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    Filtration rate of the marine clam, Kaltelysia sp. at different light intensities and fed with microalgae Isochrysis galbana and Chaetoceros calcitrans
    Bravo, Agnes Therese A. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2005-04)
    Filtration rate of the marine clam, Katelysia with body lengths ranging from 5-6 cm and body weight from 45-65 g were determined by using the indirect method of suspension depletion and monitored by direct algal cell count. The effects of light intensity and algal species on the feeding behavior of the clam were determined. The first treatment involves total darkness where the basins containing the clams were covered with black plastic bag. In the second treatment, the basins with the clams were placed under ordinary light condition (12h light; 12h dark) and in the third treatment, the basins with the clams were positioned under a 20-watt bulb with continuous illumination (24h light). Results showed significant differences in the filtration rates of clams in different light intensities. It showed higher filtration rate in the total darkness treatment (F=0.132555907) followed by the 12h light: 12h dark treatment and lowest at the treatment provided with 24 h illumination. Apparently, illumination affected valve opening and siphon extension of the clam which also affected the filtration rate of Katelysia. Under total darkness treatment, the clams opened their valves and extended their siphons. Hence, there was highest ingestion of algae or filtration in total darkness which showed to be the optimum condition to stimulate or promote feeding. In the algal species preference experiment, the food used were either Isochrysis galbana, Chaetoceros calcitrans , or a mixture of both. Results showed that I. galbana had the highest number of cells ingested by the clams and removed from suspension. This is considered to be the preferred algal species (F=0.119713) followed by a mixture of both, and lowest on the treatment where C. calcitrans was used as food. The preference of the clam on Isochrysis galbana over Chaetoceros calcitrans could be its smaller size based on dry weight.
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    Survival and metamorphosis of the mud crab Scylla tranquebarica larvae fed with Brachionus plicatilis and Artemia nauplii
    Ballescas, Ella Anne M. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2004-03)
    Despite the growing corpus of research on cultural nationalism, the state's role in producing cultural nationalism in a post-colonial and non-western setting and the phenomena from a bottom-up perspective continues to be little explored. This study examines the conditions under which national political leaders pursued policies to protect the cultural heritage of the country's indigenous cultural communities for the aims of political nationalism. From a top- down perspective, the study looks at the context, intent, content, state's implementation and caveats of the Indigenous Peoples Rights Act of 1997. While from the bottom-up perspective, the study looks at how the Bantoanon indigenous community mobilizes and organizes to navigate through state bureaucracy and ‘reappropriate’ the state's nationalism to meet their cultural goals. To examine the phenomena, the study on the textual analysis of existing written primary and secondary sources supplemented with oral interviews of key informants and a review of available literature. It finds that at the national level, political motives partly animated the support of political leaders for indigenous cultural heritage protection policies; that the state used heritage protection policies to pursue its political purposes; and that the support for political leaders for indigenous cultural heritage protection policies was premised on the condition that it did not interfere with the state's interests and diminish the state's rights. While at the Bantoanon indigenous cultural communities level, it finds that despite the caveats embedded in the country's heritage protection policies, the indigenous cultural community could mobilize and assert its rights, thus enabling it to ‘reappropriate’ the state's political institutions to meet its own cultural objectives. This thesis, therefore, argues that the relationship between the two parties under IPRA is mutually beneficial, with both the state and indigenous cultural communities finding some utility in the law.
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    Comparison of the length-weight relationship between starved and fed Scylla tranquebarica crablets
    Arroyo. Ritchel B. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2003-04)
    This study aimed to determine the length-weight as well as the width-weight relationships of the Scylla tranquebarica crablets when starved and fed during the intermolt and premolt stages. Molt stages were identified and then the crablets were subjected to feeding or starvation for 36 days. Regression analysis showed the length-weight relationship of the Scylla tranquebarica crablets, including carapace length, carapace width, and body weight when fed and starved. Regression lines for each category differed from one another. Results showed that the fed crablets in intermolt and premolt stages showed greater body weight gain per unit carapace length and carapace width. The intermolt fed gave the highest weight gain per unit length and unit width among the treatments. Equations for interconversions of length and weight and for length and width are reported for the premolt and intermolt stages when fed and starved.
