Browsing by Author "Shanuke, D.S."

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    Assessment of Macroalgae Diversity along the Economically Important Southern Coastal Zone of Sri Lanka during North East (NE) Monsoon Period
    (Uva Wellassa University of Sri Lanka, 2020) Wijethunga, H.N.S.; Silva, A.P.R.; Shanuke, D.S.; Abeygunawardana, A.P.; Senevirthna, J.D.M.; Bambaranda, B.V.A.S.M.; Thushari, G.G.N.; Liyanage, N.P.P.
    Southern coastal zone acts as a highly productive ecosystem with rich macroalgae diversity. However, limited scientific studies have been conducted on macroalgae diversity in the southern coastal belt of Sri Lanka. The current study is focused on the assessment of the intertidal, macroalgae diversity along this coastal belt. This study was conducted using systematic sampling technique along the intertidal zone at 12 selected regional coasts (Hambantota, Godawaya, Rekawa, Tangalle, Dickwella, Polhena, Mirissa, Weligama, Unawatuna, Galle Fort, Dodanduwa and Hikkaduwa) representing three districts (Hambantota, Matara, Galle) of the southern province during NE monsoon period (December 2019 to February 2020). NE monsoon period was selected to minimize the climatic effects during sampling in different seasons. Macroalgae species were taxonomically identified using the recommended pictorial guides and literature records. Oneway Analysis of Variance (ANOVA) was employed to identify the variations of macroalgae diversity with sampling location (p<0.05). According to the results, a total of 26 macroalgae species (10 belong to Chlorophyta: >38% richness, 10 in Rhodophyta: >38% richness, and 6 from Phaeophyta: >23 % richness) were identified in this coastal belt. Ecologically dominant species belong to division Chlorophyta out of all the sampling sites. Shannon-Wiener biodiversity index (H') of the macroalgae in respective ecosystems significantly changed with sampling locations (p<0.05). The spatial variation pattern of biodiversity is correlated with unsustainable anthropogenic activities and natural factors. Shannon-Wiener biodiversity index (H') ranged at 0.67-2.59 in the study sites. The highest composition of macroalgal species (20) was recorded from the Godawaya site due to the minimum anthropogenic effect. Mirissa (02) and Dodanduwa (01) regions had the lowest macroalgae species richness and commercial activities were relatively higher along these coastal zones compared to all other sites. Accordingly, macroalgae act as the biological indicators reflecting the health status of respective ecosystems. So, the findings of this study would be important to identify the quality of the coastal zones and apply appropriate coastal conservation and management measures in the future. Also, the commonly recorded macroalgae species which belong to Chlorophyta and Rhodophyta can be sustainably utilized in processing value-added foods and other products. In conclusion, this study reveals the current status of macroalgae diversity on the southern coast during the NE monsoon period and detailed investigation of species composition is strongly recommended throughout the year. Keywords: Biodiversity assessment, North east monsoon, Macroalgae, Intertidal zone, Coastal ecosystems
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    Development of a Feed Incorporating Fish Roe Oil for Ornamental Fish
    (Uva Wellassa University of Sri Lanka, 2014) Shanuke, D.S.
