Browsing by Author "Wijeyaratne, W.M.D.N."

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Abundance-Biomass Comparison approach to assess the environmental stressors in Diyawannawa wetland in monsoonal and non-monsoonal seasons
(Sri Lanka J. Aquat. Sci, 2018) Wijeyaratne, W.M.D.N.; Bellanthudawa, B.K.A.
Abundance-Biomass Comparison (ABC) approach is a graphical approach that compares the abundance and biomass of organisms in order to predict the environmental stress level of an ecosystem. The present study was conducted in selected sites located at non-rehabilitated and rehabilitated areas of the Diyawannawa wetland in Sri Lanka in the monsoonal and non-monsoonal seasons. The ABC was performed on the macrobenthic mollusk species collected from the study sites. Eight species of macrobenthic mollusks, namely, Bithynia tentaculata, Melanoides turbeculata, Melanoides turriculus, Thiara scabra, Lamellidens marginalis, Pila globosa, Gyraulus saigonensis and Lymnaea stagnalis were recorded during the study period. Based on Principal Component Analysis, B. tentaculata, and, P. globosa were identified as characteristic gastropod species that could be used to classify study sites in the rehabilitated and non-rehabilitated areas of this tropical wetland system. In the monsoonal season, overlapping cumulative percentage dominance of abundance and cumulative percentage dominance of biomass curves in sites A, B, and F indicated partially disturbed environmental conditions. The site C of the non-rehabilitated area, showed a typical undisturbed condition and the sites D and E of the rehabilitated area the cumulative percentage dominance of biomass curve was located above the abundance curve, indicating disturbed environmental conditions in these sites during monsoonal season. During the non-monsoonal season in all the sites except site F of the rehabilitated area, the cumulative percentage dominance of abundance curve was located above the biomass curve, indicating undisturbed environmental conditions in these sites. In the site F, the cumulative percentage dominance of abundance and the cumulative percentage dominance of biomass curves were crossing each other, indicating partially disturbed environmental conditions at this site. The values of the W statistic, which ranged from 0.004 to 0.374 in the non-monsoonal season and ranged from 0.1 to 0.2 in the monsoonal season, and pollution and water quality categorization by modified biotic index (MBI) were in agreement with the results of the ABC approach.
Acetylcholinesterase inhibition and gill lesions in Rasbora caverii, an indigenous fish inhabiting rice field associated waterbodies in Sri Lanka
(Kluwer Academic Publishers-Plenum Publishers., 2006) Wijeyaratne, W.M.D.N.; Pathiratne, A.
The present study was aimed at applying condition factor (CF), brain acetylcholinesterase (AChE) and gill histology as biomarkers for detecting possible exposure/effect induced by pesticides in fish residing rice field associated waterbodies in Sri Lanka. Biomarkers of an indigenous fish, Rasbora caverii collected from five sampling sites including canals near rice fields, a river and a reservoir (the reference site) were evaluated at four sampling stages covering pesticide application periods during rice cultivation season in 2004. Results indicated that CF of the fish did not show significant alterations regardless of the sampling sites or sampling stages. Site specific differences in AChE activities of the fish were not evident either prior to application of pesticides or at 7 days after Paraquat application to the rice fields. Two days after the application of a mixture of Fenthion and Phenthoate to the rice fields, AChE activity of the fish collected from canals near rice fields was significantly depressed (65–75%) compared to the fish in the reference site. The activities remain depressed to 50–56% even at 65 days after the insecticides application. Laboratory studies showed that prior exposure of R. caverii to Paraquat (2 μg l−1, 7 days) enhanced the extent of inhibition of brain AChE activity induced by Fenthion (3 μg l−1) or a mixture of Fenthion (3 μg l−1) and Phenthoate (5 μg l−1). Gills of fish collected from canals near rice fields exhibited abnormal multiple divisions at the tips of some secondary lamellae in addition to hyperplasia, hypertrophy and club shaped deformities. Results indicate that application of pesticides in rice culture could manifest a threat to native fish populations residing rice field associated waterbodies. The response of brain AChE and histological changes in the gills of R. caverii allowed differentiating sampling sites after insecticide applications to the rice fields. Hence, R. caverii may be considered as a surrogate species in ecotoxicological risk evaluation of agrochemicals in the region.
