UPV Theses and Dissertations
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Item Environmental impacts of marine cage farm (Lobster culture) in Van Phong Bay, Khanh Hoa, VietnamDu, Hoang Trung O. (University of the Philippines Visayas, 2003-07)ABSTRACT 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 236 measured 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 ofsediment 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 ofspecies. 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 environmental impact of cage farm. The relationship and interaction between factors that cause eutrophication is therefore particularly important for future studies.Item Tolerance and behavioral response of Juvenile Siganus guttatus to Abaca Pulp Mill effluentBradecina, Raul G. (College of Fisheries and Ocean Sciences, University of the Philippines in the Visayas, 2003-04)ABSTRACT 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.Item Successional development of microfouling and macrofouling on fish farm enclosureReyes, Rikka (College of Fisheries and Ocean Sciences, University of the Philippines Visayas, 2018-06)This study investigated the influence of net color (yellow and green), immersion period, and environmental conditions on micro- and macro-fouling development in marine fish farm. Yellow and green net panels in PVC frame were set-up at lm depth and immersed for 60 days within fish farm vicinities of Igang Marine Station- SEAFDEC, Guimaras Philippines. B. infantis (15-26 %), M. salsuginis (34-50 %) and P. lipolytica (21-21 %) belonging to Gammaproteobacteria and Firmicutes group were the most abundant microfouling bacteria. On the other hand, species such as Bryozoan Bugula sp. (31-38%), tanaids Tanaidae (64-146 ind.100 cm'2), and nematodes Linhomoeidae and Oncholaimidae (142-189 ind. 100cm'2) were the most abundant macrofoulants. MDS ordination revealed that micro- and macro-foulants formed at 7-day were significantly different between green and yellow nets (ANOSIM, p<0.05). Macrofouling gastropods, fish eggs, and macroalgae were present on green at 7-day but only appeared in yellow nets at 15- day. This suggests that lighter color nets in fish farm may delay the development of biofouling. The effect of color, however diminished from 15-day due to the presence of brown film covering all nets. Total biomass, cover, and densities of biofoulant groups (invertebrates, macroalgae, and fish eggs) were not significantly influenced by color (ANOVA, p>0.05) as previously reported. The identity of the foulants and succession pattern suggest the influence of trophic interaction such as predation and competition.