Zoology
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Item Comprehensive evaluation of demographic,socio-economic and other associated risk factors affecting the occurrence of dengue incidence among Colombo and Kandy Districts of Sri Lanka: a cross-sectional study(Parasites & Vectors (2018) 11:478, 2018) Udayanga, L.; Gunathilaka, N.; Iqbal, M.C.M.; Lakmal, K.; Amarasinghe, U.S.; Abeyewickreme, W.Background: Comprehensive understanding of risk factors related to socio-economic and demographic status and knowledge, attitudes and practices (KAP) of local communities play a key role in the design and implementation of community-based vector management programmes, along with the identification of gaps in existing control activities. Methods: A total of 10 Medical Officers of Health (MOH) areas recording high dengue incidence over the last five years were selected from Colombo (n = 5) and Kandy (n = 5) Districts, Sri Lanka. From each MOH area, 200 houses reporting past dengue incidence were selected randomly as test group (n = 1000 for each district) based on the dengue case records available at relevant MOH offices. Information on socio-economic and demographic status and knowledge, attitudes and practices were gathered using an interviewer administered questionnaire. The control group contained 200 households from each MOH area that had not reported any dengue case and the same questionnaire was used for the assessment (n = 1000 for each district). Statistical comparisons between the test and control groups were carried out using the Chi-square test of independence, cluster analysis, analysis of similarities (ANOSIM) and multidimensional scaling (MDS) analysis. Results: Significant differences among the test and control groups in terms of basic demographic and socio-economic factors, living standards, knowledge, attitude and practices, were recognized (P < 0.05 at 95% level of confidence). The test group indicated similar risk factors, while the control group also shared more or less similar characteristics as depicted by the findings of cluster analysis and ANOSIM. Findings of the present study highlight the importance of further improvement in community education, motivation and communication gaps, proper coordination and integration of control programmes with relevant entities. Key infrastructural risk factors such as urbanization and waste collection, should be further improved, while vector controlling entities should focus more on the actual conditions represented by the public on knowledge, attitudes and personal protective practices. Conclusions: The design of flexible and community friendly intervention programmes to ensure the efficacy and sustainability of controlling dengue vectors through community based integrated vector management strategies, is recommended.Item Application of pollution indices to quantify the pollution status of shallow sediments of the Bolgoda Lake, Sri Lanka(National Science Foundation of Sri Lanka, 2016) Wijeyaratne, W.M.D.N.The present study was conducted to assess the pollution status of the shallow sediments of the Bolgoda Lake in Sri Lanka using sediment pollution indices. Shallow sediment samples were collected as replicates from five sites with different land uses in the monsoonal and nonmonsoonal seasons in 2013. The samples were acid digested and analysed for Cd, Cr, Cu, Ni, Fe and Zn. The heavy metal concentrations were used to calculate: (1) contamination factor (Ci f ); (2) degree of contamination (Cd); (3) pollution loading index (PLI); (4) enrichment ratio (ER); (5) geoaccumulation index (Igeo) and (6) ecological risk factor (Eri ) of the shallow sediment samples. In addition, the quality of the sediments were also assessed by comparing with the numerical sediment quality guidelines (SQGs) and consensus-based sediment quality guidelines (CBSQGs). Significant spatial variations of element concentrations and sediment quality indices were identified in the study area. The pollution level of the study sites ranged from unpolluted to heavily polluted due to heavy metals. The contamination factors for all the heavy metals except Zn indicated moderate, considerable or very high level of pollution in both sampling sessions. The potential ecological risk factor for the heavy metals ranked as Cd > Ni > Cr > Cu > Zn for both sampling sessions indicating the highest potential ecological risk from Cd. The pollution load index for all the study sites except site E in both sampling sessions showed human associated pollution with a PLI higher than 1. All the samples were categorised into class 1 (unpolluted to moderately polluted status) with respect to Cr, Ni, Cu and Zn and to class 0 (unpolluted status) with respect to Cd. The concentrations of Zn and Cd in the present study were lower than the threshold effect concentration (TEC) level of CBSQGs and therefore, was indicated as unlikely to be causing toxicity to benthic organisms. The concentrations of Cr and Ni were higher than the probable effect concentration (PEC) level of CBSQGs and indicated a probable toxicity to benthic organisms.Item Indigenous knowledge in the beach seine fisheries in Sri Lanka: An indispensable factor in community-based fisheries management(Journal of Marine Policy, 2015) Deepananda, K.H.M.A.; Amarasinghe, U.S.; Jayasinghe-Mudalige, U.K.Small-scale fishing over the globe is based primarily on fisher indigenous knowledge (IK), accumulated through many generations of close interactions between people and the natural world. Community-based beach seine fisher communities of southern Sri Lanka were studied through standard ethnographic methods to ascertain the traditional method in using fishers’ IK, and explore empirically the accuracy in using those methods distilled from the traditional fishers. Study revealed that, inter alia, traditional fishers use IK to predict the commencement of fishing season, and identify and quantify the species composition occurring at their fishing territory. Ten traditional methods those which are important for identifying and quantifying the fish school were distilled. Explored methods frequently used by traditional fishers were based on the changes of seawater color (folk oceanography) and the behaviour of sea terns (Sterna sp.). Traditional fishers’ responses on frequency of utility of explored methods in day-to-day fishing activities were in accordance with the