Browsing by Author "Hettiarachchi, M."

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Antibacterial activity of aqueous Neem leaf (Azadirachta indica A. Juss) extract on a pathogenic Aeromonas sp. and immunostimulating property of the extract on Koi carp, Cyprinus carpio Linnaeus
(Institute of Biology, Sri Lanka, 2013) Wickramasinghe, T.K.C.; Hettiarachchi, M.
A comparative study on the quality of postlarvae of black tiger shrimp, Penaeus monodon, produced in some Sri Lankan shrimp hatcheries with different Management systems
(Sri Lanka Association for Fisheries and Aquatic Resources, 2004) Hettiarachchi, M.; Hettiarachchi, C.
Stocking of high quality post larvae in grow-out systems is regarded as one of the key factors that influence the quality of shrimp at harvest. Therefore, it is important to investigate whether there are differences in the quality of post larvae produced in hatcheries with different management systems. A survey was carried out and shrimp hatcheries situated in the North Western Province, Sri Lanka were categorized into 3 major types as hatcheries with a high level of management, medium level of management and low level of management, considering the facilities available and production procedures adopted in them. A less expensive scoring system was developed to assess the quality of post larvae using external appearance to the naked eye, behavioural patterns, length variation, appearance under the microscope, gut to muscle ratio, gut fullness, survival under stress tests and occurrence of certain disease symptoms. Nine shrimp hatcheries, three from each level of management were then selected, five random samples each containing more than three hundred post larvae (Pl15 – Pl18) were obtained from each hatchery and the quality of post larvae was assessed using the scoring system developed. When mean total scores received from the scoring system were compared, it was found out that the quality of post larvae produced in the hatcheries with high and medium levels of management was significantly higher than that of post larvae produced in the hatcheries with low level of management (P<0.05) while there was no significant difference between the quality of post larvae produced in the hatcheries with high and medium levels of management (P>0.05).
Critical better management practices and critical bio-security measures for prevention of entry and spread of white spot virus and pathogenic Vibrio in grow-out farms of cultured Penaeus monodon in Sri Lanka
(Sri Lanka Journal of Aquatic Sciences, 2018) Kumara, K.R.P.S.; Hettiarachchi, M.
Since the first record of white spot disease (WSD) in 1996, PCR tested, white spot virus (WSV) free post larvae of Penaeus monodon (Fabricius 1798) are stocked in grow-out farms as the major bio-security measure. However, significantly high mortality in young shrimp and total rejection of harvest have been recorded in North Western Province, Sri Lanka due to WSD and/or vibriosis. Present study was planned to identify critical better management practices (CBMPs) and critical bio-security measures (CBSMs) that should be strictly adopted to prevent the entry and spread of WSV and pathogenic Vibrio in grow-out farms of P. monodon. A questionnaire survey, carried out at randomly selected 100 grow-out farms located in the North Western Province, revealed that there was a relationship between the occurrence of WSD and /or vibriosis and levels of practicing better management practices (BMPs) and/or bio-security measures (BSMs). Proper pre-stocking pond preparation, adoption of zero water exchange, monitoring and controlling water quality parameters including pathogenic Vibrio in culture water and use of a suitable bioaugmenter and a probiotic were identified as the CBMPs while proper disinfection of culture water, stocking of WSV and MBV free post larvae and prevention of WSV contamination through other routes over the rearing period were the identified CBSMs. Entry and spread of WSV and pathogenic Vibrio in P. monodon grow-out farms in the North Western Province, Sri Lanka could be prevented by strict adoption of CBMPs and CBSMs identified during the present study.
Development of a shrimp grow out feed with locally available ingredients and evaluation of production performance of the shrimp, Peaneus monodon under the developed feed
(Sri Lanka Association for Fisheries and Aquatic Resources, 2002) Dissanayake, C.D.A.M.P.A.; Hettiarachchi, M.
Different isolates of Bacillus subtilis from gastrointestinal tract of wild caught black tiger shrimp, Penaeus monodon to improve a locally produced probiotic/bioaugmenter for controlling pathogenic Vibrio in Sri Lankan shrimp culture systems
(Faculty of Graduate Studies, University of Kelaniya, 2015) Hettiarachchi, D.C.; Kumara, K.R.P.S.; Hettiarachchi, M.
