Abstract:To intensify the production of edible oyster in Sri Lanka in the future it is essential to analyse the status of the present culture practices. The present study was carried out to investigate the growth and health of cultured edible oyster, Crassostrea madrasensis in relation to the prevailing water quality parameters and external fouling in a small-scale, commercial farm located in the Panadura estuary, Sri Lanka.The mean growth rate in shell length and shell width varied between 0.06 ± 0.01 mm and 2.19 ± 0.09 mm and between 0.02 ± 0.02 and 2.11 ± 0.39 mm per week, respectively. There were positive significant relationships between the growth rate in shell width and salinity, as well as the conductivity of culture water (p < 0.05). Mean total dissolved solids in culture water had a positive significant relationship to the growth rate of oysters in shell length (p < 0.05). External fouling organisms that grew on the outer shell surface caused significant reduction in growth rate as well as the weight gain of cultured C. madrasensis (p < 0.05).Histological sections of the gills, mantle, digestive gland and digestive tract of oysters exhibited structures similar to plasmodia of a haplosporidian parasite, which reached the stage of rupturing during the period of low salinity. C. madrasensis could tolerate the low salinity, ranging from 0 gL -1 to 6.0 gL -1 with 83.0 ± 2.47 % survival; the highest mortality recorded during the period with low salinity in culture water was 15.00 ± 2.50 %.
General objective: To estimate the seroprevalence of HIV, hepatitis B and syphilis among remote tea estate youths. Specific objectives: To explore the sexual health knowledge and their sexual behaviours Methodology: A descriptive cross sectional survey of 400 remote tea estate workers, aged between 18-24 years were carried out in 5 tea estates in Kotagala-Thalawakele Health division. Systematically selected random sample of youth participated in; first self answered questionnaire, then an interview and finally serological testing of HIV, hepatitis B and syphilis. Results: The sample consisted of 188 males (47%) and 212 females (53%). One hundred and forty six (36.5%) were married. The mean age of sexual debut for males was 12.56 (SD=1.88) and for females it was 16.21yrs (SD= 1.79). Eighty six percent of males had a homosexual experience and 63% had more than one same sex partner. Peers were their main source of knowledge (59%) and most reliable person to discuss sexuality (55%). The large majority of the participants (n=324, 81.25%) never heard of a disease called AIDS. Only 3.25% (n=13) of respondents had ever heard of diseases called sexually transmitted infections. Conclusion: Irrespective of very low sero prevalence of HIV, hepatitis and syphilis sexual health services are not sufficient to meet the needs of youth in the plantations and available services are not being delivered appropriately. A comprehensive, integrated sexual health service is needed for the youth and adolescents in the estate sector.
The food and feeding studies of fish are useful to explore the possibilities of using them for various purposes such as aquaculture and biological control of problematic organisms. In the current study feeding patterns and diet composition of Aplocheilus parvus (E: Killi fish/Drawft panchax), a common surface feeding predator inhabiting freshwater systems were explored. A. parvus was collected from an abandoned brick pit in Pannala in 2012. Twelve fish were caught every two hours for 24 hours. Plankton net was used to obtain a representative sample of food items present in the system. Gut fullness, total and standard length of fish, total weight and gut weight were determined and using copepod as an arbitrary unit, total numbers of food items of individual fishes were estimated. The time at which active feeding occurred was established from total food particle amount and relative gut weight. Diet of A. parvus mainly consisted of adult or larval stages of insects and copepods. Also, gut had a higher fullness in day time compared to night. The peak gut fullness occurred during 1630 in males whilst females had the peak gut fullness at 1230. Copepods were detected mostly during late morning, whilst insect parts and coleopterans were present in all time periods. Main food items detected in the environment in descending order of abundance were copepods, filamentous algae and insects. This study demonstrated that A. parvus selectively preys on insects compared to other aquatic food sources during day time.
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