A Study in the Growth of Hard Clam (Meretrix lusoria) Cultured in Different Models

Three experiments were conducted in this study. A bulk of seawater was used to drain in the Experiment I in order to keep nutrient salts of sea water in a lower level. Partial recirculation system was introduced in Experiment II. Gracilaria tenuistipitata, remover of nutrients, and artificial feed, substitution of microalgae, were included in the Experiment III. In Experiment I, stock seawater with 0.02 ppm phosphate was used to maintain a low concentration of phosphate (0.1 ppm) in the water of the tank. During the experiment, the shell length of hard clam (Meretrix lusoria) significantly increases from 27.5 ± 0.9 mm to 28.8 ± 1.15 mm. The body weight of hard clam significantly increases from 5.81 ± 0.18 g to 6.79 ± 0.29 g. Percentages of an increment in the shell length and body weight of hard clam in the end of experiment were 4.75% and 17%, respectively. The concentration of phosphate in the seawater of clam aquarium in Experiment II was kept no more than 0.1 ppm. The body weight of hard clam at stocking density of 64, 96, 128 clams/aquarium all significantly increases from 1.71 ± 0.19 g to 2.21 ± 0.23 g, from 1.69 ± 0.15 g to 2.13 ± 0.29 g, from 1.87 ± 0.11 g to 2.23 ± 0.17 g, respectively. Percentages of an increment in the body weight of hard clam at stocking density of 64, 96, 128 clams/aquarium in the end of experiment were 28.7%, 26.1% and 19.4%, respectively. Experiment III was designed to remove nutrient salts from clam aquarium by culturing Gracilaria. The concentration of phosphate in the water of clam aquarium was kept at 0.1~0.16 ppm during the experiment. The shell length and body weight of hard clam at stocking density of 64, 96, 128 clams/aquarium all have no significant change during the experiment. Therefore, the accumulation of phosphate inhibiting the growth of hard clams was concluded.

關鍵字

Hard clam ； Growth ； Microalgae ； Seaweed ； Phosphate

並列摘要

本研究進行三個實驗，第一個實驗以大量乾淨海水更換實驗桶的海水，維持水中低營養鹽的濃度；第二個實驗進行半循環式的養殖；第三個實驗引進去除營養鹽的海藻(龍鬚菜)和人工飼料(取代微藻)。在第一個實驗中，以大量海水(磷酸鹽含量為0.02ppm)更換實驗桶的海水，在實驗過程中維持試驗水磷酸鹽的含量在0.1 ppm以下。實驗過程中發現文蛤的殼長顯著地由27.5 ± 0.9 mm成長至28.8 ± 1.15 mm，而體重則由5.81 ± 0.18 g顯著地增加至6.79 ± 0.29 g，文蛤殼長和體重的增加百分比分別為4.75%和17%。在第二個實驗的過程中，試驗水磷酸鹽的含量亦維持在0.1 ppm以下，在飼養密度為64、96和128 clams/aquarium的文蛤體重分別顯著地由1.71 ± 0.19 g、1.69± 0.15 g和1.87 ± 0.11 g增加至2.21 ± 0.23 g、2.13 ± 0.29 g和2.23 ± 0.17 g。而文蛤體重增加百分比則分別為28.7%、26.1%和19.4%。在第三個實驗，則以龍鬚菜去除營養鹽，然而在實驗過程中，試驗水磷酸鹽的含量仍維持在0.1~0.16 ppm，在三個飼養密度文蛤的殼長和體重沒有顯著的增加，顯示磷酸鹽會抑制文蛤的成長。

並列關鍵字

文蛤；成長；微藻；海藻；磷酸

國際替代計量

A Study in the Growth of Hard Clam (Meretrix lusoria) Cultured in Different Models

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