    Fish oil contains essential polyunsaturated long chain fatty acids which are crucial for normal growth and survival of the fish. Food fish roe and fish waste contain oils in different levels. Even though roe of food fish have a lower demand in Sri Lanka, there is a potential of extracting edible fish roe oil and fatty acids. In this study, five different oil producing methods; heat and salt extraction, enzymatic hydrolysis, mechanical pressing and solvent extraction were tested with selected four fish species (Thunnus albacares, Katsuwonus pelamis, Canthidermis maculata and Lepidocybium flavobrunneum) to identify the best method, fish roe type and best solvent for roe oil extracting w well as incorporating roe oil in ornamental feed development to enhance growth performances and colouration of Xiphophorus maculatus fish. Solvent extraction with 2-propanol was found to be the best method of producing roe oil considering oil yields. (1.48+0.70 g: T albacares, 1.33+0.10 g: K. pelamis, 1.27+0.25 g: C. maculata and 1.01+0.01 g: F. flavobrunneum). Hence, solvent extraction method was carried out for the selected mature roe of four species using four types of solvents: (50m1) 2-propanol, hexane, acetone and mixture of hexane and 2-propanol (70:30). Oil yields of roe in different maturation stages were (using 2-propanol) measured and compared. Highest 9i1 yields were recorded by mature roe of every species. The results showed a significant difference between oil yields and solvents used for extraction (P<0.05). Highest oil yield was obtained (25 g of matured roe) as 1.60+0.26 g with .acetone extraction for T albacares. It was revealed that roe of T albacares is the most suitable for extraction of roe oil. There is a significant difference between growth performances of Xiphophorus maculatus and feed types. Highest specific growth rate of Xiphophorus maculatus was obtained by Yellow-fin tuna roe oil incorporated feed (2.25 ± 1.2). Keywords: Roe oil, Solvent extraction, Maturation, Specific growth rate
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    Development of Omega-3 Fish Oil Fortified Functional Stirred Yoghurt by Incorporating Annona muricata (Soursop)
    (Uva Wellassa University of Sri Lanka, 2021) Shanuke, D.S.; Marapana, R.A.U.J.; Hettiarachchi, S.; Edirisinghe, E.M.R.K.B.
    Fish oil is an ideal source of Omega-3 polyunsaturated fatty acids (PUFAs) which lower the risk of numerous non communicable diseases. Consumption of fish oil is not popular in Sri Lankan community. This study aimed to develop a fish oil fortified functional stirred fruit yoghurt to deliver Omega-3 PUFAs and to evaluate the effect of fortifying yoghurt with fish oil on sensory, physicochemical properties and oxidative qualities. Initial sensory analysis for fish oil fortified yoghurt was performed by adding 5% (w/w) three different fruit juices including soursop, mango and pineapple by thirty untrained panelists. Fish oil fortified soursop added stirred yoghurt showed the highest score for overall acceptability as 7.32 ± 0.85 (p < 0.05). Results of second sensory analysis have shown that addition of soursop up to 15% (w/w) level was considerably masked the fishy odor and flavor of fish oil (1% w/w) fortified yoghurt. Fish oil emulsion was prepared with guar gum, gelatin and glycerol using Nano emulsion technique. Physicochemical and oxidative qualities were compared among fish oil emulsion added soursop yoghurt (FOESY), fish oil fortified plain yoghurt (FOPY) and bulk fish oil fortified soursop yoghurt (BFOSY) during the storage of 21 days at 4°C. Peroxide values (PV) were analyzed to determine oxidative stability. Syneresis values increased in all yoghurt samples during storage. The highest syneresis value of 45.18 ± 1.98 was recorded by FOPY on day 14. BFOSY and FOESY showed significantly lower syneresis (p < 0.05). pH values gradually decreased and titrable acidity values as lactic acid increased in all treatments during storage.The pH values of both FOESY and BFOSY was 4.5± 0.01 at day 14. FOESY recorded the lowest (p < 0.05) PV (4.64 ± 0.12 mEq O2 kg-1) at day 21 compared to BFOSY and FOPY. The Escherichia coli and coliform counts were complied with the requirements of SLS but yeast and molds counts had exceeded SLS limits after 14 days. This study demonstrated the potential of producing fish oil emulsion fortified functional yoghurt with acceptable level of sensory characteristics, physicochemical properties and oxidative stability by incorporating soursop juice. Keywords: Omega-3; Fortification; Fish oil; Yoghurt; Soursop
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    A Preliminary Study on Potentials of Seaweed Culture as an Alternative Livelihood for Small Scale Fishing Community in Southern Coast of Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2020) Gayathry, L.D.; Silva, A.P.R.; Shanuke, D.S.; Wijethunge, H.N.S.; Egodauyana, K.P.U.T.; Dharmakeerthi, T.N.; Jayarathna, W.N.D.S.; Bambaranda, B.V.A.S.M.
