Browsing by Author "Jayasiri, H.B."

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    Effect of Nitrogen Sources on Growth Performance of Marine Microalgae Nannochloropsis sp.
    (Uva Wellassa University of Sri Lanka, 2019-02) Kondasinghe, K.P.R.S.; Jayasiri, H.B.; Mallawaarachchi, J.; Guruge, K.P.G.K.P.; Thilakarathna, E.P.D.N.
    Nannochloropsis sp. is a marine micro alga immensely valuable for aquaculture and food industry as they are rich sources of essential fatty acids, pigments, amino acids and vitamins. Present study was conducted to identify the effect of nitrogen sources on their growth and nutrient content in the cells. For the study, F/2 culture media was used as media in control culture which contains NaNO3 as the source of nitrogen. The F/2 culture media was prepared by using KNO3 (9 g l-1), CH4N2O (Urea) (27 g l-1) and NH4Cl (47.3 g l-1) as the sources of nitrogen in the culture media. Algae cultures were prepared in triplicates for all treatments and cultivated under indoor condition, maintaining the 27 oC of constant temperature and 25ppt of salinity with a continuous aeration. The results of ten days culture revealed that there was no significant difference for cell density with the time for all treatments (Two-way ANOVA: p>0.05). However, significant difference was found for chlorophyll-a nitrate and nitrite content which are produced by Nannochloropsis sp. (p<0.05). The significantly highest chlorophyll-a, nitrate and nitrite content were reported in the F/2 culture media with urea than that of other culture media treated with potassium nitrate and ammonium chloride. The Urea can be recommended as a more effective source of nitrogen for F/2 culture media to obtain high chlorophyll-a, nitrate and nitrite content for Nannochloropsis sp. culture. This study provides baseline information about the appropriate nitrogen sources which can elevate the higher productivity of Nannochloropsis sp.
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    Quantitative Assessment of Microplastics in Surface Water of West Coast — off Colombo, Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2018) Athawuda, A.M.G.A.D.; Jayasiri, H.B.; Jayamanne, S.C.; Weerakoon, W.R.W.M.A.P.; Guruge, K.P.G K.P.; Thushari, G.G.N.
    Contamination of water with plastic litter including microplastics is a serious environmental issue. This study addressed morphological identification and quantification of microplastics (1-5 mm) with spatial variability in surface waters of 7 sites; Uswetakeiyawa, Kerawalapitiya, Dikowita, Portcity, Kollupitiya, Bambalapitiya and Wellawatta along west coast - off Colombo during AugustNovember 2017. Marine floating litter was collected, by towing a manta net, mesh size of 300 𝜇m and microplastics were recovered from samples using visual observation. Microplastics were confirmed by hot needle test and categorized into 4 classes based on color: black, white, colored and transparent. Sorted plastics were quantified as number and weight. Total microplastic density does not significantly change with geographical location, as distribution of microplastics has been affected by oceanic waves and winds (p > 0.05). Rough sea state causes mixing of surface microplastics, and altering distribution pattern over the sites during sampling period. Overall mean density of micro plastics was 0.33 ± 0.13 mg m-3 and 0.39 ± 0.05 No M-3 by weight and number of items respectively. Density of white colored microplastics significantly varied spatially, due to site-specific anthropogenic activities (p < 0.05). Highest number of white microplastics accumulated in water samples of Uswetakeiyawa (0.35 ± 0.06 No m-3), by land based sources of tourism and recreational activities. According to results, all study sites are affected by plastic pollution and cause significant health risk on coastal biota. Microplastic contamination level in surface waters acts as a key indicator on high pollution level in west coast. Site specific management measures are suggested to mitigate microplastic pollution. Frequent estimations of microplastic density in surface water are recommended throughout year in west coast of Sri Lanka. This study provides baseline information on microplastics level in surface water of west coast.