Browsing by Author "Thilakarathne, E.P.D.N."
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Item Assessment of Coral Health along the Eastern Coast of Sri Lanka(Uva Wellassa University of Sri Lanka, 2020) Balasooriya, L.B.A.K.S.; Thilakarathne, E.P.D.N.; Abeygunawardana, A.P. A; Egodauyana, K.P.T.U; Malshani, P.K.T.Corals are called as most diverse and valuable ecosystems on the earth, disclose their productivity and ecological benefits. Today coral community is degraded and diseases are the distinguishing factor that affects coral health conditions. Absence of the proper health level with any kind of abnormalities called as a disease. In the sense of the view, some are infectious and others are not (genetically-based or toxicant-induced disorders). Lesions or mutations and significant color changes occur due to disease of the coral reefs. Since there is no scientific health assessment on reefs in Sri Lanka has been undertaken to this date, a study was carried out in the final quarter of 2019, using visual observation method by snorkeling and diving over transect lines of most significant & prime fringing coral reefs; Passikudha, Kayenkerni, Adukkuparu, Parrot rock and Pigeon Island reefs of the Eastern coast. 30 transect lines consisted of 50 m length were surveyed per site. The result of the study showed that 07 coral diseases from the Eastern coast were identified under Tissue Loss, Tissue Discoloration, Growth Anomalies and Compromised Health disease categories. 104 of coral species were recorded under 13 families and 65 species out of them were possessed any kind of diseases. All coral reefs were highly threatened due to “compromised health problems and tissue discoloration (white; bleaching) diseases. Most disease vulnerable coral families were, Acroporidae, Agariciidae, and Pocilloporidae. Acropora valenciennesi, Coeloseris mayeri, and Pocillopora damicornis from each family encounter the higher correlation with disease vulnerability. Adukkuparu and Parrot rock reefs were respectively the most and least diseased sites. Considerable natural and disagreeable anthropogenic effects may be the reason for these utmost outbreed health problems. Augmentation of ecosystem management and conservation plans with more researches on health issues may help to protect above coral communities. Keywords: Coral diseases, Tissue loss, Tissue discoloration, Compromised health problems, Natural and anthropogenic effectsItem Cetacean Diversity, Encounter Rates, and Behavior in Whale-Watching Waters off Southern Sri Lanka(Uva Wellassa University of Sri Lanka, 2021) Sankalpa, D.M.R.; Thilakarathne, E.P.D.N.; Li, Songhai; Kumarasinghe, C.P.Data on the diversity, encounter rates, and behavior of cetaceans is vital to the conservation and the management of whale-watching activities. The southern coast of Sri Lanka is distinguished with a continental shelf, extremely steep slope, and deep submarine canyons. Though cetaceans are known to be abundant in these waters, there is a dearth of up-to-date data pertaining to the relative abundance, and species occurring in the whale-watching waters off Mirissa. Data collected during rapid boat-based cetacean surveys following the random line transects from January to May 2017 were analyzed to investigate the diversity, encounter rates, and behavior of cetaceans in the waters off Mirissa, covering a total of 788.9 km2 survey area. During the 55 survey days, nine species were recorded: Balaenoptera musculus, Balaenoptera omurai, Balaenoptera edeni, Stenella longirostris, Physeter macrocephalus, Tursiops truncates, Globicephala macrorhynchus, Peponocephala electra, and Orcinus orca. The Simpson diversity index for the entire study area was 0.5 and the encounter rate for the entire study area was 16.5 sightings per 100 km. Traveling and foraging behavioral states were frequently observed in large whales while socializing was observed in small toothed whales and the dolphins in the present study. Additionally, it is noteworthy that the temporal changes of the sightings of small toothed whales and the large whales were inverse, reflecting sequential use of the Mirissa waters by different species to reduce interspecies competition. However, the study also found differential regional preferences among cetaceans as common bottlenose and spinner dolphins being sighted mostly in inshore waters (< 500 m isobaths), while large whales (blue whales and sperm whales) being more frequently sighted along the continental slope (> 500 m isobaths). It was also observed that blue whales were feeding along the outer shelf and high slope waters where a major shipping route is crossing. This study further recommends that implication of proper management strategies for conservation and sustainable whale-watching activities are needed. Keywords: cetaceans; encounter rates; diversity; Sri Lanka; diversity indexItem Comparative Assessment on Non-Indigenous Biofouling Species in Colombo Harbour Basin with Ships Arrive to the Colombo Harbour(Uva Wellassa University of Sri Lanka, 2020) De Silva, N.K.L.; Thilakarathne, E.P.D.N.; Gunasekara, A.J.M.Introduction of non-indigenous aquatic organisms to the new environments through ships biofouling has been identified as a major threat to world oceans and for the conservation of biodiversity. As an island nation with intensive shipping activities, there is a high possibility to introduce invasive species into Sri Lanka through ships biofouling. It is imperative to identify and assess the fouling related invasions in Sri Lankan waters to adopt necessary control measures. This study examined the biofouling related invasion in Colombo port with a view of adopting control measures. The study was undertaken between October 2019 to January 2020 in Colombo port. The hard substrate samples were collected monthly basis from eight sampling locations. The artificial settlement plates were deployed to collect benthic fouling samples. Samples were collected from the ship’s hull which arrived at the Colombo port from various regions of the world. 93 biofouling creatures were identified up to their family level and 83 up to their species level. 51% nonindigenous, 35% native, and 4% cryptogenic fouling species were detected. 33 native fouling organisms were detected from all samples. Relative abundance, diversity indices, species richness, and evenness were calculated. Mean relative abundance varied with 0.0169 to 0.0579. Amphibalanus amptrite the most abundant species on ship’s hull while Saccostrea cucullata was the most common species at harbour sites. The exotic species of Chathamalus montagui was recorded for the first time in Colombo harbour. The five globally known invasive alien species introduced through ships were recorded. Results imply that some invasive biofouling species had already settled in the harbour basin area and ships arrive in Colombo port poses a risk of introducing invasive species into Sri Lanka waters. This study suggests that it is exigent to adopt relevant international guidelines to mitigate the threat of introducing invasive species through ship biofouling. Keywords: Invasive alien species, Biofouling, Colombo port, Ship's hull, IntroducingItem Efficiency of Manganese Removal by Eichhornia crassipes and Pistia stratiotes from Contaminanted Water(Uva Wellassa University of Sri Lanka, 2019-02) Jayawardhana, I.D.S.T.; Athula, J.A.; Thilakarathne, E.P.D.N.Metal pollution is a major problem of water sources used for drinking purposes. Among heavy metals, Manganese (Mn) is an essential trace element for the functioning of human, animal and plants but it leads to toxicity when it exceeds the standard level. Phytoremediation can be applied to remove heavy metals from aquatic environment. Floating aquatic macrophytes are used as an environmental friendly, efficient and cheap method. In presence study two aquatic plant species, Eichhornia crassipes (Water Hyacinth) and Pistia stratiotes (Water Lettuce) were used to determine the efficiency of removing Manganese. Bioassays using Water Hyacinth and Water Lettuce were carried out with de-ionized water contaminated by three concentration series (20, 40, 60 mg L-1) of Manganese (Π) for a period of 24 days. Three replicates were carried out for each series. Water samples were taken from each series at one day intervals and remaining manganese were analyzed using Atomic Absorption Spectrometry technique. Variations of pH and electrical conductivity of water were also measured as same interval by standard techniques. Data were statistically analyzed using SPSS16.0 package. Both Eichhornia crassipes and Pistia stratiotes showed the highest removal efficiency at the lowest concentration of Manganese (20 mg L-1). Average efficiency of manganese removal from water by Eichhornia crassipes and Pistia stratiotes were 