Acetylcholinesterse inhibition and gill lesions in Rasboracaverii, an indegeneous fish inhabiting rice field associated waterbodies in Sri Lanka
(Ecotoxicology, 2006) Wijeyaratne, W.M.D.N.; Pathiratne, A.
Application of home remedial techniques to reduce hardness and Assessment of Variation of physical and chemical parameters of well water in Vadamaradchi
(Wetlands Sri Lanka 2018, 2018) Suvendran, S.; Wijeyaratne, W.M.D.N.
Vadamaradchi aquifer is considered to be the best ground water source in Jaffna peninsula. Therefore, some wells in Vadamaradchi are used as collector wells which supplies water to fulfil domestic water requirements of the residents in Jaffna peninsula. The present study was conducted with the objectives of assessing physical and chemical parameters of water in selected wells in Vadamaradchi and to identify suitable home remedial techniques to treat the increased hardness of water. Variation of physical and chemical parameters of water collected form 10 collector wells in Vadamardchi aquifer were analyzed and were compared with those parameters in bottled drinking water (Knuckles brand) and with SLSI drinking water quality standard. Along with that the replicate water samples collected were subjected to boiling at 1000C for 10 minutes, filtration through commercial mineral filter and Moringa oleifera leaf powder filter. Total hardness (254.4 mg/L) of the collector wells exceeded the SLSI drinking water standards. Filtration through Moringa oleifera leaf powder filter significantly increased TH and filtration through commercial mineral filter did not caused a significant reduction in TH. However, boiling water at 1000C for 10 minutes significantly reduced TH accounting for 16 % reduction.
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.
Assessing the environmental stress in the Diyawannawa wetland using macro-benthic molluscan diversity based Abundance-Biomass Curves
(Sri Lanka Association for the Advancement of Science Proceedings of the 73rd Annual Sessions, 2018) Bellanthudawa, B.K.A.; Wijeyaratne, W.M.D.N.
The present study assessed the variation of macrobenthic molluscan abundance and biomass with spatial variation of water and shallow sediment quality parameters in the rehabilitated and nonrehabilitated regions of the Diyawannawa wetland. Six sampling sites, reflecting various land uses in the non-rehabilitated (Site A,B,C) and rehabilitated (Site D,E,F) areas of the Diyawannwa wetland, were selected. At each site, DO, nitrate concentration, total phosphate (TP) concentration, BOD5, COD, chlorophyll-a (Chl-a) concentration of water, sediment conductivity, sediment pH, sediment percentage organic matter (%OM), sand%, silt%, clay%, and abundance and biomass of macrobenthic molluscs were recorded. Sampling was done from April to October 2016. One way ANOVA followed by Tukey’s pairwise comparison was used to assess the spatial variation of water and sediment quality parameters. The correlation between macrobenthic mollusc abundance and water and sediment quality parameters were determined by Pearson’s correlation analysis. Abundance- Biomass Comparison (ABC) Curves of molluscs were plotted. The significantly high mean abundance of Bithynia tentaculata (35), Melanoides turbeculata (5), Lamellidens marginalis (3) and Pila globosa(2) were recorded in site F, of the rehabilitated area where there was a significant input of solid waste, runoff sediments and organic matter. A significant spatial variation of nitrate N, COD, BOD5, Chl-a, DO, % sand, % OM, sediment pH, and conductivity was recorded in rehabilitated sites. Significantly high mean nitrate, Chl - a, COD, and % OM were recorded in site F. Bithynia tentaculata and Pila globosa showed a significant positive correlation with shallow water Chl - a, nitrate content, TP, COD and BOD5;Bithynia tentaculata was the biomass dominant species in all sampling sites. The highest and lowest percentage of biomass of Bithynia tentaculata was recorded in Site F (78.13 %) and in Site B (41.40%) respectively. The ABC curves indicated Site A as a typical unstressed site while Site F as a heavily stressed site. All the other sampling sites were moderately stressed and the level of disturbance varied among the sites. Further based on water and sediment quality data, it can be concluded that most of polluted sites (Sites E and F) are in moderate to heavily stressed condition, while comparatively less polluted sites (Sites A to D) are in unstressed to moderate stressed condition.