findings of the empirical study. Moreover, principal component analysis (PCA) revealed that PC score loading in fishers’ expectation and fishers’ realization had a positive significant relationship (r=0.814, p<0.001). This indicated that traditional fishers’ expectation on composition and quantity of fish school arriving at fishing territory (ex-ante) is accurate and reliable at the realization (ex-post). As such, there exist opportunities to fisheries co-management for the coastal fisheries in Sri Lanka, incorporating fishers’ indigenous knowledge in resource exploitation.Item Coastal water body database to monitor the water quality and land use changes from remote sensing data(Remote Sensing Society of Japan (RSSJ), 2012) Dahanayaka, D.D.G.L.; Tonooka, H.; Wijeyaratne, M.J.S.; Minato, A.; Ozawa, S.Item Feasibility Study for the Estimation of the Chlrophyll-a Using ASTER Data in an Eutrophic Lake, Sri Lanka(Japan Geoscience Union, Japan., 2014) Dahanayaka, D.D.G.L.; Tonooka, H.; Wijeyaratne, M.J.S.; Minato, A.; Ozawa, S.The objective of this study is to evaluate the performance of the previously proposed band ratio approach in estimating Chl-a in Bolgoda Lake, Sri Lanka as a representative example of Case II waters. Lake is located at western province in an area with lot of industries and also with some agricultural activities. Considerable amount of industrial effluents are discharged into it. Illegal filling and also encroachment has occurred in the recent past. This study focused on to determine the trends in eutrophication via Chl-a changes during the recent past, make predictions and recommend mitigatory measures and suggest precautionary measures to restore the environment. From March to December 2013, water samples at 5 points of Lake were collected once per month parallel to ASTER overpass and Chl-a of each sample was measured using a laboratory spectrophotometer. Cloud-free ASTER scenes acquired over Lake under clear sky conditions were selected during 2000 to 2013 for Chl-a estimation and trend analysis. All the ASTER images were atmospherically corrected using FLAASH and in-situ Chl-a data on Lake were regressively analyzed with atmospherically corrected three ASTER VNIR band ratios such as B1/B2 of the same date. Finally, the regression equation of the band ratio with highest correlation (B1/B2; R2 = 0.78) was used to develop algorithm for generation of 15-m resolution Chl-a distribution maps using atmospherically corrected time series satellite imageries in day by day basis. This method applied for ASTER band 1/2 ratio due to Chl-a is positively correlated with the green band reflectance and negatively correlated with the red band reflectance. Therefore, the reflectance ratio of green and red bands becomes a robust parameter to estimate the Chl-a content. According to the ASTER based Chl-a distribution maps it is clearly evident that eutrophication of the Bolgoda Lake has been gradually increased from 2005-2011. Further, results showed that there were significant eutrophic conditions throughout the year 2013 in several parts of the Lake and considerable spatial heterogeneity with higher concentrations being recorded water stagnant areas and in water adjacent to freshwater outlets. It is clear that Bolgoda Lake is apparently a disposal site of various discharges of factories in addition to poor drainage and sewage systems present in this area. Highly unplanned urbanization and absolutely lack of adequate waste disposal management facilities in industries close to Lake have resulted in pollution of water. If the present trend of waste disposal and unplanned urbanization continue, they would create enormous environmental problems in future. Results of the present study showed that information from satellite remote sensing can play a useful role in determining the changes in Chl-a related to eutrophication in Bolgoda Lake and in the development of time series Chl-a distribution maps. Such information is important for the future predictions, development and management of this area as well as in the conservation of biodiversity. Therefore we recommend incorporation with this technique for routine monitoring of water quality using multi satellite data such as ASTER in inland water bodies like Bolgoda Lake in the future.Item Integration of multisource data for chlorophyll-a monitoring in Negombo estuary, Sri Lanka(IEEE, 2011) Dahanayaka, D.D.G.L.; Tonooka, H.; Wijeyaratne, M.J.S.; Minato, A.; Ozawa, S.In order to estimate chlorophyll-a concentration (Chl-a) for tropical coastal estuarine environments using satellite optical sensor, observations were conducted from 1987 to 2009 in Negombo estuary, Sri Lanka, with support with available in-situ measurements. Landsat band ratios were regressively analyzed with available in-situ Chl-a data. This relationship was used for correcting MODIS OC3 Chl-a values, and then ASTER band ratios were regressively analyzed with the corrected MODIS values. The regression equations obtained for ASTER and Landsat were used to develop algorithms for generation of 15m and 30m resolution Chl-a distribution maps, respectively, in Negombo estuary using atmospherically-corrected time-series imageries. The results indicate that some parts of the estuary have increased eutrophication conditions during 1987-2009.Item Development of coastal water body database on KISSEL server(IEEE, 2012) Dahanayaka, D.D.G.L.; Tonooka, H.; Wijeyaratne, M.J.S.; Minato, A.; Ozawa, S.Monitoring of coastal water bodies in all the relevant aspects was highly important for the sustainable use of those. To achieve this all the research findings should be easy access and presenting those in a user friendly manner will be more advantage. In Sri Lanka, there was not fully or never developed database on research findings especially on coastal water bodies. Thus we developed a Sri Lankan coastal water body database (CWBDS) on KISSEL server system which can be benefitted all the interest communities including general public. Presently it include water quality data over two decades of lagoons and estuaries and in near future it will update with support from universities and research organizations including research on biodiversity, fisheries, land use, socio economics, topography, water circulation, pollution etc.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 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.