Bacillus species are the major probiotic bacteria used in both hatchery and grow-out systems of tropical shrimp culture industry to control pathogenic Vibrio species. Our previous works have confirmed that the use of a locally produced probiotic/bioaugmenter containing a locally isolated strain of Bacillus subtilis could contribute significantly in producing healthy post larvae of Penaeus monodon and in obtaining a profitable harvest from grow-out ponds compared to systems that did not use the product. Therefore, present study was planned to isolate different isolates of Bacillus subtilis to improve that probiotic or to formulate a new probiotic with improved performances. Samples of apparently healthy black tiger shrimp, P. monodon residing in estuaries in the North Western Province were transported to the laboratory. Gastrointestinal tract samples of the shrimp were first subjected to heat treatment (to kill non-spore forming bacteria) and isolation, purification and characterization of different isolates of Bacillus subtilis were carried out following standard microbiological procedures. Isolates were identified as different strains of Bacillus subtilis by biochemical tests in API 20E and API 50 CHB test kits (bioMerieux, France). Out of the nine different isolates of B. subtilis, only three displayed high growth rate while tolerating wide range of salinity (5gL-1 to 35gL-1) and pH (6 to 10). Antagonistic properties of those three isolates of B. subtilis on five species of pathogenic Vibrio of cultured shrimp in Sri Lanka (isolated and identified in our previous work) were investigated. The diameter of inhibitory zones produced by the new isolates of B. subtilis on the pathogenic Vibrio species ranged from 2 to 4 mm; they could be used to improve the locally produced probiotic/bioaugmentor. The selected three isolates of B. subtilis have been sent for the confirmation of strain type by DNA analysis.
Effect of a commercially available probiotic on growth and survival of an ornamental fish, Guppy, Poecilia reticulata
(Sri Lanka Association for Fisheries and Aquatic Resources, 2005) Chandrasiri, M.A.C.D.; Hettiarachchi, M.
Effect of a commercially available probiotic on survival, growth and quality of hatchery produced Penaeus monodon post larvae
(Sri Lanka Association for Fisheries and Aquatic Resources, 2009) Ramachandra, R.C.M.S.; Hettiarachchi, M.
Effect of Better Management Practices (BMPs) on shrimp production and occurrence of outbreaks of white spot syndrome in tiger shrimp, Penaeus monodon, in grow out ponds
(Sri Lanka Association for Fisheries and Aquatic Resources, 2009) Wijitha, G.; Hettiarachchi, M.
Effect of dietary fishmeal replacement in the formulated food by heat processed soybean meal in growth, survival and crude protein level of fingerlings of Genetically Improved Farm Tilapia (GIFT)
(Sri Lanka Association for Fisheries and Aquatic Resources, 2006) Yatawara, M.D.M.D.W.M.M.K.; Hettiarachchi, M.
Effect of light on mortality and growth of embryos, larvae and fry of catfishes, Clarias glariepinus Burchell, 1822 Clarias anguillaris Linnaeus, 1762
(Sri Lanka Association for the Advancement of Science, 1991) Hettiarachchi, M.
Effect of raw garlic extract on common external parasites, Ichthyophthirius multifiliis, Gyrodactylus spp. and Dactylogyrus spp. on goldfish, Carassius auratus
(Sri Lanka Association for Fisheries and Aquatic Resources, 2012) Jayasundara, J.M.C.N.; Hettiarachchi, M.
Ichthyophthirius multifiliis (a ciliate), Gyrodactylus spp. and Dactylogyrus spp. are common, external, harmful parasites of goldfish, Carassius auratus. Bath treatments with different chemicals that could be harmful to the environment as well as to the fish are used by Sri Lankan farmers to control these parasites. The present study was planned to investigate the efficacy of row garlic (Allium sativum) extract in controlling I. multifiliis, Gyrodactylus spp. and Dactylogyrus spp. on goldfish. In vitro test was carried out with different concentrations of row garlic extract to find out the effective minimum concentration required to kill I. multifiliis; toxicity of the extract on healthy goldfish was tested at a range of concentrations closer to this effective minimum concentration. In vivo test was performed at different concentrations of garlic extract and random samples of fish were observed for the presence of parasites two times a day. Anti-parasitic efficacy of the plant extract on I. multifiliis and both flukes were calculated. The effective minimum concentration of row garlic extract to kill I. multi(iliis in vitro experiment was 2S0 mgr' at exposure time of 3.5 hours. In vivo experiment revealed that garlic extract at concentration of 260 mgr' and 270 mgr' could kill/ remove aliI. multifiliis and both monogenean flukes respectively from the body and gills of goldfish in 3 days of exposure at 24°C-27°C; antiparasitic efficacy (1.S7l:t0.00) recorded for garlic extract at the respective concentrations on I. multifiliis and monogenean flukes were not significantly different (P>O.OS) from the antiparasitic efficacy recorded for formalin at 200 mgr' at 4 hours of exposure time, which was the positive control. Histopathology revealed that the effect of formalin treatment on gill tissues of treated fish was greater compared to the effect of treatment with garlic extract.
Effect of vitamin C and β,1-3,1-6 glucan on the growth of ornamental fish swordtail, Xiphophotus helleri
(Institute of Biology, Sri Lanka, 2009) Yasapala, S.N.; Hettiarachchi, M.