Assessment of drinking water quality of domestic wells in Chunnakam and Vadamaradchi, Jaffna peninsula
(Sri Lanka Association for the Advancement of Science Proceedings of the 73rd Annual Sessions, 2017) Suvendran, S.; Wijeyaratne, W.M.D.N.
An assessment of the quality of drinking water was carried out by measuring 12 selected physicochemical parameters for selected domestic wells in Chunnakam and Vadamaradchi areas of Jaffna. Vadamaradchi is used as the reference site, as this area is considered to have the best fresh water in Jaffna peninsula. The measured physico-chemical parameters of water from selected domestic wells were compared with the standards established by World Health Organisation (WHO) and Sri Lanka Standards Institution (SLSI) for drinking water. Spatial and temporal variation of parameters among sites was analysed using Two-way ANOVA. The characteristic water quality parameters of the sampling sites were identified using Principal Component Analysis (PCA). Significantly high concentrations of nitrate and oil & grease were recorded in Chunnakam (p<0.05), whereas significantly high dissolved oxygen (DO) and pH were recorded in Vadamaradchi. Nitrate concentration of the wells ranged between 0.021 – 40.1 mg/L, while 30% of these wells exceeded WHO permitted nitrate standard level, 11mg/L. Oil & grease (OG) of the wells ranged from 0.011 to 0.373mg/L, while 70% of wells in Chunnakam exceeded the SLSI permitted standard limit for OG, 0.2mg/L. A significant temporal variation of DO, total solids and total hardness was recorded in Chunnakam, while pH, DO and total phosphorus showed significant (p<0.05) temporal variations in Vadamaradchi. The wells in Vadamaradchi were characterized by high DO, low nitrate, and low OG, while the wells in Chunnakam were characterized by high nitrate and OG. The values recorded in the current study can serve as baseline values for future water quality monitoring and management studies in Chunnakam and Vadamaradchi.
Assessment of water eutrophication in selected locations of the Diyawanna Oya using chemical assessment methods
(Department of Zoology and Environmental Management, University of Kelaniya, Sri Lanka, 2017) Samarawicrama, L.D.R.; Sanjeevani, K.S.; Sammani, D.G.P.; Rathnayake, A.K.V.H.; Wijeyaratne, W.M.D.N.
Eutrophication is one of the most widespread environmental problems of inland water bodies of Sri Lanka. It has lot of negative impacts on the aquatic ecosystems including increased biomass, growth of harmful algal species, decrease in water transparency, changes in the biodiversity and effects on the aquatic food web. In addition, eutrophication can cause serious health effects in humans and domestic animals. Diyawanna oya is one of the major water body situated in Kotte area that is currently showing signs of eutrophication and many problems associated with it. The objectives of the case study were to compare BOD levels, COD levels, Chlorophyll a, and NO3- and PO43- levels in selected three sites of Diyawanna Oya with Sri Lankan water standards and to compare physical parameters such as Temperature, pH and Visibility in three selected sites over wet, dry and intermediate seasons. Three sites were selected for the study and, sites 1 and 2 were rehabilitated sites while site 3 was a non-rehabilitated site. BOD5 of the study sites ranged from 5.5-8.0 mg/L which is higher than the permissible threshold limit (>5 mg/L).The COD value of tree study sites during the period of case study was between 15.501- 41.670 mg/L, The nitrate concentrations of the three study sites varied between 1.3 – 2.5 mg/L during the period of study while the phosphate concentration varied between the values of 8.8 – 50 mg/L. Higher BOD values and Chlorophyll a were observed in sites 2 and 3 and higher values for COD and nitrate concentrations were observed in sites 1 and 2 meanwhile higher level of phosphate concentrations were observed in all three sites. Many of the readings obtained exceeded the highest permissible threshold limits that should be present in inland water bodies of Sri Lanka. Chlorophyll a level in the selected three study sites were in the range of 3.11 – 29.82 mg/L. The water temperature of the three study sites were between 310C – 340C and the pH ranged from 7.64 – 8.57 showing a slight alkaline conditions in the water of the study sites. Visibility was relatively low in all three selected study sites during the study period. According to the results it was noted that Eutrophication in Diyawanna oya cannot be monitored using only chemical assessment. Regular visual assessments accompanied with routinely chemical analysis of water quality can help in maintaining and keeping eutrophication of Diyawanna oya at controlled condition. By taking proper regulatory, control methods Diyawanna oya and the ecosystem that is bound with it can be protected.
