Lebedovskaya M. "Microbiological and parasitological aspects of cultivation biotechnology of giant oyster (Crassostrea gigas) in the Black Sea"

Complex microbiological and parasitological study of the giant oyster, which is cultured along the Crimean coast, was carried out in the present work for the first time. It was determined that a high bacterial contamination of seawater (1000 KOE per ml-1) results in a decrease of larva rate of giant oyster grown in controlled environment, as the bacterial contamination acts as a stress factor for the growing larva. A dependency of the number of settled spat on the presence of the Black Sea early stages fouling community on substrate was revealed. The greatest quantity of settled larva (95 oysters/m2) was found on substrate with two week old bacterial pellicle. A level of bacterial seeding of mantle liquid and inner organs of the giant oyster while growing in natural conditions was estimated. It was shown that the level of bacterial seeding of oysters increases with their age and substantially depends on bacterial contamination of the surrounding environment and water temperature. Fauna of Polychaetes in the biotope, which is formed by cultivated in the Black Sea Kazachya bay giant oyster, was studied for the first time. It was represented by 26 species of 14 families, among which Spionidae and Eunicidae are pathogenic to oysters. Polychaete from family Spionidae, Polydora websteri, which is new species for Ukraine's fauna, had been found. The polydoras were found in the giant oysters aged 1 year and older. An occurrence and intensity of affection increase with age of oyster. It was determined that occupancy of cultivated in the Black Sea C. gigas by boring sponge Pione vastifica grows with age of oyster too. A possibility for the 1-year old oyster to be affected by Pione was shown. It is determined that microbiological seeding of pion-affected oysters is 10-100 times higher then that of a healthy shellfish. A study of catalase activity and lypid hydroperoxides in the tissue of adult specimens of the giant oyster when they normal function and being affected by the P. vastifica was carried out for the first time. An increase of catalase activity and hydroperoxide products content in the tissue of oysters, which were affected by the boring sponge, as compared to the healthy shellfish was observed. The obtained results had been successfully tested when the oyster farming in the Ukrainian Armed Forces' scientific research centre "State marine aquarium" was organizing.