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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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    Gonadal maturation Stages of Pinkfingered Vinegar Crab Episesarma chengtongense (Serene and Soh 1967) from Capiz, Philippines
    Barredo, Elilyn Farrah Belle B. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2015-06)
    The pink-fingered vinegar crab Episesarma chengtongense is a growing fishery resource in the mangrove areas of the Philippines and may have potential for aquaculture and stock enhancement. To determine the gonadal maturation stages for both male and female for this species, a study was conducted from February to May 2015 of the pink-fingered crab from Capiz, Philippines. The determination of the gonadal maturation stages was based on the gross morphology and histological characteristics of the male and female gonads. In both sexes, gonad activity occurred throughout the study duration but for females, the peak egg bearing month was in May (87%). Body sizes of ovierous females were from 31.9 - 42.3 mm (CW). The greatest prevalence of ovigerous females was in the size range of 35-39 mm CW; the lowest percentage at 40-44 mm CW. Male crabs with mature testes were consistently high (70- 100%) in the four months duration of the study. The smallest female carrying eggs was 31.9 mm CW. Four stages of ovarian maturation were identified namely: developing (Stage II) with a yellow colored gonad, ripe (Stage III) with orange colored gonad, mature (Stage IV) with brown colored gonad and spent (Stage V) with light brown colored gonad. Two stages of male gondal maturation were identified namely immature (Stage I) with translucent to off white testes and mature.(Stage II) with creamy white testes.