67.61% and 80.04% respectively. Higher manganese removal efficiency was observed in Pistia stratiotes than Eichhornia crassipes. There was a significant difference (p<0.05) between absorbed manganese concentrations with the time in Eichhornia crassipes, but there was no significant difference (p>0.05) in Pistia stratiotes. The results of the study revealed that the both plants can be used to remove manganese from contaminated water. However, it is needed to conduct a pilot study for the water contaminated with manganese.Item Fluctuation of Sea Surface Temperature (SST) Over Shallow Coral Reef Ecosystems in Eastern Coast of Sri Lanka During the Past 15 Years Period(Uva Wellassa University of Sri Lanka, 2021) Sewwandi, S.W.R.; Thilakarathne, E.P.D.N.; De Silva, P.Coral reefs are dynamic and complex marine habitat which are highly sensitive to elevated Sea Surface Temperature (SST) than their optimal maximum temperature (27°C). Elevated SST directly affects coral bleaching and services they provided. Satellite remote sensing data can be effectively and efficiently used for spatial and temporal analysis of SST. The 1km Multiscale Ultrahigh Resolution (MUR) Level 4, SST data from NASA from 2005 to 2020 (15 years) were used for this study. Highly biodiverse and popular shallow reefs (<10m) along the Eastern coast i.e., Pigeon Island, Parrot Rock, Adukkuparu, Kayankerni and Passikudha were selected for this study. The area of reefs extended less than 10m water depth were demarcated by field surveys followed by polygon layers created by Google Earth Pro (7.3.3). The annual average SST for the period of 2005-2020 were as 28.95°C, 28.96°C, 28.71°C, 28.71°C, 28.71°C respectively. They will be expected as 29.29°C, 29.29°C, 29.31°C 29.39°C, 29.75°C by 2030 and may cause the extinction of most of the remaining live corals. Predominantly extreme SST recorded between 30°C to 31°C in April to May in 2010, 2016 and April to June in 2019 due to El Niño conditions and they were more severe in Kayankerni reef (30.23°C, 30.18°C in 2010 and 30.60°C, 30.30°C in 2016 and 30.86°C, 30.75°C, 30.75°C in 2019) and Passikudha reef (30.23°C, 30.23°C in 2010 and 30.60°C, 30.30°C in 2016 and 30.87°C, 30.87°C, 30.79°C in 2019). In addition, the mean SST levels recorded in the East coast during the Northeast monsoon period and the Southwest monsoon period were Significantly different (p<0.05). During the past fifteen years period, the mean SST value during the Southwest monsoon (May to September) was calculated as 29.22°C and the mean SST value during the Northeast monsoon (December to February) was 27.48°C. The mean SST for Southwest monsoon differs 1.74°C from mean SST in Northeast monsoon. Therefore, these findings are highly important when implementing coral conservation and replanting projects in particular areas and declared areas as seed banks to replenish more susceptible site. Keywords: Coral bleaching; Satellite remote sensing data SST; Thermal stress; El Niño, Coral reefs in Sri LankaItem An Overview on Behaviors of Fishing, Fish Consumption and Preservation Techniques of Indigenous Community in Sri Lanka. With Special Reference to ‘Dambana’ Indigenous Community(Uva Wellassa University of Sri Lanka, 2021) Wijerathne, L.H.P.S.; Dias, P.C.B.; Thilakarathne, E.P.D.N.; Dias, P.G.I.; Deyshappriya, N.P.R.Indigenous communities can be identified as culturally distinct ethnic groups who are native to a particular place. The Veddas, the indigenous community of Sri Lanka are numerically small people verging on extinction (0.20%). Dambana, the most renowned original settlement of the Veddas in Sri Lanka has been arguably considered as the hub of Veddas over the past half a century. Food consumption patterns of the Veddas had been greatly altered during the recent past with the dynamic process of modernization and also with changing nature of lifestyle. An adequate and updated attention has not been paid by the existing literature on the consumption of fish along with the processing techniques of the indigenous community of Sri Lanka. Hence, this study examines the level of fish consumption and preservation methods practiced by the indigenous community in Dambana region in Sri Lanka. A structured questionnaire based interviews with the indigenous people were conducted along with Key Informant Interviews (KIIs) and a desk review to collect the required data while a descriptive analysis