http://drw.jfn.ac.lk/handle/123456789/12 2026-05-12T16:19:17Z 2026-05-12T16:19:17Z Kottage, C. D. Patrick, A. E. S. http://drw.jfn.ac.lk/handle/123456789/431 2024-07-26T13:40:58Z 2023-01-01T00:00:00Z

Hydro-climatic consequences on zooplankton diversity and abundance in perennial Vavuniya reservoir and seasonal Thandikulam reservoir in Vavuniya, Sri Lanka. Kottage, C. D.; Patrick, A. E. S. Background Zooplankton exhibit strong responses for minute changes in their habitat. Therefore, this study intended to investigate the impacts of hydro-climatic factors and related water quality variables on zooplankton abundance and diversity in the perennial Vavuniya reservoir (VR) and seasonal Thandikulam reservoir (TR), Vavuniya, Sri Lanka. Results Zooplankton diversity and abundance showed some peculiarities between seasonal and perennial reservoirs under varying hydro-climatic factors and water quality parameters during wet and dry seasons (July 2018–Febru ary 2019). There were 14 Rotifera, 4 Cladocera and 5 Copepod species in VR, and in TR, 12 Rotifera, 2 Cladocera and 5 Copepod species were identified. Although these reservoirs are located at proximity (2.48 km), the responses via zooplankton community structure toward environmental factors have been shown uniqueness to some extent. Significant negative correlation was observed for increasing NO− zooplankton diversity in perennial VR; however, only PO3− 3 (p = 0.044) and PO3− 4 (p = 0.010) concentrations with 4 concentration showed a significantly (p = 0.042) nega tive correlation in seasonal TR. Interestingly, total zooplankton abundance showed significant negative correlations with NO− 3 (p = 0.013) and PO3− 4 (p = 0.038) in perennial VR; however, insignificant negative correlation was observed in seasonal TR. Copepods make up the majority of total zooplankton abundance in both reservoirs and were signifi cantly affected by increased atmospheric temperature. Cladocera abundance in VR was highly sensitive (p = 0.032; r = − 0.856) to changes in water level. Increasing water level significantly favors the total zooplankton abundance in the seasonal reservoir but not in perennial. Conclusions Sensitivity of zooplankton community structure varies between seasonal and perennial reservoirs in different magnitudes. This is due to the increasing temperatures, increasing phosphate levels and decreasing water levels with the combination of other factors resulting in specific responses of zooplankton diversity and abundance. Therefore, it would not be surprised to use zooplankton community structure to sense the vibrant responses of differ ent freshwater habitats.

2023-01-01T00:00:00Z Samarakoon, S. N. http://drw.jfn.ac.lk/handle/123456789/429 2024-07-26T13:13:47Z 2023-01-01T00:00:00Z

Potential for aquatic cultural services in fresh water for fresh water-based ecotourism, Vawnikulam reservoir, in Mullaitivu, Sri Lanka. Samarakoon, S. N. Freshwater-based tourism comprises both tourism and an ecotourism component. The current study evaluates the diversity of freshwater fish in water resources that may suffer from freshwater-based tourism (Ecotourism) within the zone and investigates conceivable opportunities for such ecotourism in Vawnikulam major reservoir in Mullaitive district, Sri Lanka. The Mullaitive district has distinctive topographical highlights that have a high potential for fresh water resources. These highlights include three major tanks, sixteen medium tanks, and more than 100 minor tanks. There are just 21,399 land-based freshwater bodies, 8% of the total land area, and no significant perennial rivers that can be used to irrigate crops. This study used a mix of primary (qualitative and quantitative) and secondary information sources. Multi-gillnet rods and hooks were chosen as the material for the particular harvest strategy, which was utilized to gather the sample. From January to December 2022, the Vawnikulam major reservoir within the Mullaitive district was considered. Fish diversity, relative abundance, and diversity indices were determined and applied to analyze the potential for ecotourism based on freshwater resources. During the study period, 28 species including 11 families were recorded. According to national conservation status (NCS), 7 Endemic (E) species 14 Native species (NA), 6 Introduced species, and 1 species were Near threatened (NT) were identified. In order to disentangle the pathways of fresh water as aquatic cultural services and create fresh water-based ecotourism activities that can develop in Mullaitive district, Sri Lanka, this investigation distinguished the travellers within the considered area. It also analyses appropriate freshwater-based ecotourism activities.