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    Effect of salinity on the embryonic development of Portunus pelagicus and Charybdis feriatus eggs
    Alba, Kristine Margaret A. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2003-03)
    The effect of salinity on the embryonic development of Portunus pelagicus and Charybdis feriatus was studied. The five different salinity levels used were 15 ppt, 25 ppt, 35 ppt, 45 ppt, and control (33-35 ppt) to compare their effect on the embryonic development of both species. One thousand newly spawned crab eggs were incubated in vitro in 4-L Nalgene fiberglass containers with 3-L of water at different salinity levels. Mild aeration that allows movement of eggs within the water column was provided. There were three replicates per treatment. Embryonic development of eggs (30 eggs were taken in every salinity level) was monitored daily up to hatching. The newly hatched larvae were then collected and counted. Results showed that during the incubation period, the most advanced stage of embryonic development for Portunus pelagicus was at 33-35 ppt and for Charybdis feriatus was at 35 ppt. There was normal embryonic development and hatching at 35 ppt, 45 ppt, and control (33-35 ppt) for Portunus pelagicus and at 15 ppt, 25 ppt, 35 ppt, 45 ppt, and control (33-35 ppt) for Charybdis feriatus. Eggs that were incubated at 15 ppt and 25 ppt for Portunus pelagicus died. There was normal embryonic development in both species when incubated at 45 ppt. Hatching rate for Portunus pelagicus at control (33-35 ppt) was 34.1 %, at 35 ppt was 16.1 %, and at 45 ppt was 5.8 %. Hatching rate for Charybdis feriatus at 35 ppt was 52.5 %, at control (33-35 ppt) was 21.2 %, at 45 ppt was 12.8 %, at 25 ppt was 6.7 %, and at 15 ppt was 0.3 %. To summarize, embryo of Charybdis feriatus eggs can withstand a wider range of salinity: from a low salinity of 15 ppt to a high salinity of 45 ppt, that makes them a euryhaline species. On the other hand, Portunus pelagicus cannot support embryonic development at lower salinities of 15 and 25 ppt that makes them a stenohaline species.
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    Ingestion rate of Charybdis feriatus zoea on Brachionus and Artemia nauplii
    Abarca, Jinky G. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2003-04)
    A study was conducted to determine if presence of Brachionus will affect ingestion of Charybdis feriatus larvae on the Artemia and to find out the rate of ingestion with increasing density of Artemia. The experiment was conducted using 10-ml capacity vials filled with 6 ml of seawater (26-30 ppt). Increasing densities of Artemia were prepared (0.5, 2.5, 5.0, 10.0, and 20 ind/ml). In one set-up, Brachionus (15 ind/ml) was added. In another set, Brachionus was absent. Another set-up for Artemia with and without Brachionus was prepared but without Charybdis feriatus larvae which served as the control. There were five replicates per treatment. The amount of food prey (Brachionus and Artemia) ingested is determined after 24 hours of feeding on the first day of every zoeal stage (Zl, Z2, Z3, Z4, and Z5). The number of prey ingested by the crab larvae was then calculated. The prey organisms left in containers were then examined under the microscope for missing body parts. The results showed a trend of increasing ingestion rate with increasing Artemia density. This is observed both in treatments with and without Brachionus. The ingestion rate of C. feriatus larvae on the rotifer Brachionus plicatilis showed no trend. However, in zoea 1, there was a trend of increasing ingestion on Brachionus as the feeding density increases. And in zoea 5, it was seen that there is decreasing ingestion on Brachionus as the feeding density increases. There is a trend of increasing ingestion rate on Artemia nauplii as the Charybdis feriatus larvae grow from zoea 1 to zoea 5. There is also a trend of increasing number of observed Artemia with missing body parts as the Charybdis feriatus larvae grow from zoea 1 to number of zoea 5. In addition, there is an increasing number of observed Artemia naupliii with body parts partially ingested as feeding density increases. The presence or absence of Brachionus shows no significant effect on the ingestion on Artemia at low feeding densities (0.5, 2.5, 5 and 10 ind/ml) in all zoeal stages. However, at high feeding densities (20 ind/ml) the ingestion on Artemia is significantly different as seen is zoeal stage 1, 3 and 4.