Assessment of water eutrophication in selected locations of the Diyawanna Oya using visual assessment method
(Department of Zoology and Environmental Management, University of Kelaniya, Sri Lanka, 2017) Samarawicrama, L.D.R.; Sanjeevani, K.S.; Sammani, D.G.P.; Rathnayake, A.K.V.H.; Wijeyaratne, W.M.D.N.
Diyawanna Oya is one of the precious assets in the Colombo metropolitan of Sri Lanka. Some parts of Diyawanna oya is currently under the threat of eutrophication due to rapid development and urbanization of the area. There is a large number of low income houses and several large scale apartment complexes in close proximity to Diyawanna oya. Quality of water and habitat in most of the areas is mainly influenced by public effluent discharges to the canal system, which has a significant environmental effects on the wetland. The objectives of the case study were to use the visual assessment method to compare the levels of eutrophication and to identify the perspectives of the local community on the eutrophication. Three sites were selected for the study and, sites 1 and 2 were rehabilitated sites while site 3 was a non-rehabilitated site. Replicate water samples were collected from each site to cover wet and dry seasons. In visual assessment, presence of Pheriphytons , Phytoplankton, Free floating aquatic plants, Rooted submerged plants, color and odor of water was ranked according to standard visual assessment criteria. Face to face interviews using a questionnaire were carried out by interviewing 40 individuals in the local community. Considerable amount of Pheriphytons, Phytoplankton, Free floating aquatic plants, Rooted submerged plants were observed in sites 1 and 2 while site 3 indicated an elevated level of phytoplankton. The community survey revealed the lack of knowledge of the respondents on eutrophication is the major cause for eutrophication associated problems. The results of the community survey revealed that, majority of the respondent population (74.6%) that lives close proximity to Diyawanna oya does not use the water that can be obtained from that water body for any commercial activity as a result of heavy water pollution, lack of cleanliness and hygiene , but few people (25.6%) uses water that can be obtained mainly for washing vehicles and for fishing activities During the survey it was noted that the residents of the area have frequently suffered from various skin diseases (especially during the rainy season) and vector borne diseases such as Dengue and Filariasis. Majority (59%) of the respondents were not aware of the animal kills associated with eutrophication and related problems. While (41%) expressed observation of fish and bird kills from time to time. The results of this case study shows that Diyawanna oya is heavily polluted with sewage, domestic organic waste and cleaning materials. The pollution is worsened due to over population, urbanization, decrepit infrastructure, inadequate cleaning programs and malfunctioning in the existing programs and also due to breaches in local government management system. The results of this study highlights the immediate control measures to overcome the environmental impacts of eutrophication in Diyawanna oya.
Biological remedies towards safe water...
(Proceedings of the Twenty Fourth Scientific Sessions of the Sri Lanka Association for Fisheries and Aquatic Resources, 2018) Wijeyaratne, W.M.D.N.