employed to accomplish the objectives of the study. The study observed that a higher preference on fishing (85%) compared to hunting. Previously, the indigenous community used the pots made by crushing the wild herbs, spikes made of iron and wood for fishing. Currently, several fishing gears (net gear and spears) are being adopted to increase the quantity of catching which is required for their growing consumption. Moreover, the results indicate that their fish consumption has increased approximately by 95%. Furthermore 65% of them consume fish mostly at once/twice a week. Moreover, the study examined that traditional techniques used for cooking, processing and preservation of fish (specific woods such as Cassia fistula and Manilkara hexamer) have been gradually altered and being used modern technology such as refrigerators. Additionally, preference on different fish species in the market has been enhanced (20%). Under this scenario, the study emphasizes the need of protecting traditional fishing and preservation method while facilitating in order to increase the level of fish consumption of the indigenous community through appropriate strategies. Keywords: Fishing; Fish Consumption; Indigenous community; Preservation Methods; VeddasItem A Preliminary Study on the Status of the Valithondal Coral Reef in Northern Sri Lanka(Uva Wellassa University of Sri Lanka, 2021) Narmatha, R.; Thilakarathne, E.P.D.N.; Sutharshiny, S.Coral reefs are one of the most important marine habitats in shallow tropical seas. However, there are no proper scientific records on the status of the Valithondal coral reef in Northern, Sri Lanka. Therefore, the present study was carried out to identify the abundance and diversity of Valithondal coral reef at Northern coastal waters of Sri Lanka from January 2021 to May 2021. Coral Video Transects (CVT) method was carried out for sampling at the selected location assigned by the criteria of the species abundance and water clearance where water depth less than 5m by snorkelling over 100m transect lines, which covered 10m x 100m area. Altogether 69 macro- species were recorded comprising twenty-three species of hard corals, seven species of soft corals, nine species of green seaweeds, seven species of brown seaweeds, five species of red seaweeds, thirteen species of fishes, and five species of molluscs. Species richness, Shannon-H index, and Simpson’s diversity index were 29, 3.113, and 0.9428 respectively. Comparatively, a medium diversity of coral families were recorded. Families Faviidae, Merulinidae, Acroporidae, Montastraeidae, Pocilloporidae, Leptastrea, and Poritidae are the hard corals. There is one soft corals under the family Alcyonidae. Green, brown, and red seaweed species were identified under three, two, and three families respectively. The families of the green seaweeds were Caulerpaceae, Halimedaceae, and Ulvaceae, brown seaweeds were Dictyotacea and Sargassaceae, and red seaweeds were Liagoraceae, Gracilariaceae, and Halymeniaceae. Identified fishes were included under six families; Chaetodontidae, Lutjanidae, Pomacentridae, Serranidae, Acanthuridae, and Haemulidae while molluscs are included in five families which are Buccinidae, Terebridae, Mactridae, Trochidae, and Muricidae. The highest species diversity was observed in the family Merulinidae (12.72%), Caulerpaceae (10.90%), and Alcyonidae (7.27%) and followed by Chaetodontidae (5.45%). The most abundant species were Acropora cytherea and Porites lobata in hard coral species, which is contributed to reef recovery in Sri Lanka. The other high abundant species are Lobopyton sp. and Sinularia sp. in soft coral species, Caulerpa imbricata, Caulerpa lentillifera, Caulerpa parvula, Canistrocarpus crispatus, Padina boergesenii and Halymenia durvillei in seaweed species, Chaetodontidae and Pomacentridae in fish species. The results highlighted that the high biodiversity and abundance of macro-species recorded in the Valithondal coastal waters, which would be protected by forcing effective management practices. Further studies are also needed to the sustainability of the coral reef ecosystem. Keywords: Corals; diversity indices; hard coral; macro-species; molluscs; seaweeds; soft coraItem Present Status of the Marine Aquarium Fishery in the Eastern Coast of Sri Lanka(Uva Wellassa University of Sri Lanka, 2020) Dhanasundara, I.P.T.P.; Thilakarathne, E.P.D.N.; Dias, P.C.B.; Egodauyana, K.P.U. T.; Malshani, P.K.T.Marine