养殖密度对毛蚶幼虫生长及存活的影响 [中文引用][英文引用]

为探讨毛蚶(Scapharca subcrenata)幼虫养殖的最佳密度,本研究设定了5个不同的放养密度(2、5、8、14、20 ind/mL),养殖实验从D型幼虫阶段一直持续到幼虫完成附着变态。实验结果表明,随着放养密度的增加,水体氨氮浓度、亚硝酸盐浓度显著升高(P < 0.05);幼虫密度为20 ind/mL时,分别达到最大值0.089 mg/L和0.008 mg/L。溶解氧浓度则随幼虫密度的增大呈现下降的趋势,幼虫密度达到14、20 ind/mL时,显著低于其他密度组(P < 0.05)。幼虫的生长速率随放养密度的增加显著下降, 5~8 ind/mL为幼虫最佳生长密度。幼虫的存活率也随着放养密度的增加显著下降(P < 0.05),当幼虫的放养密度为20 ind/mL时,存活率仅为35%。放养密度为8 ind/mL时,幼虫的附着密度最大,且在附着基下层的附着密度显著高于中层和上层(P < 0.05)。同时,随着放养密度的增加,幼虫附着变态的时间被延长,附着变态规格也显著减小(P < 0.05)。因此,综合考虑各种要素,规模化苗种生产中幼虫的培育密度控制在5~8 ind/mL较为适宜。

We performed experiments at stocking densities of 2, 5, 8, 14, and 20 larvae/mL to determine optimal larval density for hatchery culture of bloody clam, Scapharca subcrenata. Larval developmental stages from D-veliger to settlement and metamorphosis were included. The results indicated that total ammonia nitrogen (TAN) and nitrite increased significantly with increasing stocking density (P < 0.05). TAN and nitrite levels in the 20 larvae/mL group reached maximum values of 0.089 mg/L and 0.008 mg/L, respectively. Dissolved oxygen (DO) concentrations decreased significantly with increasing stocking density (P < 0.05), and DO concentrations in the 14- and 20-larvae/mL groups were lower than those in the other treatments. Larval growth decreased significantly with increasing stocking density (P < 0.05). A density of 5-8 larvae/mL appeared to be optimal for normal S. subcrenata growth. Larval survival rate decreased with increased stocking density, and survival rate was 35% in the 20 larvae/mL group(P < 0.05). Larvae reared at 8 larvae/mL exhibited comparatively higher settlement density than that of the other stocking density groups(P < 0.05). Comparatively higher settlement density was observed on the lower substrate layer than that on the upper and middle layers (P < 0.05). Settlement time was prolonged and the size of the settled larvae decreased as stocking density increased (P < 0.05). Therefore, a stocking density of 5-8 larvae/mL is recommended for large-scale seed production.