Undergraduate Theses
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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 Effect of salinity on survival and growth of Scylla olivacea crabletsAndres, Eileen Beth N. (Division of Biological Sciences, College of Arts ad Sciences, University of the Philippines Visayas, 2002-04)The effect of salinity on survival and growth of Scylla olivacea crablets was investigated. Salinities of 12, 16, 20, 24 and 32 ppt were used as treatments. Survival, molt interval and growth in terms of weight, carapace length and carapace width were measured for two molts. Growth was measured three days after every molt. There was no significant difference on survival of the crablets between salinities at molt 1. At molt 2, survival was significantly higher at 32 ppt compared to survival at 12 ppt but not significantly different from survival at 24, 20 and 16 ppt. Moreover, duration of survival was significantly higher at 32 ppt than at 16 and 12 ppt but not significantly different from durations of survival at 24 and 20 ppt. On the other hand, molt interval was not significantly different at salinities of 12, 16, 20, 24 and 32 ppt from C1 to C2 and from C2 to C3. Although the highest weight, carapace length and carapace width were observed at 20 ppt at molt 1, there was no significant difference in growth of the crablets at different salinities. At molt 2, the highest weight was at 32 ppt, the highest carapace length was at 24 ppt and the highest carapace width was at 16 ppt and 32 ppt. No significant difference was found in growth of the crablets between salinities at molt 2.