aquarium industry is a popular multimillionaire industry in the world and a considerable amount of global market is fulfilled by exporting from Sri Lanka since its beginning. Almost all marine ornamental species of Sri Lanka are collected from wild habitats which cause serious stock degradation of endemic and other marine species. The collection of marine ornaments has been establishing as a community-based industry on the Eastern coast of Sri Lanka due to high resource availability and accessibility compared to other regions; however, it is poorly documented. Therefore, a survey was designed to study the situation, threats, and issues of the industry on the East coast by using a questionnaire-based survey combined with field observations. Information was gathered from the collectors, suppliers, buyers, fisheries officers, and other relevant stakeholders. Almost 190 fish collectors and 15 suppliers are currently occupying during the southwestern monsoon period roughly from May to October in the Eastern coast. About 250 marine fish species (mainly butterflyfish, angelfish, damselfish, gobies, wrasses, surgeonfish, groupers, blennies & lionfish) and 50 marine invertebrate species (shrimps, Anemones, Sea Slugs & Sea lilies) are being collected mainly from Ottamavadi, Pasikudah, Kalkudah, Paul point, Adukkuparu, and Nilaweli reefs and rocky habitats. However, 01 - 05% of fish are discarding due to catching issues and 05 - 10% of caught fish are discarding due to improper handling, holding, and packing methods before reaching to local exporters. Dynamite fishing, overexploitation, fluctuations of price levels, mishandling of caught live forms, degradation of reef habitats due to natural and anthropogenic factors are the main identified threats so that the industry in the Eastern coast is certainly unsustainable. Therefore, it is highly recommended that a powerful management system should be rapidly established for the benefit of valuable marine ecosystems and the industry. Keywords: Marine ornamental fish, Reef fish, Color fish, Trincomalee, BatticaloaItem Shoreline Changes along the Western and North-Western Coast of Sri Lanka over the Past 15 Years(Uva Wellassa University of Sri Lanka, 2020) Abeykoon, K.W.H.M.R.L.C.K.; Thilakarathne, E.P.D.N.; Abeygunawardana, A.P.; Egodauyana, K.P.U.TCoastal Zone of a country is a very important interface, through which land connects the ocean. Monitoring the coastal zone of Sri Lanka is an important task in terms of sustainable development and environmental protection. As a result of natural phenomena and anthropogenic activities coastal zone is subjected to major changes. Therefore, it is necessary to identify the temporal dynamics of shoreline around the country for effective coastal zone management. Remote sensing and GIS methods can be efficiently used to determine the temporal and spatial variations of the coastal zones quantitatively and qualitatively. In this study, Google Earth satellite images have been used to analyse shoreline changes in the Western and North-Western provincial coast during the last 15 years. To estimate the accuracy of results, the ground-truthing field survey was conducted. The shorelines were delineated in Google Earth Pro 7.3 software. Tidal variation and geometric errors were considered to calculate the uncertainty to eliminate the errors in the analysis. Digital Shoreline Analysis System in ArcGIS was then used to detect the shoreline change over the period by calculating End Point Rate, Net Shoreline Movement and Shoreline Change Envelope means as the key statistics. The results show that the average erosion rates as; -1.21±0.04 m yr-1 in Kaluthara, -0.54±0.63 m yr -1 in Colombo, and -0.7±0.58 m yr-1 in Gampaha districts. However, Puttalam district shows a 0.26±0.07 m yr-1 average accretion rate while the highest accretion rate 0.95±0.58 m yr-1 shows in the Wilpattu region. 