꼬막(Tegillarca granosa)의 난 발생 및 유생 발달

Early Developmental Morphology of the Ark Shell, Tegillarca granosa

꼬막, Tegillarca granosa의 인공종묘생산 기술개발을 목적으로 생물학적 기초자료를 얻고자 난 발생 및 유생발달에 미치는 환경조건을 조사하였다. 꼬막의 방출된 알은 70㎛의 분리침성란이었고, 난발생의 최적 환경조건은 수온20-30℃, 염분 30-35psu, pH 7-8로 나타났다. 유생의 최적 사육조건은 수온 25-27℃, 밀도 4-6indiv./㎖, 먹이생물 Isochrysis galbana를 혼합하여 급이 하는 것으로 나타났다. 대량 유생사육은 수온 28℃에서 먹이생물 Isochrysis galbana, Tetraselmis suecica, Phaeodactylum sp., Chaetoceros calcitrans를 혼합하여 1-5×104/㎖로 급이하며 사육하여 24일째에 270㎛로 성장하였다. 난과 유생의 발달은 수온 28℃에서 수정 후 상실기유생(6시간), 담륜자유생(10시간), D형유생(20시간, 90㎛), 초기각정기유생(10일, 120㎛), 중기각정기유생(15일, 160㎛), 후기각정기유생(19일, 180㎛), 침착각 정기유생(24일, 270㎛)으로 성장하였다.

In order to obtain the basic biological information of artificial seedling production on the ark shell, Tegillarca granosa, the early developmental morphology was investigated on environment and rearing conditions. Eggs of the ark shell were demersal and 60 ㎛ in diameter after spawning. Optimum environment conditions (water temperature, salinity, and pH) of egg development, were ranged 20-30 ℃, 30-35 psu, and 7-8, respectively. As for optimum rearing condition on larvae development, water temperature, stocking density, and food organisms were 25-27℃, 4-6 ind./㎖, and the mixture of phytoplanktons (mainly Isochrysis galbana), respectively. On 24 day after fertilization, the larvae grew up to 270 ㎛ in the shell length (SL) when larvae were fed by mixture of phytoplanktons (Isochrysis galbana, Tetraselmis suecica, Phaeodactylum sp., and Chaetoceros calcitrans) in the concentration of 1-5×104 cells/㎖ at 28℃. At 28 ℃, fertilized eggs were developed to morula, trochophore, D-shaped (90 ㎛ SL), early umbo (120 ㎛ SL), middle umbo (160 ㎛ SL), post umbo (180 ㎛ SL), and immension umbo (270 ㎛ SL) stages at 6 hours, 10 hours, 20 hours, 10 days, 15 days, 18 days, and 24 days, respectively.