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UPV Theses and Dissertations

Permanent URI for this communityhttps://hdl.handle.net/20.500.14583/10

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1998 - 20004

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Committee Chair: search.filters.chair.Gacutan, Ma. Vicenta C.

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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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    Community structure of a ten-year-old naturally, regenerating mangrove stand in Baguingin, Tigbauan, Iloilo
    Animas, Ruphil May J. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 1999-04)
    The structure of the mangrove community in Baguingin, Tigbauan was studied using the transect line plot method with seven plots established. Community structure is described in terms of the following parameters: basal area, stems per hectare, relative density, relative frequency, relative dominance, and importance value of the species and the Shannon Index of Diversity. Variations in these parameters are correlated with certain physico-chemical factors-- air and water temperature, soil pH, water salinity, land elevation- and the degree of human influence. Three true mangrove species were found in the area: Excoecaria agallocha, Avicennia marina, and Avicennia alba. A. marina was found to have the highest relative density of 70.8%. relative dominance of 52.35% and importance value of 169.82. A. marina and A. alba have equal relative frequency of 46.67%. Seedlings and saplings of A. marinadominate the area, indicating that the community is a young and regenerating stand. Basal area significantly increased from sea to land ( 53.68 cm2 to 431.66 cm2) and from creek to land ( 8.83 cm2 to 366.54 cm2). Shannon Index of Diversity gave a result of 0. The very low diversity index means that there is uneven distribution of individual trees among the species, and only a few kinds of species were present and are centered around only two genera, Avicennia species and Excoecaria agallocha.
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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.
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    A survey of the catch composition of fyke nets in the Iloilo river
    Andrada, Kristina Abelaine D. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2000-04)
    A survey of the catch composition of fyke nets in the Iloilo River Estuary during the months of August 1999 and February 2000 show that catches are dominated by Metapenaens crisis and ilossygobius sp. The 18 species caught are : 9 fish species, 5 shrimp species, and 4 crab species. The index of similarity 0.3 between the monthly samples is low which means that there is minimal degree of similarity between the species composition of the catches. There is no significant difference between the total catch volumes per day for the months of August 1999 and February 2000 which means that the seasons do not affect the volume of the catch.