75.6% of coasts in Kaluthara and around 65% of coasts in Colombo & Gampaha have been subjected to erosion. Coasts of Puttalam have been eroded by 28.1% and accreted by 71.9%. This study revealed that the Western province coastal belt had subjected to coastal erosion than the North-Western province of Sri Lanka. Thus, identification of the dynamic nature of shoreline helps to enhance coastal zone management. Keywords: Shoreline, Remote sensing, Dynamic, Erosion, Coastal changesItem Soil Characteristics of Turtle Nesting Beaches in Southern Coast of Sri Lanka(Uva Wellassa University of Sri Lanka, 2020) Srimali, A.B.K.M.; Thilakarathne, E.P.D.N.; Abeygunawardena, A.P.; Egodauyana, K.P.U. T.; Abeygunawardena, C.J.There are seven species of marine turtles living in the world and five of them are occurring in Sri Lanka. All those five species: Green Turtle (Chelonia mydas), Olive Ridley (Lepidochelys olivacea), Hawksbill (Eretmochelys imbricata), Loggerhead (Caretta caretta) and Leatherback (Dermochelys coriacea) are nesting on Southern coastal belt of Sri Lanka and it comprises with largest marine turtle rookeries. Although, many characteristics of beaches are affecting turtle nesting; sand composition, sand porosity, vegetation cover, debris composition, soil temperature and soil pH level are considered as majors. Here eight most prominent turtle nesting beaches on the Southern coast: Yala, Bundala, Rekawa, Kalamatiya, Ussangoda, Habaraduwa, Mirissa, and Kosgoda were selected to study the sand characteristics since there is a lack of studies regarding this. The studied characteristics are sand porosity, sorting coefficient (Sφ) and mean diameter (Mn φ) and sorting level of beaches by collecting sand samples using piston core sampler up to 50cm depth level. Average sand porosities of different sites were as 28.67, 43.86, 40.77, 50.56, 30.32, 42.51, 55.23 and 21.43% while average sorting coefficient were as 0.56mm, 0.45mm, 0.60mm, 0.60mm, 0.77mm, 0.33mm, 0.95mm and 0.32mm respectively. Average mean diameters of sands of different sites were as 0.45mm, 0.34mm, 0.48mm, 0.50mm, 0.70mm, 0.24mm, 0.97mm and 0.23mm while average sorting levels were as 1.09, 0.85, 0.91, 1.02, 0.97, 0.71, 0.87 and 0.69 respectively. Among these sites, Mirissa has the highest porosity, sorting coefficient and mean diameter of sands. Yala and Kalamatiya have poorly sorted soil and other sites have moderately sorted soil. According to the literature, Kosgoda and Rekawa have the highest turtle nesting frequency. However, other characteristics of beaches and different turtle populations have to be incorporated by conducting more researches to afford strong inference on turtle nesting. Keywords: Species, Coastal characteristics, Sand, Rekawa, Turtle population of Sri LankaItem Status of the Marine Ornaments Export Industry in Sri Lanka(Uva Wellassa University of Sri Lanka, 2020) Dhanasundara, I.P.T.P.; Thilakarathne, E.P.D.N.; Dias, P.C.B.; Egodauyana, K.P.U. T.; Malshani, P. K. T.The marine aquarium industry in Sri Lanka has become a popular industry during the past few years. Exporters have shown an increasing trend for marine ornamental species exporting due to globally increased demand. Therefore, a study was designed to assess the present situation of the marine ornamental industry in Sri Lanka. Pretested questionnairebased survey with visual observations of the exporting process was conducted by selecting 30 leading marine ornaments exporting companies to assess the situation of the industry. Export data that were gathered from Sri Lanka Customs were analyzed using descriptive analysis methods. The analysis figured that approximately 611,310 marine fish individuals in 2017 and 459,425 individuals in 2018 have been exported from Sri Lanka. Thus, 151,885 individuals of prominent decrease have been observed in exporting marine ornamental fish due to the reduction of fish catch from the wild. However, a prominent growth (49,468) has been observed in exporting marine invertebrates as 105,750 individuals in 2017 and 155,218 individuals in 2018. These ornamentals have the highest demand in the USA (336,452) followed by Japan (143,497) and UK (25,386). As per the regions, the North American region had the highest demand for marine fish approximately 406,470 individuals totally in both years and followed by the North Asian region by exporting 290,916 individuals. Family Gobidae (21.6%) was the most demanded fish family in the export market followed by family Serranidae (11.7%) Acanthuridae (10.7%), and Labridae (7.7%). Most demanded invertebrate family was Hippolitidae (83.9%) followed by family Rhynchocinedae (9.0%). However, these targeting particular species in wild capture fishery may highly affect to collapse the balance of Sri Lankan reef ecosystems. Therefore, suitable strategies should be immediately implemented to fulfill the huge demand in the