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    Fungal pathogen associated with Rhizophora stylosa: A comparative study between oiled and unoiled sites within Taklong Island National Marine Reserve (TINMAR), Nueva Valencia, Guimaras
    Balanga-an, Kristoffer (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2009-03)
    Mangroves, refer to an assemblage of trees and shrubs that inhabit the coastal intertidal zone in tropical and subtropical regions. They help in the soil formation, protection, and stabilization of our coastal environment as well as serve as shelter and breeding grounds for some of our marine organisms. A mangrove habitat represents the borderline between land and sea and is considered as one of the principal places where spilled oil and associated impacts converge. Oil spill threaten mangroves by predisposing the plants to fungal attacks thereby reducing their resistance to stress and diseases. Studies also show that certain fungi species are able to utilize oil in contaminated mangrove species. This study generally aims to compare the fungal population found on the diseased leaves of Rhizophora stylosa between oiled and unoiled sites in the Taklong Island National Marine Reserve (TINMAR). It also aims to isolate, characterize and identify fungi present in diseased leaves of Rhizophora stylosa using potato dextrose agar (PDA) culture media and determine their frequency of occurrence. Leaf samples were collected from two sites in TINMAR, one of which was contaminated by oil and the other one was not. Three trees were selected to represent each of the two sampling sites (oiled and unoiled), and to each of the selected trees, three diseased leaves were collected. The results of this study showed the dominance of some species of fungi namely, Aspergillus (40%), Penicillium (20%), Cladosporium (13.33%), Monilia (6.67%), Mycelia (6.67%), Humicola (6.67%), and Pestalotiopsis (6.67%). Five out of these seven genera were isolated from the unoiled site while six of these were isolated from the oiled site. Generally, the fungal population was observed to be greater in the oiled site than in the unoiled. This preliminary data indicate that R. stylosa might still be undergoing stress due to the remaining components of the spilled oil in the area. However, this can only be resolved by further monitoring.
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    Comparative growth rates and gross morphology of hybrid catfish Clarias gariepinus (female) x Clarias macrocephalus (male)
    Agase, Mark Christian A. (Division of Biological Sciences, Bachelor of Science in Biology, University of the Philippines Visayas, 2004-03)
    Catfishes are among the groups that has been considered economically important fishes in the Philippines and in other countries. The freshwater catfish Clarias macrocephalus is native to the Philippines but it is becoming scarce in many natural habitats. It is a favorite food dish due to its tender and delicious meet. Aquaculturists these days focus more their attention to the culture of exotic species like Clarias gariepinus and Clarias batrachus that in turn resulted to the near extinction of the native species. There is therefore a need to undertake a breeding program involving this native catfish and other exotic species.A 12-week study was conducted to compare the growth rates of the hybrid catfish C. macrocephalus (♂) X C. gariepinus (♀) in natural ponds and laboratory rearing conditions. In addition, the length-weight relationship was also determined. Gross morphology was also noted in the experiment.Results showed that the trend for SGR of the hybrid in natural pond and laboratory rearing conditions from weeks 2 to 12 is decreasing. Continued feeding of the hybrids on artificial diets results in poor fish growth. T-test revealed that there is a significant difference on the SGR for both the length and weight with hybrids in natural pond rearing conditions being consistently higher than the laboratory set-up.From the linear regression equation, there was no homogeneity of regression, coefficients, or slopes in the mean body lengths (MBL) and mean body weights (MBW) of me hybrids in the natural pond and laboratory rearing condition. It simply means that there is a significant difference on the growth rates of the hybrid as to the type of environment they are reared. The product-moment correlation showed that there is a linear relationship between the length and the weight of the hybrid fish, 7.9305378 X 104 being the constant. Gross morphology of the hybrids includes the appearance of a trident-shaped occipital process, which was not pointed and narrow as in the case of the parent C. gariepinus. A turtle shell-like design arranged bilaterally characterizes the dorsal side of the head. A modification of the dorsal fin was also noted as to the presence of the adipose fin at the posterior end of the dorsal fin, which was about 3-5 mm in length.