이매패류 어미관리를 위한 미세조류 기반 폐쇄-순환여과시스템 개발 연구

Techniques were developed for holding and conditioning of Pacific oysters, Crassostrea gigas, in a closed recirculating system. Experimental adults were used 500 oysters ( x two system, total 1,000 oysters) which were collected in 20 th March 2016 from long-line aquaculture farm at the south coast of Korea. During conditioning periods concentrated live microalgae as Isochrysis sp. 15 × 10 7 cells/mL, Tetraselmis sp. 2 × 10 7 cells/mL and Pheaodactylum sp. 18 × 10 7 cells/mL were added 5 L every day, respectively which micro algae were functioned as diets and biological filter. Over all experimental periods total water exchange rate was 21.3% (daily 0.5%). Over 42 days conditioning, female and male oysters were maturated 90.9% and 94.4%, respectively. Survival rate was 98.7%. Mean shell hight (8.3 ㎜), total wet weight (19.2 g), meat wet weight (5.0 g) and shell wet weight (13.6 g) were significantly increased (P＜ 0.05). Water quality parameters including the water temperature (22.1 ± 0.4℃), salinity (24.9 ± 04), dissolved oxygen (5.1-7.9 ㎎/L) and pH (7.93 ± 0.15) were kept stable. Concentration of dissolved inorganic nutrient as ammonia (1.96-0.35 ㎎/L), nitrite (0.03-0.16 ㎎/L), nitrate (1.34-0.47 ㎎/L), DIP (0.42-0.03 ㎎/L) and silicate (3.83-0.00 ㎎/L) were significantly decreased throughout experiment except nitrite which was increased (P＜ 0.05), but nitrogenous components stayed below toxic levels (ammonia 0.0-5.5 ㎎/L, nitrite 0.0-460.0 ㎎/L) which indicated that closed recirculation system with microalgae based bio-filter could supply sufficiently environment condition to holding and conditioning of oyster.