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    Effect of Physico-chemical parameters of rearing waters on survival rates of larvae and post larvae of Penaeus monodon in two hatchery systems
    Alindong, 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.
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    Salinity tolerance of the angelwing clam, Pholas orientalis larvae
    Aguaras, Lovie Grace P. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2011-03)
    Pholas orientalis, locally known as “diwal” is one of the commercially important bivalves in the Philippines due to its delicate and sweet taste. An experiment was conducted to determine the salinity tolerance of the 24-hour-old larvae of this clam when reared in different salinity levels of 25, 30, 35, and 40 ppt. The experiment lasted for 15 days at a rearing temperature of 25° C - 27° C. Determination of survival rates and water change were done twice every week. The data gathered were then analyzed using one-way ANOVA. Results showed that survival rates were significantly high at salinities of 30-35 ppt and were significantly low at salinity levels of 25 and 40 ppt. It was also observed that there was an increasing trend of mortality with prolonged exposure to different salinity levels. This could be attributed to the limited osmoregulatory capabilities of the larvae. When reared at low salinity levels, larvae were faced with the danger of too much water entry which eventually led to death. Meanwhile, when reared at high salinity levels, the larvae died due to outward movement of water which resulted to dehydration. Information on the salinity levels that could be tolerated by diwal larvae will be an important factor in the development of larval rearing techniques for successful hatchery operations. The juveniles or seeds produced in the hatchery could be used to restock the depleted resources in the wild.
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    Comparison of the growth of green algae, Nephroselmis sp. at different media
    Agana, Julie Ann E. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2004-03)
    Green algae play a significant role in the maintenance of the hatchery of economically important crustaceans, where a continuous supply of algae is needed to feed the larvae. Moreover, microalgae have the potential to be used to produce chemically complex molecules, which are difficult to synthesize. Thus, the present study was conducted to compare the growth of the green algae, Nephroselmis sp., using three different media. Specifically, the study aims (1) to compare the effect of different media on the growth of Nephroselmis sp. and (2) to determine which medium is the most suitable for growth of Nephroselmis sp. The result of the study showed that there was no significant difference in the growth of the green algae Nephroselmis sp. at three different media. The results showed that quantities of chemical composition of the different media are already sufficient for the growth of Nephroselmis sp.
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    Growth development, survival and settlement rate of sandfish (Holothuria scabra) larvae reared using different microalgae and settlement and settlement cues
    Sibongga, Rema C. (University of the Philippines Visayas, 2017-07)
    ABSTRACT Growth, development and survival of Holothuria scabra larvae fed with different microalgae were studied. In the first experiment, Chaetoceros calcitrans, Rhodomonas sp. and Tetraselmis tetrathele at 10000, 20000, 30000 and 40000 cells ml-1 were compared. Larvae fed with Rhodomonas sp. at 10000 cells ml'1 had the highest mean body length (BL) at late auricularia (1032.41±38.70 μm). However, those fed with C. calcitrans at 20000 cells ml'1 showed higher daily growth rate (DGR) of 31.4±5.2 pm d-1. Development to 50% competent larvae was shorter using C. calcitrans at 20000 and 30000 cells ml'1. At 12 days post-fertilization (DPF), larvae fed with C. calcitrans at 20000 and 40000 cells ml'1 showed significantly higher % doliolaria (p<0.05) and those fed at 20000 cells ml-1 showed highest survival of 53% at 14 DPF. In the second experiment, three combinations of microalgae containing 10000 cells ml'1 of each microalga were used: C. calcitrans and Rhodomonas sp., C. calcitrans and T. tetrathele, and Rhodomonas sp. and T. tetrathele. Larvae fed with mixed C. calcitrans and Rhodomonas sp. showed significantly higher mean BL at late auricularia (991.0±15.8 pm) and DGR (43.8±9.9 μm d-1) (p<0.05). Larvae showed faster development and higher survival of 86% at 10 DPF. In summary, C. calcitrans at 20000 cells ml'1 is recommended as a single diet while a combination of C. calcitrans and Rhodomonas sp. as a mixed diet. Settlement of H. scabra on substrates with different cues was also investigated using corrugated plastic sheets (CPS) as substrate and Navicula, C. calcitrans paste and Spirulina paste as cues. CPS without cue served as control. Although no significant differences, Spirulina paste showed highest settlement rate (88.54%) followed by Navicula and C. calcitrans paste. Control showed significantly lowest settlement rate. Therefore, Spirulina paste best induced settlement of H. scabra. However, Navicula and C. calcitrans paste may be used as cheaper settlement cue substitutes.
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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)
    ABSTRACT 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.
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    Evaluation of commercial shrimp larval diet as replacement of live foods in mudcrab larval rearing
    Burlas, Michael Rey J. (College of Fisheries and Ocean Sciences, University of the Philippines Visayas, 2014-04)
    ABSTRACT The use of live food such as rotifer and Artemia entails high cost of production in the hatchery. Hence, the general objective of the study was to reduce the use of natural food in the larval rearing of mud crab. The first study was conducted to screen four types of commercial shrimp formulated larval diet (Lansy, P. japonicus, P. monodon and BP Nippai) in mudcrab Scylla serrata larval rearing. Formulated diets were fed to each stage from zoea 1 to megalopa at an equivalent of 100% dry weight of the live food. Growth index and survival were determined at the end of the experiment. Results showed that of zoea 1 fed any of the formulated diet did not molt to zoea 2. When formulated diets were fed to zoea 2, 3 and 4, there was a decreasing trend in the growth index and survival as the larvae developed. Zoea 5 fed any of the formulated diet failed to molt to megalopa stage. Among the four formulated diets, BP fed larvae had better growth and survival. BP was then used in the second study to determine the amount of formulated diet (FD) that could replace natural food (NF) such as rotifer and Artemia. Results showed that larvae fed 25% FD + 75% NF and 50% FD + 50% NF had better survival and growth than those larvae fed 100% FD + 0% NF, 75% FD + 25% NF and 0% FD + 100% NF. This study indicates that shrimp larval diet in combination with formulated diet can be used to improve the growth and survival of S. serrata larvae.