    Large scale seaweed mariculture is widespread in many Asian countries for decades. But Sri Lanka is still in its infancy. Therefore, promoting seaweed mariculture as a commercialscale industry is an urged necessity. Seaweeds grow abundantly along the southern coast of Sri Lanka. Therefore, the study attempted to assess the socio-economic status of small-scale fishermen, the potentiality of using seaweed culture as an alternative livelihood, and awareness of fishermen regarding seaweed culture on the southern coast of Sri Lanka. Data were collected by key-informant interviews and questionnaire surveys from November 2019 to February 2020. Cluster sampling was used to draw a sample of 160 fishermen from 8 major landing sites. Results of the socio-economic analysis showed that 72% of fishermen were between the age group of 35 - 55 years. Due to the seasonality of fishing, 65% of fishermen are having below-average monthly income (LKR 12,000 - 15,000). In three landing sites, 25% of fishermen are seasonal fishers. But almost all fishers are active in other landing sites. In total, 90% of fishermen are interested in seaweed farming. Identified reasons for their interest in seaweed culture were, additional income (85%), manageable with fishing (65%), and women empowerment (58%). Results relevant to awareness on seaweed farming among fishermen 80 - 90% in four landing sites, 60 - 65% in two landing sites, and below 30% in the other two landing sites. Favorable environmental conditions, adequate workforce, and willingness to initiate seaweed culture were identified as potentials. Absence of proper mechanism to disseminate knowledge, financial support, and lack of knowledge on marketing were identified as constraints for the initiation of seaweed farming. Accordingly, knowledge regarding seaweed farming should be disseminated and effectively transferred. The overall results indicate greater potential to initiate seaweed mariculture as an alternative livelihood for small scale fishing communities in southern Sri Lanka. Keywords: Seaweed, Mariculture, Fishing community, Alternative livelihood, Southern coast
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    A Study on the Potential of Extraction of Roe Oil from Thunnus albacares, Katsuwonus pelamis, Canthidermis maculata and Lepidocybium flavobrunneum
    (Uva Wellassa University of Sri Lanka, 2019-02) Shanuke, D.S.; Coswatte, A.C.W.W.M.C.L.K.; Jayamanne, S.C.
    Fish oil contains essential polyunsaturated long chain fatty acids which are crucial for normal growth and survival of the fish. Food fish roe and fish waste contain oils in different levels. Even though roe of food fish has a lower demand in Sri Lanka, there is a potential of extracting edible fish roe oil and fatty acids. In this study, five different oil producing methods; heat and salt extraction, enzymatic hydrolysis, mechanical pressing and solvent extraction were tested with selected four fish species (Thunnus albacares, Katsuwonus pelamis, Canthidermis maculata and Lepidocybium flavobrunneum) to identify the best method and best fish roe type for edible roe oil production. Solvent extraction with 2-propanol was found to be the best method of producing roe oil considering oil yields (1.48±0.70 g: T. albacares, 1.33±0.10 g: K. pelamis, 1.27±0.25 g: C. maculata and 1.01±0.01 g: F. flavobrunneum). Hence, solvent extraction method was carried out for the selected matured roe of four species using four types of solvents: (50ml) 2-propanol, hexane, acetone and mixture of hexane and 2-propanol (70:30). Oil yields of roe in different maturation stages were (using 2-propanol) measured and compared. Highest oil yields were recorded by matured roe of (K. pelamis: 1.18±0.14 g, T. albacares: 1.03±0.32 g, L. flavobrunneum: 1.01±0.01 g and C. maculata: 0.94±0.52 g). Oil yields of immature roe in all four fish species were negligible. The results showed a significant difference between oil yields and solvents used for extraction (P<0.05). Highest oil yield was obtained (25 g of matured roe) as 1.60±0.26 g with acetone extraction for T. albacares followed by 2-propanol: hexane mixture, 2-propanol and hexane solvents were recorded oil yields of 1.43±0.89 g & 1.18±0.14 g for K. pelamis and 0.64±0.17 g for T. albacares respectively. It was revealed that roe of T. albacares is the most suitable for extraction of roe oil.