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Histomorphological study of the gonads of Pholas orientalis
Beluso, Michelle O. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 1994-04)
A total of five "diwal", Pholas orientalis, two of which wore obtained from Hinigaran, Neg. Occ. on January 1995 and three from Lanas, Barotac Nuevo on February 1994, were examined for the histomorphological study of the gonads of the species. Among the five samples, two were males and three were females. No hermaphrodites were encountered. Macroscopical examination showed that the gonads were diffused in the visceral mass extending from the anterior to the posterior part of the animal. The gonads were arborescent in form and creamy in color. No external sexual differences were observed. Histological examination showed that male and female gonads were scattered in the visceral mass and concentrate most around the stomach. Male and female gonads consist of follicles which were lobular and embedded in the connective tissues. Three sexual maturity stages were observed among the five specimens, which are the late active, ripe, and partially spent stages. During the late active stages in both male arid female gonads, developing gametes (spermatocytes and young oocytes, respectively) are attached to the follicular wall with maturing gametes lying free in the follicular lumen. At the ripe stage, male gonads showed mature sperms free in the follicle lumen with sperm tails radiating into the center of the lumen. In females, ripe oocytes are free in the follicle lumen with some maturing oocytes still attached to the folli- cular wall by a slender stalk. Partially spent stage was observed only in females. Spent gonads showed spaces in ovarian follicles due to loss of ova through spawning (1938). Since there is a growing demand for "diwal", interest on this species had picked up lately. One of the earliest studies on P. orientalis was the study on the "diwal" fishery in Neg. Occ. conducted by Ablan (1938). The larval biology and mariculture of the angelwing clam, Cyrtopleura cos- tata, were studied by Gustafson, et al. (1991) and investigations into spawning and hatchery technique for P. orientalis are underway (Gustafson, et al., 1991). Studies on the biology of P. orientalis are few and in fact no literature regarding reproductive biology of the species was obtained. Thus, this study was carried out with the following objectives: (1) to determine the location of the gonads in the visceral mass of P. orientalis, (2) to describe the histomorphology of the gonads, and (3) to differentiate the gonadal conditions histologically
Community structure of riverine mangrove stand in Brgy. Talokgangan, Municipality of Banate, Iloilo Province
Belaño, Keith Dominador L. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2001-04)
The community structure of riverine mangrove stand in Brgy. Talokgangan, Municipality of Banate, Iloilo was studied. Ten “true” mangrove species representing seven families were encountered in the “mangals” of Balandra creek community in Brgy. Talokgangan. They were Avicennia marina, Avicennia lanata and Avicennia alba representing Family Avicenniaceae; Rhizophora apiculata and Rhizophora mucronata under Family Rhizophoraceae; Sonneratia alba of the Family Sonneratiaceae; Excoecaria agallocha under Family Euphorbiaceae; Camptostemon philippinense of the Family Bombacaceae; one from the Family Meliaceae namely Xylocarpus granatum, and Family Palmae represented by Nypa fruticans. Stand Basal Area was computed highest in Station 1 with 10.22 m2/ha. Station 1 was also the densest among the four stations with a density value of 2533 trees/ha. In terms of data evaluated per zone, the landward zone has a Stand Basal Area of 10.87 m2/ha which is slightly higher than the middle and riverward zones. The middle zone, however, was found to be the densest with 1850 trees/ha. The most dominant station was Station 1 with the highest Index of Dominance of 0.3319, however, was found to be the least diverse station. The highest Index of Diversity was computed in Stations 2 and 3, with diversity indices of 0.8976 and 0.8989 respectively. Avicennia marina was found common in all stations and the most dominant, making it the most important mangrove species. They were found to occupy the whole site, growing abundantly in wide range of conditions from areas frequently inundated by tidal flow in Station 1 to the firmer muddy substratum in the back mangrove areas. Rhizophora apiculata and Rhizophora mucronata was observed to occupy waterlogged soil conditions. Excoecaria agaliocha tend to flourish in firmer muddy substratum in open sites, whereas, Xylocarpus granatum was observed to occupy zones where salinity is lowest in areas rarely affected by tidal flow. Sonneratia alba and Camptostemon philippinense tend to grow in zones directly inundated by tidal flow.
A community study of mangroves in Brgy. Caliling, Cauayan, Negros Occidental
Barredo, Sherry Marie P. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2000-03)
The species distribution of the mangrove community in Brgy. Caliling, Cauayanz Negros Occidental was studied using the transect line plot method with three plots for each of four stations established. Both stations 1 and 4 were located landward, while stations 2 and 3 were located seaward. Community structure Is described in terms of the following parameters; basal area, number of trees per hectare, importance value, relative density, relative frequency, frequency of species and relative dominance. Variations in these parameters are correlated with physico-chemical factors such as the air, water and soil temperature, water depth, salinity and pH. Ten true species were found In the mangals of the coastal environment of Brgy. Caliling, Cauayan, Negros Occidental. They were Avicennia aiba, Avicennia Janata, Avicennia manna, Campostemon phiiHpinensis, Excoecaria agallocha, Osbomia octodonta, Nipa fruticans, Brugeria cylindrica, Rhizophora apiculata and R. mucronata. Standard Basal Area was highest in Station 3 with 7.54 m/ha. In terms of zonation, the landward zone was found to have the highest Stand Basal Area with 11.15 m/ha. Station 2 had the highest density value of 33.92 %, whereas in terms of zonation, both the middle and seaward zone had the density value of 36.20 %. Avicennia marina was found to be the most dominant species and was observed to occupy sites with hypersaline conditions, in silty clay to muddy substratum, which may or may not be inundated by tidal flow most of the time.