Water is considered as the most essential component in the human livelihood. Rapidly increasing world population, mainly in the developing countries in parts of Asia, North Africa and the Middle East, and sub-Saharan Africa have placed an inordinate demand on safe drinking and potable water. This ever increasing water demand have exceeded the avaiiabie suppiy oi safe fresh water in many regions oi the world. Some major river basins in Asia, North Africa and Middle East are facing severe water scarcity, and over extraction of ground water resources has become a growing problem in many parts of the world. The water scarcity problems are further intensified by increased water pollution due to point and non-point source inputs from urban, industrial and agricultural sectors. Water pollution has imposed severe health issues on human populations and ecological health impairments in aquatic ecosystems. Ensuring universal access to affordable and safe drinking water by 2030 is a target in one of the sustainable development goals. Therefore, the national and international efforts are being initiated to improve water purification infrastructure, provide proper •sanitation facilities, and encourage hygiene in rural, urban and sub urban communities. In addition, the importance of protection and restoration of water- related ecosystems such as forests, mountains, wetlands and riversäs identified in- order to mitigate water scarcity. However, the costs of treating polluted water and restoring water bodies has become a major concern in many countries. The cost of water treatment and aquatic ecosystem restoration requires investment of large amounts of funds and labor, which is unbearable by most of the developing and technology lagging countries. Therefore, natural and synthetic remediation methods have been studied to improve the quality of the contaminated water in many parts of the world, Compared to the chemical purification methods, use of natural materials is increasingly popular among many research groups as these methods provide more cost-effective, environmentally friendly alternatives of water purification. Biological water purification methodologies can be in treatment of domestic drinking water as well as for treating waste water before releasing thém to the environment. Many traditional water purification methodologies that have in practice for decades have been improved and modified by recent research findings to cater for wider community in need of purified water. Further, Many research have been to identify effective plant and microbial aggregations that can serve as universal communities in constructed wetlands in terms of remediation of heavy metal, suspended solids and nutrient pollution. treatment increasing'} researched 2nd as they can destroy and remove multiple contaminants simultaneously and have minimum sludge production and bacterial regrowth. Biological treatment can be used to remove natural organic matter, cclour, chloroform, perchlorate, nitrate, nitrite, bromate, iron, manganese, chromate, arsenate, and a variety of other contaminants cf polluted y.'2ter . cy.id2ticn prier to filtraticn cr settling, as wetl as the need for chemical reduction methods, and produces innocuous end-products, thus reducing the risk Of a contaminating the natural aquatic systems. Therefore, to achieve the sustainable development goal of ensuring availability and sustainable management of water and sanitation for all by 2030, the importance of the role of living organisms in water purification needs to be given a top priority as life and water is the driving force towards a sustainable future.
A case study to assess the possibilities of electrical energy conservation in an office premises
(Department of Zoology and Environmental Management, University of Kelaniya, 2015) Mendis, K.T.N.; Madushani, D.L.; Merinsa, J.; Kapilarathna, K.; Wijeyaratne, W.M.D.N.
Composting potential of kitchen waste generated from the canteen. A case study in the Faculty Science, University of Kelaniya
(Department of Zoology and Environmental Management, University of Kelaniya, 2015) Vathani, A.S.A.; Dinushika, L.G.T.; Shanika, W.P.; Siriwardhana, S.M.N.P.; Wijeyaratne, W.M.D.N.
Cyto-genotoxicity and quality of sediments in Dandugan Oya, Sri Lanka
(Proceedings Of Tile 38th Annual, Sessions Of The Institute Of Biology, 2018) Wadasinghe, L.G.Y.J.G.; Wijeyaratne, W.M.D.N.
