Research Symposium-2013

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Browsing Research Symposium-2013 by Subject "Aquaculture"

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    Application of GIS to Identify Potential Areas for Aquaculture in Badulla District in Uva Province
    (Uva Wellassa University of Sri Lanka, 2013) Sandamali, M.A.N.; Rathnayake, R.M.C.W.M.; Liyanage, N.P.P.; Jayamanne, S.C.
    Aquaculture is farming aquatic organisms including fish, mollusks, crustaceans and aquatic plants (FAO, 1990). The main intent of the present study is to highlight the role Geographic Information System (GIS) in identifying potential areas for aquaculture in Badulla district. The study was carried out in Badulla district in Sri Lanka by the geographical coordinates of longitude 80 .45 to 81 .15. Latitude 6 .34 to 7 .18. Data have been collected from secondary sources and used to generate maps to identify fresh water bodies in Badulla district. Map of seasonal tanks, reservoirs and tanks, stream network and rivers of Badulla district were developed. Water availability (proximity to rivers), soil texture, soil pH, rainfall, temperature and topography (slope, elevation) and land use factors were considered to identify potential areas for aquaculture (pond culture). Protected areas are considered as constraints. Water availability, soil texture, soil pH, slope, elevation, rainfall, temperature, land use/ land cover thematic layers were created using ArcGIS 10.1 software. All these thematic layers have been assigned the weights according to their relative influence on pond construction using Analytic Hierarchy Process (AHP) and GIS approach. Finally, all thematic layers have been integrated in a ArcGIS 10.1 environment to generate an aquaculture potential map. Thus, four aquaculture potential areas have been Identified, viz. “Most suitable”, “Suitable”, “Fairly suitable”, “Unsuitable”. The north part of the Badulla district is identified as most suitable and the southern part of the Badulla district is identified fairly and unsuitable for aquaculture in Badulla district. Methodology Data collection: Secondary data were collected from secondary sources. GIS analysis: reservoirs and tanks, Rivers, Stream network of Badulla district were digitized using Arc View 3.1 software. GPS coordinates of seasonal tanks were stored & developed a map using ArcGIS 10.1 software to identify fresh water resources in Badulla district and all data were stored in ArcGIS 10.1 environment and factor thematic layers were generated to identify potential areas for aquaculture. Analytic Hierarchy Process (AHP) - AHP is a multi-objective, multi criteria decision making approach that employs a pair wise comparison procedure to arrive at a scale of preference among a set of alternatives (Dai et al., 2001). Thematic layers were evaluated using scores and each weighted according to their relative importance on the aquaculture using Analytic Hierarchy Process (AHP) and GIS approach. Map Generation -Each thematic layer was evaluated using the scores that were obtained according to the weighted linear combination in ArcGIS 10.1 environment. Vector format was converted to raster format. To reject the constraints the final result was multiplied by absolute constraints. The protected areas were allocated a zero score. Finally, the potential areas for aquaculture map was created and categorized into four levels: Most suitable, Suitable, Fairly suitable, Unsuitable based on the total scores obtained from the weighted linear combination.
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    A Preliminary Study on the Best pH Value of Water to Increase the Quality of Echinodorus Bleheri
    (Uva Wellassa University of Sri Lanka, 2013) Withanage, W.A.S.; Bambaranda, B.V.A.S.M.; Jayamanne, S.C.; Fernando, M.A.G.C.
    The Aquatic plant export industry of Sri Lanka has been developing rapidly. This industry requires a continuous supply of high quality plants. Echinodorus bleheri is one of the highest demanded aquatic plants in export market. Aquatic plants have adapted to life in water with a specific pH, Temperature, Electrical conductivity and may suffer from even a slight change. High quality plants can be supplied with in a short time period by finding the best pH value of water. In the world of plants each plant species is perfectly adapted to a certain pH range of the soil or water. Aquatic plant hobbyists are usually familiar with the different pH requirements of various plants and regulate the pH of water appropriately. Hydroponics is proved to have several advantages over soil gardening. The growth rate on a hydroponic plant is 30-50 percent faster than a soil plant. A nutrient solution for hydroponic systems is an aqueous solution containing mainly inorganic ions from soluble salts of essential elements for higher plants. Eventually, some organic compounds such as iron chelates may be present (Steiner, 1968). Changing the pH of a nutrient solution affects its composition, elemental speciation and bioavailability. An important feature of the nutrient solutions is that they must contain the ions in solution and in chemical forms that can be absorbed by plants, so in hydroponic systems the plant productivity is closely related with to nutrient uptake and the pH regulation (Marschner, 1995). Each nutrient shows differential responses to changes in pH of the nutrient solution. The proper pH values of nutrient solution for the development of crops, lies between 5.5 and 6.5. Plants need the right combination of nutrients to live, grow and reproduce. When plants suffer from malnutrition, they show symptoms of being unhealthy. Too little or too much of any one nutrient can cause problems. The main objective of the present study is to find out the best pH value of water to increase the quality of Echinodorus bleheri. Methodology This experiment was conducted under green house condition with 80% shade at Ruvini Aqua plants Lanka (pvt) Ltd, Koralawella, Moratuwa. Hundred and eighty Echinodorus bleheri plant pots(containing four plants in each pot) were used for the experiment. Experimental design was Complete Randomized Design. Fifteen Styrofoam boxes (46 cm×39.5 cm×19.5 cm) were used to plant them. HANNA (HI98107) portable digital pH meter was used to measure pH and HANNA portable digital EC meter (HI 98303) was used to measure Electrical Conductivity of water. Two months aged 180 Echinodorus bleheri plant pots were randomly selected and uprooted from culture tanks. Plant pots were washed thoroughly after removing sand and other objects. Randomly selected 12 plant pots were assigned in to a tank and measure the wet weight of 12 plant pots. Plant pots were planted in 15 Styrofoam boxes. Bottoms of the Styrofoam boxes were covered by black polythene sheets to prevent the algal growth. Placement of Styrofoam boxes were decided by lottery method. Five different pH solutions were used for the experiment as 6.0, 6.5, 7.0 (control), 7.5 and 8.0. Six grams of Albert solution was dissolved in 7 l of water and filtered the solution using a muslin cloth. pH of the solution was measured. NaOH or HCl was added drop wise until required pH value achieved and maintained the electrical conductivity 1000-1500 µs level. Prepared pH solutions were kept for 1 hour to see the fluctuations. pH solutions were poured in to tanks. After 2 days pH solutions of each tank were removed using manual squeeze water changer pump and filled the solutions again week, plant pots were uprooted from Styrofoam boxes and measured the wet weight of each replicate (12 plant pots). Total lengths of plants were measured using a tape weekly. Number of leaves was counted weekly. Wet weight of each replicate (12 plant pots) was measured before starting the experiment and at the end of the experiment. Data obtained from the experiment were analyzed by Microsoft Word. Treatment significances and significance among individual treatment levels were analyzed using one way analysis of variance (ANOVA).