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UPV Theses and Dissertations

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    Salinity tolerance of the angelwing clam, Pholas orientalis larvae
    Aguaras, Lovie Grace P. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2011-03)
    Pholas orientalis, locally known as “diwal” is one of the commercially important bivalves in the Philippines due to its delicate and sweet taste. An experiment was conducted to determine the salinity tolerance of the 24-hour-old larvae of this clam when reared in different salinity levels of 25, 30, 35, and 40 ppt. The experiment lasted for 15 days at a rearing temperature of 25° C - 27° C. Determination of survival rates and water change were done twice every week. The data gathered were then analyzed using one-way ANOVA. Results showed that survival rates were significantly high at salinities of 30-35 ppt and were significantly low at salinity levels of 25 and 40 ppt. It was also observed that there was an increasing trend of mortality with prolonged exposure to different salinity levels. This could be attributed to the limited osmoregulatory capabilities of the larvae. When reared at low salinity levels, larvae were faced with the danger of too much water entry which eventually led to death. Meanwhile, when reared at high salinity levels, the larvae died due to outward movement of water which resulted to dehydration. Information on the salinity levels that could be tolerated by diwal larvae will be an important factor in the development of larval rearing techniques for successful hatchery operations. The juveniles or seeds produced in the hatchery could be used to restock the depleted resources in the wild.
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    Evaluation of feeding performance of early siganid, Siganus guttatus, larvae fed with mixed zooplankton
    Andrade, Maria Shiela S. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 1999-04)
    Siganus guttatus is an economically important rabbitfish for commercial farming. It is very important to evaluate their feeding performance particularly the effects of different diets for this larvae and to determine their growth and survival after being fed on different diets. Newly-hatched siganid, Siganus guttatus, larvae were reared in 500-L fiberglass tanks and fed either on copepod nauplii and rotifers alone or combination of both. Copepod nauplii proliferated in tanks consisted mainly of Pseudodiaptomus sp., and Acartia sp. Siganid larvae successfully commenced feeding (feeding incidence) on early stage copepod nauplii even if their abundance was low. Selective feeding ability of larvae seemed to start from day 6 and the larvae thereafter preferred to feed nauplii than rotifers. Survival of the siganid larvae was significantly higher when fed with with combination of rotifers and copepod nauplii compared to those fed with either rotifers or copepod alone. The growth of the larvae however are the same for all treatments. Results of this study suggest that coastal calanoid copepods of the genus Pseudodiaptomus sp. and Acartia sp. could be reproduced in tanks and their nauplii can be used as food for siganid larval rearing.