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    Abundance, composition and distribution of phytoplankton in Mindoro Strait
    Bayona, Riena Rose M. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2008-04)
    Phytoplankton in Mindoro Strait, north of Palawan, were investigated from the samples taken last April-May 2007. Twenty stations were selected from over 40 stations surveyed. Samples were collected by filtering 50L of surface waters through 20 micrometer mesh plankton net using a 10L bucket. Phytoplankton assemblage was grouped into four major taxa. Diatoms dominated the area. It recorded the highest mean density of 314.9indivL-1. It was followed by blue green algae that noted a mean density of 165.69indivL-1. The next most abundant was dinoflagellates that recorded a mean density of 51.59indivL-1 and then the group of silicoflagellates. It recoded 35.69indivL-1 mean density. The top three species were Trichodesmium, Thalasiothrix and Isthmia. Protoperidinium represented the dinoflagellates among the top genera while Eutintinnus recorded the highest silicoflagellate. Higher concentrations were found in the midst of the oceanic region where water currents mainly pass. Overall abundance is lower than other nearby waters. This is maybe due to the effect of water currents.
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    Abundance, composition and distribution of phytoplankton in West Central Sulu Sea
    Bria, Jed B. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2008-11)
    A total of 28 stations were sampled for abundance, composition and distribution of phytoplankton in the West Central Sulu Sea. The samples were taken from 15-30 April 2007. Samples were collected by filtering 50L of surface water through a 20 pm mesh plankton net. A total of 96 phytoplankton genera were identified and were grouped into four major taxa. The overall mean density was 444.6 cells/L. Diatoms were the most abundant, with the mean density of 213.5 cells/L. The most abundant diatom genus was Chaetoceros. Blue-green algae showed the second-highest mean density of 127.6 cells/L. Trichodesmium was the most abundant genus among the two blue-green algae identified. Trichodesmium was also the most abundant genus, comprising 28.1% of all phytoplankton identified. Dinoflagellates and silicoflagellates were ranked third and fourth among the four major taxa with 77.5 cells/L and 28 cells/L, respectively. Protoperidinium was the most abundant dinoflagellate, while Amphorella was the most abundant silicoflagellate. They made up 6.2% and 1.2 % of all phytoplankton identified, respectively. The stations located along the coast of Palawan and near the Tubattaha Reef Marine National Park showed the highest phytoplankton concentrations.
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    Diel feeding patterns of angelwing clam Pholas (Monothyra) orientales (Gmelin, 1970)
    Alojepan, Marbe Joy L. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 1999-04)
    Filtration rate of Pholas orientalis measured using the indirect suspension deletion method and monitored by direct algal cell counts. Phytoplankton Isochrysis galbana was used as food at an algal cell concentration of 2.5 x 103 cells ml ”'. Biological rhythms have been demonstrated in all animals and plants except bacteria. They control rhythmic patterns in behavior and physiology of a living organism. Biological rhythms, or oscillations, have a “period” that is measured from one arbitrary point or phase of the rhythm to the next occurrence of that phase. They are best demonstrated in a 24 h cycle or circadian cycle. There is a widely varying feeding activity in the 24h cycle of P. orientalis observed at a constant temperature of 27$C and hydrogen ion concentration of 35%o Like any other bivalves, P. orientalis has defined feeding periods equivalent to food uptake at 2400h-0300h. Such observation could be supported by a previous study by Corda stating that optimal feeding was obtained at total darkness. Periods of digestion occur shortly after the periods of feeding. P. orientalis when actively feeding were observed to have extended siphons, larger valve openings, and an inclination of 45. One primary external stimulus that affected filtration rate was the amount of light present. Biorhythms provide temporal information, such as the time of day or season of the year, which facilitates adaptation of the organism to internal or external environments.