exporting market while sustainably utilizing natural resources. Keywords: Marine aquarium fishery, Wild catch, Reef fishItem Study of Manganese Accumulation and Temporal Variation of Water Quality in Badulu Oya(Uva Wellassa University of Sri Lanka, 2019-02) Wijesinghe, N.H.; Thilakarathne, E.P.D.N.; Guruge, K.P.G.K.P.Demand of safe drinking water is gradually increasing with rising of population in Sri Lanka as a basic need of human. Badulu oya is the main water source for drinking water in Badulla District, Uva province. Recently manganese (Mn) concentration in Demodara reservoir which was made for the purpose of water treatment facility year-round has increased unsteadily from the Sri Lankan Standards for drinking water (0.1 ppm). Therefore, the present study was conducted to determine Mn accumulation in the reservoir and to identify temporal variation of physico-chemical parameters of water. Sixteen locations from disparate upper tributaries and the reservoir were selected for sampling and that was carried out from October 2018 to December 2018. Manganese concentration of water samples were determined using Atomic Absorption Spectrometer and other water quality parameters; Turbidity, TDS, Alkalinity, Hardness were measured using standards methods. Data were statistically analyzed using SPSS 23.0 package. There was a significant difference of Mn concentration in the reservoir (06°54'47.0016" N, 081°03'38.0016" E) with the time (p<0.05) and with the location (p<0.05). Average Mn concentration in the reservoir (0.12 ppm) was significantly higher than the average Mn concentration of all other sampling sites (0.02 ppm). Average turbidity of the reservoir was correlated with average turbidity of all other sampling sites (r=0.855). Average TDS (53.25 ppm), Alkalinity (36.40 ppm), and Hardness (44.22 ppm) of reservoir were lower than the average value of all other sampling sites (60.96 ppm, 51.22 ppm, 49.77 ppm respectively). The results of this study will be helpful to take necessary actions to mitigate accumulated manganese of reservoir. Agricultural and industrial activities as mining of quarries may cause to adversely change the water quality parameters of Demodara reservoir. But more studies are needed to find out reason(s) for reservoir has higher Mn concentration.Item Study on Diversity and Abundance of Cetaceans off Mirissa, Southern Coast of Sri Lanka(Uva Wellassa University of Sri Lanka, 2019-02) Senadeera, S.K.; Thilakarathne, E.P.D.N.; Liyanage, U.S.P.K.Sri Lanka is rich with marine cetaceans (whales, dolphins and porpoises) and mainly whale watching industry has immensely developed in Mirissa, Southern coast of Sri Lanka. But up to date surveys on cetacean populations in Southern marine water is in unsatisfactory level. Hence, a shipboard survey to identify their diversity and abundance was conducted in Southern marine water off Mirissa for 48 days during August - December 2018. 5 baleen whales (suborder Mysticeti) and 8 toothed whales (suborder Odontoceti) were recorded during the survey period (13 total species). Blue whale (Balaenoptera musculus) was the most common type of baleen whale with 443 sightings in 80010´- 80046ˊ E ,05055ˊ- 05017ˊN and 1 - 3 range was their pod size. In addition to that, 60,4 and 3 sightings of Bryde’s Whales (Balaenoptera edeni), Fin whales (Balaenoptera physalus) and Ormura Whales (Balaenoptera omurai) were recorded respectively. Spinner Dolphin (Stenella longirostris) was the highest abundant toothed whale type with 2765 sightings. In addition to that, 571 of Bottlenose Dolphin (Tursiops truncatus), 125 of Stripped Dolphin (Stenella coeruleoalba), 75 of False Killer Whale (Pseudorca crassidens), 54 of Rissos Dolphin, (Grampus griseus), 30 of Pilot whale (Globicephala macrorhyncus), 7 of Killer Whale (Orcinus orca), 6 of Sperm whale (Physeter macrocephalus) and 3 of Humpback Whale (Megaptera novaeangliae) were sighted. As per whale watcher’s data, Humpback Whales were recorded in Southern coast after 2015. Since the whale watching industry in Southern coast is mainly rely on Blue whale population, they are highly vulnerable group from whale watching, shipping and fishing activities. Results provide important information on the conservation status of cetaceans. Therefore, a powerful management measure is highly needed for the conservation of cetacean populations and the sustainability of whale watching industry.