses the usual speed and the barnacles reach a larger size than those living in salinity conditions that are normal to them. As a result, the former become capable of enduring greater salinity reductions for a longer time than other barnacles. Because of the pronounced ability of adaptation, the Black Sea barnacle has spread into the Sea of Azov, where the average salinity concentration is 11 and, traveling by vessels, is gradually penetrating into the diluted areas of gulfs and estuaries in this sea and infesting the coastal structures.

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  • Biological Oceanography

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