Undergraduate Theses
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Item A preliminary study on the freezing tolerance of milkfish (Chanos chanos, Forskal) embryosBuendia, Jeremiah C. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 1994-03)Milkfish embryos of blastula and C-shaped stages were tested for cryoprotectant toxicity using DMSO and glycerol at 10%, 12% and 15% concentrations. Survival and hatching as well as the effects of freezing were observed. Glycerol was more toxic than DMSO. Freezing at 4°C resulted in the decrease of hatching, and ice crystal formation killed the embryos during the process of freezing to -80°C. C-shaped embryos had a higher survival and hatching than the blastula stage embryos in the toxicity and cold shock tests.Item The effect of different levels of salinity on the spanning of ablated mudcrab Scylla serrataBueno, Jesse L. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 1994-04)Four salinity treatments with salinity levels of 15 ppt, 25 ppt, 35 ppt and 45 ppt with six replicates per treatment were utilized to determine its effect on the spawning of sexually mature bilaterally ablated mud crab Scylla serrata. The crabs range in weight from 250 grams to 580 grams and carapace width from 12.5 cm. to 16.5 cm. The results of the study showed significant difference (P<0.05) in the number of days when spawning occurred. The shortest duration when spawning occurred was at 25 ppt salinity with a mean value of 9.5 days. This was followed by 35 ppt and 15 ppt salinities with mean values of 15.69 days and 19.83 days respectively. Highest number of days when spawning occurred was at 45 ppt salinity at 24 days. All crabs died 2-3 days after spawning.Item Embryonic development and hatching rate of grouper (Epinephelus suillus) eggs incubated at different stocking densitiesBofill, Aileen B. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 1992-04)Fertilized eggs of the grouper Epinephelus suillus were obtained from natural spawning of broodstock reared in a 50—t concrete tank at the Aquaculture Department of the Southeast Asian Fisheries Development Center, Tigbauan, Iloilo. The development of eggs incubated at three different stocking densities (50, 1OO, and 150 eggs/1) were monitored. Hatching rates in the different treatments were also determined. Fertilized eggs were floating, non—adhesive, transparent, and spherical in shape with a mean diameter range of 0.83 — 0.84 mm. The yolk was colorless, transparent, and possessed a single oil globule of 0.22 mm in diameter. The eggs have developed into the 2—cell stage 45 min after stocking. Eggs incubated at 1OO eggs/1 hatched 24 h after stocking, while hatching occurred after 27 h and 5 min at 50 eggs/1. No hatching was observed at 150 eggs/1 stocking density even after 28 h post—stocking. Water temperature and salinity during the experiment were 27 ° C and IB ppt, respectively.Item Histomorphological study of the gonads of Pholas orientalisBeluso, Michelle O. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 1994-04)A total of five "diwal", Pholas orientalis, two of which wore obtained from Hinigaran, Neg. Occ. on January 1995 and three from Lanas, Barotac Nuevo on February 1994, were examined for the histomorphological study of the gonads of the species. Among the five samples, two were males and three were females. No hermaphrodites were encountered. Macroscopical examination showed that the gonads were diffused in the visceral mass extending from the anterior to the posterior part of the animal. The gonads were arborescent in form and creamy in color. No external sexual differences were observed. Histological examination showed that male and female gonads were scattered in the visceral mass and concentrate most around the stomach. Male and female gonads consist of follicles which were lobular and embedded in the connective tissues. Three sexual maturity stages were observed among the five specimens, which are the late active, ripe, and partially spent stages. During the late active stages in both male arid female gonads, developing gametes (spermatocytes and young oocytes, respectively) are attached to the follicular wall with maturing gametes lying free in the follicular lumen. At the ripe stage, male gonads showed mature sperms free in the follicle lumen with sperm tails radiating into the center of the lumen. In females, ripe oocytes are free in the follicle lumen with some maturing oocytes still attached to the folli- cular wall by a slender stalk. Partially spent stage was observed only in females. Spent gonads showed spaces in ovarian follicles due to loss of ova through spawning (1938). Since there is a growing demand for "diwal", interest on this species had picked up lately. One of the earliest studies on P. orientalis was the study on the "diwal" fishery in Neg. Occ. conducted by Ablan (1938). The larval biology and mariculture of the angelwing clam, Cyrtopleura cos- tata, were studied by Gustafson, et al. (1991) and investigations into spawning and hatchery technique for P. orientalis are underway (Gustafson, et al., 1991). Studies on the biology of P. orientalis are few and in fact no literature regarding reproductive biology of the species was obtained. Thus, this study was carried out with the following objectives: (1) to determine the location of the gonads in the visceral mass of P. orientalis, (2) to describe the histomorphology of the gonads, and (3) to differentiate the gonadal conditions histologicallyItem Determination of the fungal flora in the rearing water, eggs, larvae and post-larvae of Penaeus monodon in a large-scale hatchery systemBaes, Glanee F. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 1995-03)The rearing water and homogenized. eggs, larvae, post-larvae of Penaeus monodon were taken front the large-scale hatchery system. These were counted, isolated and identified. Analysis was done by determining the mean, standard deviation and skewness of the data. The result showed that the skewness of the yeast and mold counts in the rearing water were 0.93 and 0.64, respectively 'while that in the homogenized samples were 0.92 and 1.09, respectively. These showed that the data were positively skewed, hence, fungi were greater in the early larval stages than in the later stages. The mean showed that yeast yielded greater counts as compared to the molds. Furthermore, rearing water have also higher fungal count than that of the homogenized prawns. The fungi identified were Aspergillus, Balanium, Bispora, Cladosporium and Phialomysis. In the study, the fungi identified were the normal mycoflora which did not adversely harm the prawn due to favorable hatchery conditions, there being no disease outbreak during the duration of the study.Item Effect of Physico-chemical parameters of rearing waters on survival rates of larvae and post larvae of Penaeus monodon in two hatchery systemsAlindong, Ray Lauron (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 1995-03)Physico-chemical parameters such as temperature, pH, salinity, and D.O. of the small-scale and large-scale hatchery system were monitored daily for a duration of two months. The relationship between the physico-chemical parameters and the survival of the different larval and post-larval stages between the two hatchery systems was then determined. Results showed that the physico-chemical parameters obtained from the small-scale hatchery system were favorable to the survival of the larval stages of the prawn. However, the physico—chemical parameters obtained from the large-scale hatchery system were more suitable for the growth of the post-larval stages.Item Effects of freezing and thawing on some agar parameters of Eucheuma spinosum and Gracilaria confervoidesAbelende, Ma. Orfa R. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 1995-05)Agar was extracted from two agar-containing red algae species, namely Gracilaria confervoides and Eucheuma spinosum. Qualitative assessment was made on the agar extracts, which included percentage yield, gel strength, syneresis, and hysteresis range. The quality of agar extracts derived from this study was compared to commercial agar-agar. The. effects of each parameters, repeated freezing and thawing on agar were also investigated. Qualitative test showed that percentage yield from Gracilaria was higher than Eucheuma. Gel strength and hysteresis range of agar from commercial sources and Gracilaria were higher compared to Eucheuma. On the other hand, syneresis range was highest in Eucheuma agar. Repeated freezing and thawing lowered percentage yield and syneresis but increased gel strength and hysteresis of agar extracts from agar sources used.Item Species composition and food preference of fishes in two seagrass beds in Taklong Island, GuimarasApostol, Archie E. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 1997-08)Seagrass bed is known as one of the most important biological system that serves as nursery areas, resting and hiding place of small organisms and feeding ground for fishes. Investigations on population structure and composition of fishes have been done to monitor species diversity, abundance, and distribution in seagrass ecosystem. However, few studies have related food preference to community structure. This study aims to determine the species composition and food preference of fishes in Bagatnan and Kalirohan seagrass beds in Taklong Island, Guimaras. Once-a-month sampling in Taklong Island was conducted during the months of October, November, and December 1996. The collection of fishes was done using gill net. It was casted —50 meters from the shore and parallel to the shore during high tide and hauled during the next low tide. All gathered fishes were measured and preserved in 10% formalin. For stomach content analysis, stomachs of fishes were excised, preserved and brought to the laboratory for analysis. Contents were flushed out from the stomach, sorted and identified to major groups (as food items). Based on the results of the study,Siganus fuscecens, Scarus psittacus, and Dichistodus chrysopoecilus were the most abundant species of fish collected in Bagatnan and Kalirohan seagrass beds Kalirohan had a slightly higher species diversity and species richness value than Bagatnan. Most of the fishes caught were omnivores and this feeding mode was clearly reflected in the results of the stomach content analyses Also, the most abundant and common species (e.g. S. fuscecens & Dischistodus spp) had various food items on their stomach. Seagrass blades, algae, foraminiferans and other seagrass-associated organisms (e g. fishes, sipunculids, crustaceans and molluscs) were present in the stomach of many species. Of these, foraminiferans are the most frequently encountered among the food items. A few species fed on single item such as Synodus variegatus, Atherioromorus sp. and Amanses scopes which were found to feed exclusively on fish, algae and seagrass respectively. Although factors like type of fishing gear used and its mesh size and the time of sampling may have biased the kind and size of fish collected, it was clear that the extent of seagrass cover and availability of other food sources (algae and meio- & macrofauna) have influenced the abundance, species diversity & richness and the food consumed (and perhaps, also preferred) by the fish fauna.Item Anti-microbial activity of aqueous extracts from selected Philippine soft coral speciesAguilar, Remotito A. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 1994-03)Five species of soft corals were collected from Taklong Islands Guimaras and then extracted with water. The aqueous extract was assayed for anti- microbial activity. Potent extracts were tested for its minimal inhibitory concentration against the most sensitive microorganisms. The equivalent potency was also determined using PEN VK as the standard antibiotic. Lobophyton was found to inhibit S. aureus at 50% concentration of the aqueous extract (ATCC 25923) while Sinuloria. sp. was found to inhibit the growth of both S. aureus (ATCC 25923) and B. subtilis (NSRI-1). Aqueous extracts of Lobophyton sp.has an equipotency of 6.64 units/ml of PEN VK against S. aureus, whereas aqueous extracts of Sinulcria sp. has a potency of 104 units/ml of PEN VK against B. subtilis.