Zoology
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Item Haemato-immunological and histological responses in Nile tilapia, Oreochromis niloticus exposed to titanium dioxide nanoparticles.(Sri Lanka Journal of Aquatic Sciences, 2012) Perera, S.; Pathiratne, A.Increased industrial application of nanotechnology has potential to increase nanoparticle contaminations in aquatic ecosystems. However a large knowledge gap exists on influence of nanoparticles on fish populations inhabiting receiving waters. The present study reports the effects of exposure to aquatic suspensions of titanium dioxide nanoparticles (TiO2 NPs, anatase, particle size <25nm: 0, 1, 10 mg l-1, for 7 and 14 days) on some haematological/ innate immune responses and histological structure of gills, liver and intestine of Nile tilapia, an economically important freshwater fish in tropical regions. The results show that TiO2 NPs exposure conditions were not lethal to Nile tilapia but lead to blood parameter alterations and histopathological changes in the organs. Upon exposure of fish to both concentrations of TiO2 NPs for 14 days, erythrocyte counts, haemoglobin levels, total leucocyte counts and percent neutrophils in the peripheral blood were increased significantly (P <0.05) in comparison to the control fish. Despite increases in neutrophils, total phagocytic and myeloperoxidase activities of the blood of fish exposed to 10 mg L-1 TiO2 NPs were depressed significantly (P <0.05) whereas respiratory burst activity was not altered. Serum lysozyme activities in the fish exposed to 10 mg l-1 TiO2 NPs were elevated significantly (P <0.05) compared to the controls. Histological changes seen in the tilapia exposed to TiO2 NPs were epithelial separation, mucous cell proliferation, hyperplasia and lamellae fusion in the gills; hepatocytes with vacuolations, pycnotic nuclei, apoptosis and necrosis in the liver; eroded villi epithelium, reduction of mucous cells and degeneration of mucosa of the intestine. Although blood parameter alterations seen in Nile tilapia can be considered as physiological responses of the fish to cope up with the TiO2 NPs induced stress, observed organ pathologies could lead to serious health implications. Hence, detail studies with a range of environmentally relevant levels are warranted to investigate chronic effects of TiO2 nanoparticles on health of fish populations in the receiving water bodies. We recommend use of Nile tilapia as a tropical fish model for further studies on nanotoxicity.Item Multiple biomarker responses of Nile tilapia (Oreochromis niloticus) exposed to textile industry effluents reaching Bolgoda North Lake, Sri Lanka(Sri Lanka Journal of Aquatic Sciences, 2013) Perera, B.I.G.; Pathiratne, A.Textile industry effluents contain a complex mixture of chemicals which may have potential threats to biota. The present study was carried out to assess the potential impacts of selected textile industry effluents entering Bolgoda North Lake, Sri Lanka using multiple biomarkers responses of Nile tilapia viz. brain acetylcholinesterase (AChE), hepatic ethoxyresorufin O-deethylase (EROD) and erythrocytic micronuclei/nuclear alterations. The biomarker responses were determined in the fish upon exposure to the undiluted and diluted effluents along with the respective controls. Brain AChE activities of the fish exposed to the textile industry effluents were depressed (up to 40%) and frequencies of erythrocytic micronuclei and nuclear alterations were increased (up to 9 folds) significantly indicating the availability of neurotoxic and genotoxic substances in the effluents. Strong induction of hepatic EROD activities (up to 23 folds) in the exposed fish revealed the availability of CYP1A inducing pollutants which may have contributed to enhance the genotoxic potential of the effluents. The results revealed the sensitivity of these biomarkers of Nile tilapia to assess the biological effects of textile industry effluents. The depression of AChE activities and induction of EROD levels along with enhanced micronuclei and nuclear alterations in the fish exposed to the selected effluents can be considered as early warning signs for possible impacts pose by the textile industry effluents on fish populations inhabiting the effluent receiving water bodies.Item Modulation of ethoxyresorufin O-deethylase and glutathione S-transferase activities in Nile tilapia (Oreochromisniloticus) by polycyclic aromatic hydrocarbons containing two to four rings: implications in biomonitoring aquatic pollution(Ecotoxicology, 2010) Pathiratne, A.; Hemachandra, C.K.Despite ubiquity of polycyclic aromatic hydrocarbons (PAHs) in the tropical environments, little information is available concerning responses of tropical fish to PAHs and associated toxicity. In the present study, effects of five PAHs containing two to four aromatic rings on hepatic CYP1A dependent ethoxyresorufin O-deethylase (EROD), glutathione S-transferase (GST) and serum sorbitol dehydrogenase (SDH) activities in Nile tilapia, a potential fish species for biomonitoring pollution in tropical waters, were evaluated. Results showed that EROD activities were induced by the PAHs containing four aromatic rings (pyrene and chrysene) in a dose dependent manner. However PAHs with two to three aromatic rings (naphthalene, phenanthrene and fluoranthene) caused no effect or inhibition of EROD activities depending on the dose and the duration. Fluoranthene was the most potent inhibitor. SDH results demonstrated that high doses of fluoranthene induced hepatic damage. GST activity was induced by the lowest dose of phenanthrene, fluoranthene and chrysene but high doses had no effect. The results indicate that induction of EROD enzyme in Nile tilapia is a useful biomarker of exposure to PAHs such as pyrene and chrysene. However EROD inhibiting PAHs such as fluoranthene in the natural environment may modulate the EROD inducing potential of other PAHs thereby influencing PAH exposure assessments.Item Species composition and abundance of littoral oligochaete fauna in Lunuwila reservoir, Sri Lanka(International Review of Hydrobiology, 2000) Weerasundara, A.; Pathiratne, A.; Costa, H.H.Item Morphological and histological changes in the gonads of the estuarine cichlid fish Etroplussuratensis (Bloch) during gonadal development(Bulletin of the National Institute of Oceanography, 1984) Pathiratne, A.; Costa, H.H.