Browsing by Author "Dejager, T."

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    Study of water quality changes and growth of cultured edible oysters (Crassostrea madrasensis), culture sites at Gagewadiya and Kandakuliya in Puttlam district
    (Uva Wellassa University of Sri Lanka, 2015) Wijayananda, H.I.; Rajapaksha, R.M.G.N.; Liyanage, N.P.P.; Kithsiri, H.M.P.; Corea, S.; Rupika, G.R.H.; Fernando, U.; Dejager, T.
    Global bivalve production from aquaculture has consistently increased over the years. Sri Lanka is a country which has vast natural resources and suitable environmental conditions for aquaculture. Therefore it has a great potential for develop and contribute to national fish and shellfish production. Although the bivalve industry is highly developed industry in East Asian region finfish and shellfish, specially mollusk and sea cucumbers cultures are at very initial stage in Sri Lanka (Samarasundera, 2010).Sustainable utilization of unexploited high demand finfish and shellfish species are a good alternative to develop the industry. Oysters are nutritious, still unexploited fishery resources in Sri Lanka. Which has good export demand worldwide. Although Sri Lanka have required resources naturally to uplift the industry in large scale, lack of information, limited supply of seeds and lack of trained personals are act as major constraints (FAO, 2006). The success of bivalve culture greatly depends on suitable environmental factors that ensure both optimal growth and quality as well as ensure food safety (FAO, 2006). Kandakuliya and Gagewadiya areas are blessed with natural oyster resources but which are not used commercial scale at present. Therefore the two locations have significant possibility to conduct oyster culture in large scale which providing self-employment opportunities for fisher communities. The study of water quality changes and growth of edible oysters (Crassostrea madrasensis) culture, sites at Gagewadiya and Kandakuliya in Puttlam district was carried out to investigate the possibility of establish these culture in commercial scale. Methodology The research project was conducted in two experimental sites (Gagewadiya and Kandakuliya), locates in Puttlam district, Sri Lanka. Field data were collected during October 2013 to July 2014from pre- establish two experimental culture sites. There were four sampling points in each site separately K1, K2,K3, K4in Kandakuliya and G1, G2, G3, G4in Gagewadiya. Water quality data, growth data and phytoplankton data were collected each site separately. Water quality and phytoplankton data were collected twice a month, and growth data were collected once a month during the studied period. Temperature, pH, salinity, transparency were recorded as onsite measurements. Further analysis were conducted for nitrite, nitrate, phosphate and ammonia using DR-4000U spectrophotometer according to standard procedures of Parsons et al., 1984. Unionized ammonia levels were calculated using total ammonia levels. Phytoplankton samples were collected using phytoplankton net (50 µm mesh size).The samples were examined under light microscope and identified to genus level using identification keys (Newell and Newell, 1963; Rebert, 2003; Swadling, 2008; Verlencar and Somshekar, 2004).Length (distance between the end of umbo and the ventral shell margin) and width (length at the widest axis of the body) were taken as growth parameters. Twenty five C. madrasensis organisms were used to take measurements from each site separately, for the growth study. Both primary and secondary data were used to analysis. Secondary data were taken from IDRC oyster research and culture programme. Minitab 16 statistical package was used to data analysis. All data were analyzed statistically using one way ANOVA (Turkey test) for all selected locations. Person product movement correlation coefficient analysis was done between water quality parameters and growth of oysters to find whether there were significant relationship between those variables.