Effects of shrimp farming practices on water quality of northern part of the Dutch canal
(Sri Lanka Association for Fisheries and Aquatic Resources, 2010) Gunawardana, P.V.S.L.; Epa, U.P.K.; Hettiarachchi, M.
Most of the shrimp farms in Sri Lanka are concentrated over a distance of about 120 km around Chllaw Lagoon, Dutch Canal, Mundal Lake and Puttalam Lagoon, with 70% of farms depending on the Dutch Canal for water. Farms take water in from the canal and discharge their effluent into the same water sources without proper treatments. Discharge of pond effluent has led to deterioration of water quality in the main water sources. Present study was carried out to investigate the changes of water quality parameters in Northem part of Dutch canal (7"63'N 79 _D80'E to 7 D85'N 79 D80'E) in relation to different shrimp farming practices in selected five sampling sites at Karukkupane, Nalladarankattuwa, Muthupanthiya, Udappuwa and Madurankuliya_ Water samples were collected biweekly from September 2008 to January 2010 from both surface and bottom layers at the pre-selected sampling points. Temperature, turbidity, conductivity, saliliity, BOO, DO, TDS, flow rate, pH, NH3, PO."' and chlorophyll- a in the collected water samples were analyzed. In addition, shrimp farming activities adjacent to five sampling points were recorded. Surface water samples did not show significant inter-site differences for the parameters determined except for temperature, DO and pH which are subjected to diumal variations too. Bottom water samples of Udappuwa and Madurankuliya had significantly higher levels (P< 0.05) of turbidity (24.25 :I: 8.4 NTU and 32.4 :I: 9.3 NTUj. pH (9.1:1: 2.3 and 10.2:1: 1.6), NH3(0.22:1: 0.006 mgll and 0.32:1: 0.012 mgll PO. (0.046 :1:0.007 mgll and 0.079 :I: 0.011 mgll) , chlorophyll-a (27.2 :I: 8.3 mg m and 32.8 :I: 6.1 mg m-3) and BOO (2.42 :I: 0.60 mgJI and 3.40 :I: 0.8mg1l) compared to other sampling sites. Flow rates of water at five sampling points didn't show significant differences ( P>0.05) and had an average value of 1.3 :I: 0.36 m3/s. Sub optimal levels for DO, BOO, pH, NH3, PO."' and chlorophyll-a were recorded at Udappuwa, Madurankuliya and Muthupanthiya areas of the Dutch canal, where shrimp farm density is moderately higher. Results of the study exemplify that higher levels of shrimp farming activities can alter quality of water in the Dutch Canal, making it less suitable for shrimp culture. Therefore it is suggested to have treatment facilities especially at the areas like Udappuwa, Madurankuliya and Muthupanthiya, to improve the quality of receiving water from shrimp farms in order to minimize the environmental impacts of shrimp culture industry and to assure the sustain ability of future shrimp cultivation.
Efficacy of Human Chorionic Gonadotropin (HCG) and crude pituitary extract of fish and frog in oocyte maturation and ovulation in African catfishes, Clarias glariepinus Burchell, 1822 Clarias anguillaris Linnaeus, 1762
(Sri Lanka Association for the Advancement of Science, 1991) Hettiarachchi, M.
The Efficacy of micronutrient supplementation in reducing the prevalence of anaemia and deficiencies of zinc and iron among adolescents in Sri Lanka
(Nature Publishing Group, 2008) Hettiarachchi, M.; Liyanage, C.; Wickremasinghe, R.; Hilmers, D.C.; Abrams, S.A.
Efficacy of natural wetlands in treating shrimp pond effluents in North western province of Sri Lanka
(Sri Lanka Association for Fisheries and Aquatic Resources, 2009) Gunawardena, P.V.S.L.; Epa, U.P.K.; Hettiarachchi, M.
Efficacy of Quinaldine Sulphate as an anesthetic for the ornamental carp (Cyprinus carpio) in simulated packaging for long distance transport
(Sri Lanka Association for Fisheries and Aquatic Resources, 1999) Hettiarachchi, M.; Senadheera, S.P.S.D.
Enhancement of immunity in cultured shrimp, Penaeus monodon induced by Achyranthes aspera (Sin. Karal heba, Family: Amaranthaceae) compared to a commercial immune enhancer
(Institute of Biology, Sri Lanka, 2015) Karawita, K.V.D.H.R.; Hettiarachchi, M.
Experimental transmission of white spot disease virus (SEMBV) to tiger shrimp (Penaeus monodon) under different salinity and hardness levels in water
(University of Kelaniya, 2000) Somathilake, R.P.H.; Hettiarachchi, M.; Pathiratne, A.
Growth performance and color enhancement of guppy, Poecilia reticulata when fed with locally formulated pigment included diets
(Sri Lanka Association for Fisheries and Aquatic Resources, 2000) Hettiarachchi, M.; Dassanayake, R.M.P.S.