Sediments are very important in maintaining aquatic ecosystem health. Dandugan Oya is a stream located in the Western province of Sri Lanka. Dandugan oya receives industrial waste from multiple sources. It also serves as a raw water source for public water supply in some suburban areas in the Gampaha District. This study was conducted with the objective of assessing sediment quality and cyto-genotoxic effects of sediments in Dandugan oya. Shallow sediments (5 replicates) were collected from six sites CA: Urban site; B and D: Industrial sites; C: water intake for public water supply; E: Agricultural site; F: Reference site) at two month intervals from May to November 2017 and sediment quality was analysed using standard analytical methods. Cyto-genotoxicity of the sediment elutriates were assessed using Allium cepa bioassay. Spatial variation of sediment quality and toxicity indices were analysed by ANOVA followed by Tukey's pairwise comparison using MINITAB 14 software. Significant spatial variations of sediment quality parameters and nuclear abnormalities were observed. Site B recorded significantly lower sand (37%) and significantly higher silt contents (44%) while site D showed a significantly higher clay content (40.6%). Significantly lower sediment pH (4.71) and sediment conductivity (25.29 VLS/cm) were recorded from reference site and highest total organic matter (2.32 %) content was recorded at urban site. Mean nuclear abnormalities ranged from 130/00 to 440/00 with significantly higher abnormalities in sites B (42%)) and D (440/00). Occurrence of nuclear buds and condensed nuclei in the interphase cells of the Allium cepa root tips exposed to sediment elutriates from industrial sites (150/00 and 180/00) were significantly higher (7 to 9 fold) compared to reference site. Further, Site B showed the highest condensed nuclei formation (610/00). However, occurrence of binuclei showed no significant spatial variations, The Mitotic index of the Allium cepa root tip cells ranged from 2.9% to 7.4% with significantly higher values in sites A and B, The results of the present study indicated the occurrence of potential cyto-genotoxic contaminants in the sediments of Dandugan Oya. Therefore, further investigations on the identification of the active forms of these contaminants are recommended in order to maintain the health of the ecosystem.
Diversity in the Diyawannawa wetland
(Department of Zoology and Environmental Management,Faculty of Science, University of Kelaniya Srilanka, 2021) Nanayakkara, D.B.M.; Wijeyaratne, W.M.D.N.
Evaluation of the effects of three commonly used pesticides on brain Acetyl cholinesterase activity of Rasbora caverii, a feral fish found in paddy field associated water bodies in Sri Lanka
(Sri Lanka Association for Fisheries and Aquatic Resources, 2005) Wijeyaratne, W.M.D.N.; Pathiratne, A.
Gill leisions in Rasbora caverii (Class: Pisces, Family: Cyprinidae) inhabiting paddy field associated water bodies in Kaduwela area, Sri Lanka
(Sri Lanka Association for Fisheries and Aquatic Resources, 2005) Wijeyaratne, W.M.D.N.; Pathiratne, A.
Identification of Macrophyte Indicator Species to Evaluate the Water Quality in Wetland
(Proceedings of the 22nd International Forestry and Environment Symposium 2017, 2017) Bellanthudawa, B.K.A.; Wijeyaratne, W.M.D.N.
Present study conducted to assess the SP?ti?! yeri?tion of mecrophvte distribution 2nd water quality parameters of a rehabilitated and non-rehabilitated areas of the Diyawannawa wetland with the aim of identifying suitable macrophyte indicator species for water quality monitonng. Sites A, B and C were located in non-rehabilitated area and the sites D, E and F were located in rehabilitated areas in Diyawannawa wetland. The sampling was conducted from April to October 2016. At each site, water pH, temperature, conductivity, sa!inity, total dissolved solids (TDS), dissolved oxygen concentration (DO), biological oxygen demand (BOD5), chemical oxygen demand (COD), depth, visibility, total nitrate (TN), chlorophyli a (Chl a) and total phosphorus (TP) concentration were measured and the percentage cover of macrophytes were recorded. The correlation of percentage cover of macrophyte species to the water quality parameters were assessed using Pemson's correlation analysis. Principal component Analysis (PCA) based on the percentage cover of macrophyte species was performed to identify the characteristic species at each site. M[NITAB 14 software was used for statistical analysis ofdata. The percentage cover of Hydril/a verticil/ata, Pistia straiiotes and Cypreus iria did not show significant spatial variations among rehabilitated and non-rehabilitated