Zoology

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Author: search.filters.author.Hemachandra, C.K.Has files: Yes

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    Heavy metal levels in water and sediments of Bathalagoda Reservoir, Sri Lanka
    (Sri Lanka Association for Fisheries and Aquatic Resources, 2010) Hemachandra, C.K.; Pathiratne, A.; Pathiratne, K.A.S.
    Bathalagoda reservoir, a fresh water body located in the Kurunegala District of Sri Lanka is used by the residents in the area for irrigating paddy fields, drinking and bathing purposes and for culture-based fisheries. The present study was carried out to determine the selected heavy metal levels viz. lead, cadmium and copper in water and sediments of the reservoir to assess the extent of heavy metal pollution. Water and sediment samples were obtained from three locations of the reservoir namely Ibbagamuwa, Moragolla and Madihe- Mudunduwa during the period September 2007 - July 2009 and the heavy metal levels were determined by Atomic Absorption Spectrometry following standard procedures. The results showed that lead, cadmium and copper levels in water ranged from not detectable level to 2 g L", not detectable level to 3 g L" and not detectable level to 3 g L" respectively. Corresponding metal levels in the sediments (dry weight basis) ranged from not detectable level to 523 g g", not detectable level to 0.1 g g" and not detectable level to 26 g g" respectively. Significant site specific variations or seasonal variations were not observed in relation to the heavy metal levels in water and sediments of the reservoir. The results revealed that the levels of lead, cadmium and copper in the reservoir water are far below the maximum permissible levels specified by the international regulatory authorities (World Health Organization and United States Environmental Protection Agency) for drinking water and water used for irrigation purposes.
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    Histopathology of gills and liver tissues of Nile tilapia inhabiting Bolgoda North Lake, Sri Lanka
    (Sri Lanka Association for Fisheries and Aquatic Resources, 2010) Hemachandra, C.K.; Pathiratne, A.
    Bolgoda North Lake. an urban water body located in the Western Province of Sri Lanka is becoming polluted with anthropogenic chemicals including heavy metals and toxic organic pollutants such as polycyclic aromatic hydrocarbons. Histopathological lesions can be used as indicators for the effects of various anthropogenic pollutants on fish and are a reffection of the overall health of the entire fish population in the aquatic ecosystem. The present study was carried out to investigate the histological structure of gill and liver tissues of Nile tilapia (Oreochromis nifoticus), a food fish inhabiting 60lgoda North Lake to evaluate the general health status of the fish population. The tissue samples were taken from the fish inhabiting the Lake during September 2007 to July 2009 and histological sections of the gill and liver tissues were prepared according to the standard methodologies. In addition serum sorbitol dehydrogenase (SDH) enzyme activities in the fish were determined to evaluate the chemically induced liver damage. Several histological alterations in gill tissues viz. hyperplasia in primary and secondary lamellae, fusion of primary and secondary lamellae, mucous cell proliferation, necrosis in lamellar epithelial cells, lamellar hypertrophy, clubbing at the tips of secondary lamellae, and telangiectasis were observed in most of the fish examined. Epithelial hyperplasia in secondary lamellae and mucous cell proliferation were the most abundant types of lesions in the gill tissues of sampled fish. In addition metacercarian parasitic cysts in the gill tissue were observed in some of the fish examined. The liver tissues of the fish showed prominent histological alterations including swelling of hepatocytes, pyknosis of hepatocytes nuclei, breakdown of liver cell walls, cytoplasmic vacuolation, focal and zonal necrosis, fibrosis in the hepatic tissue, melano macrophage aggregates, vacuoles in the pancreatic tissue and bile duels, pancreatic cell necrosis, and sinusoidal congestion in the blood vessels & central veins. Cytoplasmic vacuolation, focal cell necrosis and melano macrophage aggregates were the most common types of liver lesions observed in the fish. Histopathological alterations in gill and liver tissues of Nile tilapia indicate that the fish population residing in 60lgoda North Lake is under threat due to chemical contamination. Elevated serum SDH enzyme activities in the blood of the examined fish confirmed chemically induced liver damage.
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    Screening toxicity of selected industrial effluents reaching Kelani River, Sri Lanka using Allium cepa (Common onion) bioassay
    (Sri Lanka Association for the Advancement of Science, 2013) Hemachandra, C.K.; Pathiratne, A.
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    Biomonitoring of genotoxic contamination in two selected water bodies using erythrocytic nuclear abnormalities in feral Nile tilapia
    (Sri Lanka Association for Fisheries and Aquatic Resources, 2009) Hemachandra, C.K.; Pathiratne, A.
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    Monitoring contaminations of Aryl hydrocarbon Receptor (AhR) agonists in two selected water bodies in Sri Lanka
    (Sri Lanka Association for Fisheries and Aquatic Resources, 2008) Hemachandra, C.K.; Pathiratne, A.; Pathiratne, K.A.S.
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    Biliary fluorescence aromatic compounds in Nile tilapia (Oreochromis niloticus) as biomarkers of exposure to polycyclic aromatic hydrocarbons
    (Sri Lanka Association for Fisheries and Aquatic Resources, 2007) Pathiratne, A.; Hemachandra, C.K.; Pathiratne, K.A.S.
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    Analysis of bile fluorescence profiles of feral Nile tilapia as biomarkers of exposure to polycyclic aromatic hydrocarbons: associations with the rainfall
    (Sri Lanka Journal of Aquatic Sciences, 2011) Hemachandra, C.K.; Pathiratne, A.
    The present study was conducted to evaluate the potential use of bile fluorescence patterns of feral Nile tilapia (Oreochromis niloticus) as biomarkers of exposure to polycyclic aromatic hydrocarbon (PAH) contaminations in tropical waters. Bile fluorescence profiles of the fish inhabiting two water bodies with different levels of PAH pollution (Weras Ganga and Bathalagoda reservoir) were investigated at regular intervals over two years (September 2007 to July 2009) using fixed wavelength fluorescence and synchronous fluorescence spectrometry. Despite temporal variability of the bile fluorescence patterns, the fluorescence signals corresponding to naphthalene-, phenanthrene-, pyrene- and benzo(a)pyrene- type metabolites were consistently higher in the fish from Weras Ganga compared to the fish from Bathalagoda reservoir and the laboratory maintained control fish indicating that the fish inhabiting Weras Ganga had been continuously exposed to higher levels of PAHs. Summated fluorescence for the four types of PAH metabolites and fluorescence signals corresponding to naphthalene- and pyrene- type metabolites in the fish from Weras Ganga were positively correlated (P < 0.05) with the rainfall pattern indicating more PAH inputs associated with the rainfall. Despite slight temporal variations, no significant associations were found between the biliary fluorescence signals in the fish from Bathalagoda reservoir and the rainfall pattern. This field study supports the use of bile fluorescence patterns in feral Nile tilapia as a simple and rapid method for screening contamination and bioavailability of PAH in tropical freshwater bodies.