Masters Theses

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Spatial distribution of eggs, larvae, and juveniles of Eyebrow goby (Oxyurichthys ophthalmonema) in Batan Bay Estuary, Aklan
David, Alemar V. (University of the Philippines Visayas, 2019-06)
To understand better the biology of eyebrow goby Oxyurichthys ophthalmonema, the spatial distributions of its eggs, larvae and juveniles were investigated in Batan Bay Estuary, Aklan from October 2016 to September 2017 by employing a fisheries- independent methodology. Nesting grounds were located through burrow assessment followed by physico-chemical characterization of identified nesting grounds. Fifteen stations were established all over the study area. Results showed that O. ophthalmonema burrows were present in mudflats all over the study area. Of the 196 burrows assessed in detail, only 34 (17%) burrows had the presence of nesting adult O. ophthalmonema. For the spatial distribution of eggs, they were only found in Moto, Jalas and Kapispisan burrows. The highest observed density was obtained in Kapispisan at 5 eggs/burrow. For the spatial distribution of larvae, they were only found in 9 stations with the Jalas showing the highest density at 32 larvae per 100m3. For the spatial distribution of juveniles, they occurred in all stations but the density was higher in Kapispisan at 4 juveniles per 1000m2. The nesting grounds are located near the upper river tributaries with substantial mudflats and mangrove forest cover. The physico-chemical characteristics of the nesting grounds were as follows: 24.50-26.67ppt for salinity, 29.75-31.25°C for water temperature, 3.26-3.55 for sediment pH (dry weight sediment, DW), 29.82-77.89μg/g for iron (DW sed), 2053-5378μg/g for Sulphur (DW sed), 1.50-8.24μg/g for phosphorus (DW sed), and 0.52-1.15% organic matter (DW sed). The physico-chemical characteristics of the water and sediments of Batan Bay Estuary is favorable to nesting of O. ophthalmonema. There is a need, therefore, to protect these habitats from threats that may negatively affect the nesting of O. ophthalmonema.
Successional development of microfouling and macrofouling on fish farm enclosure
Reyes, 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.