The Effect of Water Quality on Aquaculture Productivity in Estuaries of Ampara District, Sri Lanka

Abstract

The coastal region of the Ampara district of Sri Lanka has a considerable number of perineal and seasonal estuaries which are poorly used for aquaculture. The reason they are not being used in aquaculture is the lack of awareness and inadequate information on the water quality parameters of these estuaries. Thus, the research has focused on investigating the water quality parameters of brackish waters in the Ampara district of Sri Lanka, with particular emphasis on their suitability for aquaculture. Water temperature, dissolved oxygen (DO), water and soil pH, salinity, conductivity, and total dissolved solids of the available estuaries or coastal wetlands in the Ampara district were investigated to assess the sites suitable for aquaculture for a full year from January to December 2018. Ambient temperature and precipitation were also recorded over the course of the year. The annual differences between the maximum and minimum level of water temperature, salinity, pH, specific conductivity, total dissolved solids, DO, and soil pH were 24.2 - 36.2ºC, 0.9- 38.2 ppt, 6.2 - 8.9, 55.5 - 62870 µs/cm, 35.5 - 37800 mg/L, 3.2 - 13.4 mg/L, and 4.0 - 7.2 respectively for the whole year of 2018. The water quality parameters investigated in the full year indicate that the culture of brackish water shrimps would be suitable in Arugam lagoon (salinity, 17.1±3.3ppt) and Komari river mouth area (salinity, 21.4±8.4ppt), and culture of freshwater fish would be better in Oluvil (5.3±3.5ppt), Addalaichenai- Konawatte and River mouth (4.1±1.2ppt), Periyamuhathuwaram (3.2±1.2ppt), and Urani lagoon (5.1±3.0ppt) in all year long. As the seasonal lagoon of Sainthamaruthu (9.8±2.6) is unpredictable and recorded with highly variable water quality parameters, it would be very risky to culture the shrimps and may be suitable for euryhaline fish culture. The Sinnamuhathuwaram lagoon (9.3±3.9 ppt) is suitable for euryhaline fish farming during the period between November and March, while it is suitable for shrimp cultivation from April to October. Pottuvil Lagoon in Kottukkal would be suitable for freshwater fish farming from November to April, and for shrimp farming from April to October. Our study concluded that the lagoons of Komari- II and Arugambay are the ideal sites for culturing shrimp in all year long.