areas. Significantly high percentage cover of Nymphaea ampla (64%) and Annona glabra (l I %) were recorded in site A in non-rehabilitated area. Eichhornia crassipes (22%) showed significantly high percentage cover in site B in non- rehabilitated area and site E in rehabilitated area. Cryptocoryne wendtii recorded significantly high percentage cover In sites A (10%) and E (7%), The highest mean percentage cover of Salvinia ;nolesta (30%) were recorded in site E. The spatial variation of physico chemical parameters Indicated significantly high DO in sites E (10.61 mg/l) and F (10.28 mg/l). Significantly high Chl a concentrations were recorded from sites B, E and F. In addition, site F recorded significantly high BOD5 (6.56 mg/l), TN (0.04 mg/l) and COD (454.8 mg/l). There was no significant spatial variation of TP among sampling sites. S. molesta and E. crassipes showed positive correlations with Chl a and TP and N. rubra showed a positive correlation with TN. H. verticillata and P. stratiotes did not show significant correlations with water quality parameters. According to PCA, considering PC scores I to 3, site A in the non-rehabilitated area was characterized by N. ampla and C. wendtii, site B by E. crassipes and P. stratiotes and site C by A. glabra. In rehabilitated area, site D was characterized by C. iria and Ceratophyllum demersum, site E by S. molesta and site F by N, rubra. The PCA based on water quality parameters grouped the sites E and F together and were characterized by high TN and Chl a concentrations. The results of the present study indicated that there is significant spatial variation of percentage macrophyte cover in relation to water quality parameters. Further, this study identified S. molesia and Eichhornia crassipes and N. rubr.a as suitable indicator of Chl a and TP and TN in wetland health monitoring studies.
In vitro study on bio removal of cadmium (CD2+) by freshwater cyanobacterium Oscillatoria sp. And its isotherm
(Department of Forestry and Environment Science, University of Sri Jayewardenepura, Sri Lanka., 2016) Wijesekara, W.A.M.A.; Wijeyaratne, W.M.D.N.; Manage, P.M.
Monitoring of water quality variation trends in a tropical urban wetland system located within a Ramsar wetland city: A GIS and phytoplankton based assessment
(Environmental Nanotechnology, Monitoring & Management, 2020) Wijeyaratne, W.M.D.N.; Nanayakkara, D.
The present study, was conducted in an urban wetland system within a Ramsar wetland city in Sri Lanka to study the effectiveness of using the Geostatitical and multivariate statistical techniques together with phytoplankton based biological indices to assess the wetland ecological status. Seven sites were selected from the wetland and the water quality parameters and the diversity and abundance of phytoplankton at each site was assessed. Thirteen species of phytoplankton from Class Cyanophyceae, 18 species from Class Chlorophyceae and six species from class Bacillorphyceae were recorded during the study. There were significant spatial variation of water quality parameters and phytoplankton composition among the study sites. Principal component analysis for water quality and phytoplankton distribution was performed. Palmers index, percentage biological index and the limnological condition index was calculated based on water quality and phytoplankton data. According to the classification based on Palmers index the sites located in the northern portion ofthe wetland indicated high organic pollution, while otier sites indicated no or less less organic pollution. According to the limnological categorization based on pollution index, %BI and LICOI, the northern sites were categorized as sites with poor ecological quality and as severely contaminated sites. The sites in the southern portion of the wetland were categorized as moderately polluted sites with acceptable limnological conditions for the ecologicaI functions to occur within tolerable limits. Water quality prediction maps for the wetland was developed using geostatistical methods and the water quality trends also agreed with the results of the biological indices and the results of the multivariate statistics. The results indicated that the geostatisical and multivariate techniques together with the Palmers index, percentage biological index and the limnological condition index can serve as important tools for monitoring the water quality trends in tropical urban wetland ecosystems.
Spatial variation of microbenthic community in relation to water and sediment quality parameters in the Ja-Ela canal, Sri Lanka
(The Institute of Biology, Sri Lanka, 2016) Kalaotuwawe, K.M.B.P.P.; Wijeyaratne, W.M.D.N.