Determination of the fungal flora in the rearing water, eggs, larvae and post-larvae of Penaeus monodon in a large-scale hatchery system
Baes, Glanee F. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 1995-03)
The rearing water and homogenized. eggs, larvae, post-larvae of Penaeus monodon were taken front the large-scale hatchery system. These were counted, isolated and identified. Analysis was done by determining the mean, standard deviation and skewness of the data. The result showed that the skewness of the yeast and mold counts in the rearing water were 0.93 and 0.64, respectively 'while that in the homogenized samples were 0.92 and 1.09, respectively. These showed that the data were positively skewed, hence, fungi were greater in the early larval stages than in the later stages. The mean showed that yeast yielded greater counts as compared to the molds. Furthermore, rearing water have also higher fungal count than that of the homogenized prawns. The fungi identified were Aspergillus, Balanium, Bispora, Cladosporium and Phialomysis. In the study, the fungi identified were the normal mycoflora which did not adversely harm the prawn due to favorable hatchery conditions, there being no disease outbreak during the duration of the study.
Taxonomy and distribution of holothurians in selected sites within Panabolon Island, Guimaras
Bachoco, Raian Dennis (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2001-04)
This study mainly deals with the taxonomy and distribution of sub-tidal holothurians in 2 selected sites based on the predominant substrate and vegetation characteristics, within Panabolon Island. Sampling was done during low tides in the months of March and April 2001. A total of seven species in five genera belonging to families Synaptidae, Holothuriidae and Stichopodidae were recorded from the study area. The family Holothuriidae is the most common (4 species) of the three families. Synapta maculata is the most abundant species (33.33%) followed by Holothuria atra (27.27%) and Holothuria scabra (21.21%). Highest species diversity was observed in the coralline area with strong water movement while-densities are highest in areas with seagrass beds
The effect of different feeding schemes on mudcrab Scylla serrata larvae fed with Artemia salina
Bachoco, Anabelle M. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 1998-04)
The study on the effect of different feeding schemes of mudcrab Scylla serrata fed with Artemia salina was conducted to identify the zoeal stage of S. serrata where an addition of Artemia to the diet results to higher survival, shorter intermoult duration, higher growth index, and shorter metamorphosis to the megalopa stage. All treatments were fed with Brachionus at a density of 20 ind./ml. Results showed that larvae fed with Artemia from day 0 had consistently high percent survival and this is significantly higher compared to other treatments. This was followed by larvae fed with Artemia at day 3 and at day 6. However, statistical analysis showed that there is no significant difference between the two treatments. Significantly low percent survival was obtained on larvae fed with Artemia at day 9. Results also showed that larvae fed with Artemia at day 0 metamorphosed to megalopa stage after 18 days and obtained the shortest average intermoult duration of 3.6 days and highest growth index of 5 6. This was followed by larvae fed with Artemia at day 3, day 6, and day 9. Artemia has high nutritive value which contributed to high survival, shorter intermoult period, high growth index and shorter metamorphosis period up to the megalopa stage.
A study on spawning induction of Imbaw Anodontia edentula (Linne, 1758)
Bacaro, Teressa Mae D. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2008-03)
The mud clam, Anodontia edentula, was induced to spawn using extract from ripe and developing gonads. Clams responded to the spawning stimulus by extension of the foot, swelling and extension of the mantle, swirling of the whole body, rapid opening and closing of the valves, ejecting of white material from the excurrent siphon, and subsequent contraction of the adductor muscles. Successful spawning of all individuals occurred with the use of gonad extract. Developing homogenized extract was not as effective in inducing the broodstock to spawn. Gametes were released through the excurrent siphon located at the posterior end.
Effects of high and low protein diets on the gut evacuation rate of Tilapia nilotica
Andrada, Bryan Andrew S. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 1999-03)
Gut evacuation rate of young Nile tilapia, Tilapia nilotica fed commercial pelleted diets containing high or low protein diet were determined in the laboratory. The decline in gut fullness of the fish with time was examined at low and high protein diets. Two mathematical models were used to express the decline in gut fullness of the fish with time. Fish fed the low protein diet followed more closely the linear model while those fed the high protein diet followed the logarithmic model. The level of protein resulted in different gut evacuation rates (GER), expressed as coefficients b of the gut fullnesstime curve. GER values were higher in either linear or logarithmic models for fish fed low protein diet than for those fed high protein diet.
Diel feeding patterns of angelwing clam Pholas (Monothyra) orientales (Gmelin, 1970)
Alojepan, Marbe Joy L. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 1999-04)
Filtration rate of Pholas orientalis measured using the indirect suspension deletion method and monitored by direct algal cell counts. Phytoplankton Isochrysis galbana was used as food at an algal cell concentration of 2.5 x 103 cells ml ”'. Biological rhythms have been demonstrated in all animals and plants except bacteria. They control rhythmic patterns in behavior and physiology of a living organism. Biological rhythms, or oscillations, have a “period” that is measured from one arbitrary point or phase of the rhythm to the next occurrence of that phase. They are best demonstrated in a 24 h cycle or circadian cycle. There is a widely varying feeding activity in the 24h cycle of P. orientalis observed at a constant temperature of 27$C and hydrogen ion concentration of 35%o Like any other bivalves, P. orientalis has defined feeding periods equivalent to food uptake at 2400h-0300h. Such observation could be supported by a previous study by Corda stating that optimal feeding was obtained at total darkness. Periods of digestion occur shortly after the periods of feeding. P. orientalis when actively feeding were observed to have extended siphons, larger valve openings, and an inclination of 45. One primary external stimulus that affected filtration rate was the amount of light present. Biorhythms provide temporal information, such as the time of day or season of the year, which facilitates adaptation of the organism to internal or external environments.
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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