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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1998 - 19992

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Adviser: search.filters.advisor.Del Norte-Campos, Annabelle G.C.Degree: search.filters.degree.Bachelor of Science in Biology

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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.
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    Growth of the telescope snail, Telescopium telescopium (Linne) in brackishwater ponds
    Apistar, Jobert H. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines, 1998-04)
    Samples of T. telescopium were collected every month, from April to October 1997 for 6 months, in brackishwater ponds. Allometric relationships were defined by comparing shell length with shell width, as well as various body weight proportions including total weight with shell, total volume with shell, visceral weight and visceral volume. A total of 5 cohorts with growth rates ranging from 0.45 - 0.67 mm-day- were observed using the Bhattacharya analysis. A high mean growth rate of 0.56 mm-day- (sd = 0.07, n= 5) was estimated by joining the modes of the cohorts between successive sampling months. Low inverse correlations were observed between mean shell length and various environmental parameters (i.e. salinity, air temperature, water temperature and organic matter content) possibly explained by the species' environmental adaptations. On the other hand significant correlation was observed between mean shell length and density, indicating the possible role of overcrowding in these habitats.