UPV Digital RepositoryUPV-DRUniversity of the Philippines Visayas
 

UPV Theses and Dissertations

Permanent URI for this communityhttps://hdl.handle.net/20.500.14583/10

Browse

Filters

19832

Settings

Adviser: search.filters.advisor.Villegas, Cesar T.

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    A comparative study of the effects of supplementary feeding and artificial substrate on the production of milkfish fingerlings in brackishwater ponds
    Adeyemi, Frederick F. (University of the Philippines Visayas, 1983-03)
    ABSTRACT The growth and survival of milkfish fry in response to supplementary feeding and artificial substrate were evaluated at stocking densities of 75 and 100 fry/m2 for a period of 56 days from August 21 to October 15, 1982. The study was conducted in eighteen 40m2 experimental nursery ponds of the University of the Philippines Brackishwater Aquaculture Centre, Leganes, Iloilo. A 3 x 2 factorial experiment in completely randomized design was used and six treatment combinations between level of inputs (no inputs, supplementary feeding or artificial substrate) and stocking density (75 or 100 fry/m2) were investigated with three replicates per treatment. The best fish growth was obtained in Treatment VI (100 fry/m2 with substrate) with mean final weight and length of 1.59 gm. and 5.36 cm. respectively while Treatment IV (100 fry/m2 without feeding or substrate) gave the poorest fish growth with mean final weight and length of 0.83 gm. and 4.60 cm. respectively. Differences in mean weight and length among treatments were however, not statistically significant. Mean percentage survival was significantly higher at a stocking density of 75 fry/m2 (82.8%) than at 100 fry/m2 (64.1%) but supplementary feeding or artificial substrate ix did not show any statistically significant effect on survival. At either 75 or 100 fry/m2 stocking density, supplementary feeding gave a numerically higher percentage survival than artificial substrate. Economic analysis revealed that a stocking density of 75 fry/m2 without supplementary feeding or artificial substrate was the most profitable treatment with a return on investment of 39.2%. At a stocking density of 100 fry/ m2, supplementary feeding with rice bran was more profitable than the use of artificial substrate with returns on investment of 22.6% and 9.1% respectively
  • Thumbnail Image
    Item
    The effects of different salinity and organic matter levels on the growth of blue-green algae
    Bantillo, Rosario R. (College of Fisheries and Ocean Sciences, University of the Philippines Visayas, 1983-03)
    A one-month culture of lab-lab to determine the growth of blue-green algae in three levels of salinity ( 15 ppt = S1, 30 ppt = S2 and 45 ppt S3) and two levels of organic matter (3.4 to 4.4% = OM1 and 6.5 to 7.8% = OM2) was conducted using a twenty-two plastic containers (diameter = 43 cm; height - 49 cm) at the University of the Philippines in the Visayas Brackishwater Aquaculture Center, Leganes, Iloilo. The study utilized a 3 x 2 factorial experiment in completely randomized design with three replicates. Organic matter levels of the soil affected the chemical properties of soil and water (available phosphorus, reactive phosphorus, ammonia-nitrogen and pH). The higher the organic matter level, the higher the pH and the concentrations of ammonia and phosphorus. On the other hand, salinity did not apparently affect the fluctuations in ammonia, phosphorus and pH due to water replenishment to maintain treatment levels of salinity. Earlier rapid growth of blue-green algae commencing on the 3rd to the 15th day was observed at higher organic matter level. While at lower organic matter level, this occurred only on the 18th to the 28th day. Blue-green algae population (units/ml) was observed highest in treatment IV (S1 OM2; 1,262,113) followed by treatments III (S3OM1 ;761,338); II (S2OM1; 514,788); I (S1OM1 ;494,375); V (S2OM2; 413,750); and, the lowest was obtained from treatment VI (S3OM2; 394,275). The relative percentage proportion of blue-green algae in the lab-lab complex showed that it composed 17.7% in treatment IV, 16.86 % in treatment III, 16.64% in treatment II, 15.82% in treatment I, 15.2% in treatment V and 14.9% in treatment VI. These, however, did not significantly vary among treatments. A low correlation coefficient (r) between the population count and the selected parameters: reactive phosphorus, water pH, soil pH and available phosphorus was obtained while a negative correlation was obtained between the population and ammonia-nitrogen. Significantly higher biomass (ash-free dry weight) of lab-lab was obtained in higher organic matter (OM2) and at 45 ppt salinity (S3). The highest biomass (ash-free dry weight) was obtained in treatment VI (S3OM2; 0.160 g/cm2) while the lowest was obtained in treatment I (S1OM1 0.012 g/cm2). The algal count of lab-lab also showed a significant difference in the organic matter levels but no significant difference on the salinity levels. The highest algal count was obtained in treatment V (S2OM2; 6,773,542 units/ml) and the lowest count was obtained in treatment II (S2OM1; 2,328,792 units/ml). However, the primary productivity based on O2 production showed a significantly higher production in the lower organic matter and at higher salinity level (30 ppt.). The highest O2 concentration was obtained in treatment III (S3OM1 ;5.759 ppm) and the lowest was obtained in treatment V (S2OM2; 4.19 ppm).