2023-01-01T00:00:00Z Samarawickrama, R. A. D. Nanthakumaran, A. Sivakumar, P. Saravanan, S. http://drw.jfn.ac.lk/handle/123456789/426 2024-07-24T18:25:37Z 2023-01-01T00:00:00Z

Abundance and diversity of phytoplankton and zooplankton in selected village tanks in Vavuniya, Sri Lanka Samarawickrama, R. A. D.; Nanthakumaran, A.; Sivakumar, P.; Saravanan, S. The abundance and diversity of planktons in selected village tanks namely Peraru, Nochchimoddai and Mamaduwa in the Vavuniya district were studied from March to April, 2021. The objectives of the study were to identify the phyto- and zooplanktons, and to estimate their abundance and diversity in the selected village tanks. Planktons were sampled weekly using a plankton net. Based on the morphological features, samples were initially identified up to the genus level using standard keys and their respective abundance was estimated using Sedgewick- rafter counting cell. Simultaneously, water samples were also collected at each location to determine the water quality parameters such as dissolved oxygen, electrical conductivity, pH, turbidity, temperature, and, nitrate and phosphate concentrations. The results showed that there were 16 genera of Chlorophyceae, six genera of Bacillariophyceae and seven genera of Cyanophyceae, while three species of Copepods, one species of Cladocerans and 10 species of Rotifers were identified. The dominant phytoplanktons belonged to Bacillariophyceae, and represented about 50% of total population of phytoplanktons while Cyanophyceae as the least abundant. Copepods were dominant in Peraru and Nochchimoddai tanks, representing more than 50% of the total zooplankton population while Rotifers were dominant in Mamaduwa village tank, with a 58% of total zooplankton population.

2023-01-01T00:00:00Z Gajapathy, K. Saravanan, S. http://drw.jfn.ac.lk/handle/123456789/387 2022-10-26T18:17:00Z 2009-01-01T00:00:00Z

The plankton diversity and density in the Iranamadu tank in the wet season Gajapathy, K.; Saravanan, S. The Iranamadu tank is one of the largest surface aquifer found in Northern Sri Lanka. The capacity to harvest large amount of rainwater makes this reservoir a potential source for drinking water supplies. A study was conducted to determine the diversity and density of the planktons from October to December 2005, from the start till the end of the wet season in the Northern Sri Lanka. Samples were collected using Plankton nets once a week from 0500 hrs onwards along the two selected sub sampling areas (SS); one from the outlet sluice (SS I) and the other from the catchments aren (SS II). Onboard sampling was carried out too. The samples consisted of major phytoplankton like the Microcystis sp (29%), Microspora sp (26%). Chlorococcum sp (15%). Pediastrum sp (6%), Volvox sp (6%), Gleocapsa sp (6%), Nostoc sp (3%). Spirulina sp (3%). Chlamydomonas sp (3%). Sorastrum sp (2%), Spheaerocystis sp (2%) and Scenedesmus sp (2%). The zooplanktons consisted of Cyclops sp (4%), Brachiomus sp (3%). Lecane sp (3%), and a species of water mite (1%) with various density levels. The Microcystis sp was the dominant phytoplankton (1423 x10/1 at SSI and 1363 x10/1 at SS II) followed closely by Microspora sp (1288 x10/1 at SSI and 1274 10/1). The Cyclops sp (249 x10/1 at SS 1 and 229 10/1 at SS II) was the dominant zooplankton followed by the rotifers Lecane sp (152 x10/1 at SSI and 205 10/1 at SS II) and Brachionus sp (160 x10/1 at SS 1 and 187x101 at SS II). The phytoplankton density was high which indicates the need for a better filtration process in any drinking water supplying unit when this tank is considered for that purpose.

2009-01-01T00:00:00Z