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UPV Theses and Dissertations

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Committee Chair: search.filters.chair.Gacutan, Ma. Vicenta C.SDG: search.filters.sdg.SDG 15 - Life on land

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    Effect of sperm concentration on fertilization and the timing of early developmental stages of Imbaw, Anodontia edentula
    Arboleda, Erika A. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 1999-04)
    In this study, effect of sperm concentration to fertilization rate is investigated. Also, the timing of early developmental stages is done. Sperm concentration at seventy' is most effective although not significantly different. In the range used, effect of sperm concentration to fertilization rate is broad. The concentration of ten sperm per egg is least effective and significantly different from all the rest. In developmental stages, polar body extrusion is observed after ten minutes from fertilization. Two-cell and four-cell is formed within an hour. After two hours, eight-cell and sixteen-cell stage is noted. The larval stage trocophore is already present after the fifteenth hour. The straight-hinge veliger can be observed after twenty-four hours.
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    Growth of the telescope snail, Telescopium telescopium (Linne) in brackishwater ponds
    Apistar, Jobert H. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines, 1998-04)
    Samples of T. telescopium were collected every month, from April to October 1997 for 6 months, in brackishwater ponds. Allometric relationships were defined by comparing shell length with shell width, as well as various body weight proportions including total weight with shell, total volume with shell, visceral weight and visceral volume. A total of 5 cohorts with growth rates ranging from 0.45 - 0.67 mm-day- were observed using the Bhattacharya analysis. A high mean growth rate of 0.56 mm-day- (sd = 0.07, n= 5) was estimated by joining the modes of the cohorts between successive sampling months. Low inverse correlations were observed between mean shell length and various environmental parameters (i.e. salinity, air temperature, water temperature and organic matter content) possibly explained by the species' environmental adaptations. On the other hand significant correlation was observed between mean shell length and density, indicating the possible role of overcrowding in these habitats.