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    Reproductive biology of coconut crab Birgus latro (LINNAEUS 1767) from Antique, Western Visayas, Philippines
    Alberca, Pavi Jewime O. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2016-06)
    The coconut crabs Birgus latro continue to decline globally and are now considered as an endangered species. In order to prevent further depletion of the species, much effort must be placed on implementing municipal ordinances such as seasonal closures and minimum legal size limits. This study aimed to monitor the breeding cycle of the Birgus latro from the islands of Sibolon and Maniquin. Antique. Philippines using macroscopic and microscopic techniques. A minimum of ten crabs were collected every month for six months (Aug. 2015 - Jan. 2016). The crab samples were examined based on the morphological and histological appearance of the gonads. The body weight, thoracic length (TL). cephalothoracic length, carapace width, pleonal expansion, gonad weight and hepatopancreas weight were measured. The gonadosomatic index (GSI), hepatosomatic index (HSI). pleonal expansion index (PEI) and gonad index (GI) were calculated. The results revealed two stages of development for both the male and female B. latro. The testicular stages were a) maturing stage - creamy white with the presence of spermatogonia, spermatids and spermatozoa; b) mature stage - creamy white and larger with the presence of the spermatozoa only. The ovarian stages were a) maturing stage - light yellow with the presence of oogonia, endogenous and exogenous vitellogenic oocytes and follicle cells: b) mature stage - reddish brown and larger with the presence of the fully mature oocytes. The smallest sexually mature crab for the male was 28 mm TL and for the female was 32 mm TL. The mature testes were observed all throughout sampling period, while the mature ovaries were only in August, September and October. The occurrence of the male B. latro was higher than the females. In males, the GSI and GI were directly proportional to the developmental stages. The HSI was inversely proportional. while the PEI showed no relationship. In females, the GSI. HSI. PEI and GI showed a direct relationship with the stages of development.
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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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    Effect of salinity on survival and growth of Scylla olivacea crablets
    Andres, 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.
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    Larval rearing of Scylla serrata Forskal: The effect of Artemia salina and Brachionus plicatilis as food on the growth and survival of zoea
    Apote, Ma. Noemi G. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 1996-11)
    A study was conducted to find out tile effects of Artemia, Brachionus and a combination of Anemia and Brachionus as food on the survival of mudcrab Scylla serrata Forskal zoea and the ability of the zoea to metamorphose to megalopa stage. The study composed of three experiments. Each experiment lasted for 21 days. Results showed highest mean percent survival (66.7±2.03) on zoea fed with a combination of Anemia and Brachionus at a feeding density of 5 individuals/ml each. When the density of Brachionus was increased from 5 individuals/ml to 12 individuals/ml in the combination diet, there was an increase in the survival of the zoea to 68.9±2.41. Highest metamorphosis from zoea to megalopa was also obtained on those fed with a combination of Anemia and Brachionus. This combination diet also gave the shortest number of days for the zoea to metamorphose to the next stage which also resulted to the least number of days for megalopa production to start. The study also revealed that larvae ted with a combination of Anemia and Brachionus reared at 30 ppt salinity got high survival on the first three days of culture, however starting on the 4th day up to the 15th day of culture, those reared at 28 ppt obtained higher survival although not statistically different from the other salinities tested.
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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.