UPV Digital RepositoryUPV-DRUniversity of the Philippines Visayas
 

Undergraduate Theses

Permanent URI for this collectionhttps://hdl.handle.net/20.500.14583/13

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    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.
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    Some aspects of the reproductive biology of the telescope snail Telescopium telescopium (Linne) in milkfish ponds
    Arboleda, Ianthe Anfone (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 1999-04)
    Telescopium telescopium, a mudsnail locally known as “bagungon” , is important since at high densities it may become a pest in fish aquaculture ponds. Knowledge of its reproductive biology is necessary in order to properly manage this resource. Thus, this study aimed to 1) describe histologically the different gonadal stages of T. telescopium, 2) determine the reproductive cycle and spawning peaks of the species based on the gonadosomatic index (GSI), and 3) determine the size at sexual maturity of the species in the milkfish ponds. Monthly samples were collected from May 1997 to March 1998 (except for September 1997) from brackishwater milkfish ponds. Shell length and GSI for each snail was measured. The gonads were processed histologically after all sampling activities were concluded. Histological examination showed the following gonadal stages: immature, developing (male and female), ripe (male and female), spawning ( female), and redeveloping ( female). The GSI profile showed no marked fluctuations, indicating partial and continuous spawning. However, the mean monthly GSI values may have been greatly affected by the harvesting of the snails done in the milkfish ponds and the presence of immature gonads with weights that could not be determined using the available balance (weights<0.01 g). The smallest observed mature male had a shell length of 43.32 mm, and the smallest observed mature female had a shell length of 36.42 mm.