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UPV Theses and Dissertations

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Committee Chair: search.filters.chair.Corda, Diana EdnaDepartment: search.filters.department.College of Arts and Sciences

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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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    Biosorption of Copper (CU) and Lead (PB) by heavy metal-resistant bacterial isolates from Iloilo River
    Ampuan, Naira Mitz W. (Division of Biological Sciences, College of Arts and Sciences,University of the Philippines Visayas, 2012-04)
    Many indigenous organisms isolated from sites contaminated with heavy metals have tolerance to heavy metal toxicity and these microbial activities have always been the natural starting point for all biotechnological applications. It is therefore necessary to isolate bacterial strains with novel metabolic capabilities. In this study, a total number of 18 heavy metal-resistant bacteria (10 Pb-resistant and 8 Cu-resistant) were isolated from Iloilo River sediment samples (10° 41.974’N, 122°34.187’ E). Biosorption of Cu and Pb by the bacterial isolates was characterized to evaluate their applicability for heavy metal removal from industrial waters. Selecting the highest resistance to metal toxicity’ and biosorption, 4 isolates were identified by phenotypic characterization. Identification of the top four metal-resistant isolates designates: Vibrio charchariae (83%) for Cu4; Vibrio harveyi (79%) for Cu6; Moraxella equi (100%) for Pb8; and Phoecoenobacter uteri (92%) for Pb9. Evaluation of specific metal biosorption by the isolates after incubation for 48 h suggested that none of the isolates have good potential for bioremoval of metals from contaminated environments.