UPV Digital RepositoryUPV-DRUniversity of the Philippines Visayas
 

Masters Theses

Permanent URI for this collectionhttps://hdl.handle.net/20.500.14583/12

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1997 - 199912000 - 20032

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Committee Member: search.filters.committeemember.Armada, Nygiel B.

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    Environmental impacts of marine cage farm (Lobster culture) in Van Phong Bay, Khanh Hoa, Vietnam
    Du, Hoang Trung O. (University of the Philippines Visayas, 2003-07)
    The study carried out two surveys at five sites in lobster cage farming activities, during rainy season (November 2002) and dry season (February 2003). It includes 236measured data on physical and chemical parameters of water quality, 115 data on sediment characteristics, and 30 macrobenthic samples. The results of the study indicate that the lobster cage farming activities are related to the accumulation of organic materials on seabed of the cage farm. The impacts of lobster cage farms on water quality might come directly from the cage farm and indirectly from the release of organic and inorganic matter from sediment bottom which significantly changed depending on the season. This could be seen in the total inorganic nitrogen (TIN) concentration at the bottom, which is higher by 6-10 times during the dry season than that during the rainy season. Moreover, cage farming enriches the water column through the release of nutrient and particulate organic matter and affects the sea bottom with deposition of sediment particles. The study clearly marked variation in organic matter and chlorophyll-a concentrations in sediment. In addition, the particulate organic carbon in water samples also showed the negative impact under the cage. The results of sediment trap exhibited high organic content at stations near the cage (stations 2 and 3) as compared to the station farther the cage and the control site. On the other hand, organic matter in surface sediment was significantly higher under the cage than in the control site. This suggests that accumulation of organic material under and near the cage is highly deposited by particles that come from the cage farm. There were observed changes in benthic community in terms of species, abundance, and biomass. Changes in benthic composition were different between stations near the cage and the control site. This indicates that benthic community patterns were affected under the cage and those near the cage farming activities. Macrobenthic communities were dominated by polychaete species during the two surveys. Polychaetes represented more than 55% of benthic abundance as well as greater than 60% ofthe number of species. This study shows that it may be possible that some polychaete species such as Magelona sp, Myriochelle sp, can be important bio-indicators of heavy organic load in the cage farms. On the other hand, polychaete species Prionospio aficana, Orbinia vietnamensis might be considered as candidate indicator species for detection of organic enrichment in the cage farms. In addition, these can serve as baseline information for future studies to evaluate the environmental impact of cage farm. The relationship and interaction between factors that cause eutrophication is therefore particularly important for future studies.
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    Tolerance and behavioral response of Juvenile Siganus guttatus to Abaca Pulp Mill effluent
    Bradecina, Raul G. (College of Fisheries and Ocean Sciences, University of the Philippines in the Visayas, 2003-04)
    Acute bioassay and avoidance-preference tests were done on juvenile S. guttatus using lethal and sublethal concentrations of Abaca pulp mill effluent to assess the fish tolerance and behavioral response to the toxic stress and determine its effect to the chemoreception of biologically important odors. Acute bioassay response data were analyzed by log-probit method. Behavioral response data were calculated from the mean reaction values of the fish samples in the Y-maze apparatus. Results show the fish has a very narrow resistance to the toxic stress of the effluent with LT50 values of 1.6 h for the highest (100% vv-1) and 37 h for the lowest (10%vv-1) concentrations. The 48 h LC50 was located at 9%vv-1 which indicated the fugacity of the effluent and the sensitivity of the fish to its toxicity. The lowest concentration of the effluent with observed significant effect (LOEC) was located at 10%. The fish showed pronounced and significant discriminating ability at lethal concentration of the effluent. Avoidance reactions of the fish were only observed at 9% vv-1 (lethal) and 0.9 % vv-1 (sublethal) concentrations. The avoidance threshold was found at 0.74 % vv-1. Juvenile S. guttatus has a very narrow acuity to the effluent, which was located at a tenth ofthe mean lethal concentration value. Abaca pulp mill did not mask chemoreception of biologically important odors in juvenile S. guttatus.
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    Comparison of the catching efficiency of the traditional and modified fish corral in Panguil Bay
    Acuña, Rodrigo E. (College of Fisheries and Ocean Sciences, University of the Philippines Visayas, 1997-12)
    This study was conducted in two fishing sites of fish corral in Panguil Bay namely; Malaubang, Ozamiz City and Maquilao, Tangub City from November 21,1994 to July 10,1995. Two types of fish corral such as traditional and modified were identified. Results showed that average catch per trip was higher in the traditional fish corral (5.1 kg/day) compared to the modified fish corral (4.2 kg/day). The traditional fish corral also have a higher species richness (mean=105 species) against the modified (mean=50 species). About 90% of the catch of the traditional fish corral are commer­cially important species is significantly higher than the other type (50%). Catches of the traditional and modified fish corral largely consist of shrimps (Metapenaeus ensis: MFC; Penaeus indicus: TFC). Based on the relative density and weight of the total catch, Metapenaeus ensis (mean=222 individuals) is recorded as the most dominant species caught by the modified fish corral while Penaeus indicus (mean=38 individuals) exhibited as a dominant species in the traditional fish corral. Results of the statistical analyses on the data collected on irregular sampling dates show no significant difference on the catches between the traditional and modified. Significant difference is observed on the catches collected during the same sampling dates. Traditional fish corral is more efficient because it has higher catch per trip, species richness and high percentage of commercially important species. Modified fish cor­ral as well, is effective with regards to its catch quantity, however it is inefficient in terms of its catch quality, i.e., of low commercial value.