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Item Dietary Guild Structure in Fish Assemblages and Trophic Position of Constituent Species in Brush Parks of a Tropical Estuary(Asian Fisheries Society, 2019) Gammanpila, M.; Amarasinghe, U.S.; Wijeyaratne, M.J.S.Trophic guild structure and dietary niche breadth in tropical fish communities are important to identify functional groups and to understand how trophic positions of constituent species help coexistence. Objective of the present study was to investigate whether the constituent species of fish assemblages in brush parks could be grouped into trophic guilds and how these species contribute to structure the fish community along trophic dimensions. Diets of 46 fish species caught in brush parks were analysed and the food items were categorised into 11 broad groups. Based on the composition of diets, fish were grouped into 8 trophic guilds. Levin’s index of niche breadth indicated that the constituent species in the trophic guilds for which food was abundant, were generalists, whereas the trophic guilds of higher trophic levels were specialists. Within each trophic guild, constituent species showed different trophic indices indicating low inter-specific competition resulting in optimum food resource utilisation.Item Life history patterns of some selected endemic freshwater fish species inhabiting two major river basins of Sri Lanka(Sri Lanka J. Aquat. Sci. 23(1) (2018): 77-84, 2018) Shirantha, R.R.A.R.; Wijeyaratne, M.J.S.; Amarasinghe, U.S.Life history information on six endemic fish species namely Belontia signata, Pethiya cumingii, P. nigrofasciata, Puntius titteya, Rasboroides vaterifloris and Garra ceylonensis inhabiting the Kalu Ganga and Kelani Ganga river basins in Sri Lanka was evaluated. The growth constant of the fish species showed a positive relationship with the river order where they inhabited. The length at 50% maturity (Lm) significantly correlated with the asymptotic length and growth constant indicating that fishes with slow growth become sexually mature late in their life cycles. The optimal lengths for sustainable exploitation of the fish species studied were significantly (p<0.01) correlated with asymptotic lengths and lengths at 50% maturity whereas negatively correlated with natural mortality. This analysis indicated that Lm was a foremost function of size of fish apart from maximum length observed (Lmax,) and that Lm and Lmax can be used as deterministic variables for quantifying optimal size of exploitation for sustainability and conservation of fish populations.Item Morphological correlates with diet of fish assemblages in brush park fisheries of tropical estuaries.(Environmental Biology of Fishes., 2017) Gammanpila, M.; Amarasinghe, U.S.; Wijeyaratne, M.J.S.Brush park fishery in Negombo estuary, Sri Lanka is a traditional fishing practice which relies on fishes attracted to artificial woody fish aggregation devices. This study investigates whether constituent species in these brush parks exhibit morphological variations in relation to their dietary habits. Fishes caught in brush parks were sampled from April 2014 to April 2016 covering rainy, intermediate and dry seasons. There were 817 specimens of 46 species belonging to 24 families. From each specimen, 17 morphological attributes were determined and diet composition of each species was analyzed in terms of relative biovolume. Trophic index of each species estimated from the proportions of dietary items and their possible trophic level in the community was significantly related to two body proportions (Maximum body height/Maximum body width and Total length/ Maximum body height) which described shape of fish. Principal component analysis of morphometric attributes and dietary habits indicated that the species in the higher trophic levels are characterized by slender, long-body shapes and those occupy lower trophic levels are predominantly laterally compressed with deep body shapes. As such, structure of coexisting species in brush parks of Negombo estuary is predominantly along the trophic dimension and is related to morphological traits of constituent species. The predictive power of ecomorphological correlates with diets of fish species other than mugilids which are attracted to brush parks, can therefore be considered as a useful tool for conducting rapid ecological assessment.Item Morphological correlates with diet of fish assemblages in brush park fisheries of tropical estuaries(Springer Netherlands., 2017) Gammanpila, M.; Amarasingha, U.S.; Wijeyaratne, M.J.S.Brush park fishery in Negombo estuary, Sri Lanka is a traditional fishing practice which relies on fishes attracted to artificial woody fish aggregation devices. This study investigates whether constituent species in these brush parks exhibit morphological variations in relation to their dietary habits. Fishes caught in brush parks were sampled from April 2014 to April 2016 covering rainy, intermediate and dry seasons. There were 817 specimens of 46 species belonging to 24 families. From each specimen, 17 morphological attributes were determined and diet composition of each species was analyzed in terms of relative biovolume. Trophic index of each species estimated from the proportions of dietary items and their possible trophic level in the community was significantly related to two body proportions (Maximum body height/Maximum body width and Total length/ Maximum body height) which described shape of fish. Principal component analysis of morphometric attributes and dietary habits indicated that the species in the higher trophic levels are characterized by slender, long-body shapes and those occupy lower trophic levels are predominantly laterally compressed with deep body shapes. As such, structure of coexisting species in brush parks of Negombo estuary is predominantly along the trophic dimension and is related to morphological traits of constituent species. The predictive power of ecomorphological correlates with diets of fish species other than mugilids which are attracted to brush parks, can therefore be considered as a useful tool for conducting rapid ecological assessment.Item Studies on the biology of young grey mullet, Mugil cephalus L.(FAO of United Nations, Rome, Italy, 1976) de Silva, S.S.; Wijeyaratne, M.J.S.Item Change detection in the channel segment of Negombo Estuary, Sri Lanka using time series satellite data and its possible impacts on estuarine productivity(The Asian Fisheries Society, 2011) Dahanayaka, D.D.G.L.; Tonooka, H.; Wijeyaratne, M.J.S.; Minato, A.; Ozawa, S.Item Trophic condition of Madu Ganga Estuary, a Ramsar Wetland in Sri Lanka(2017) Silva, T.M.S.D.G.; Wijeyaratne, M.J.S.Madu Ganga Estuary, which extends for 915 ha is a Ramsar wetland in the south- western coastal region of Sri Lanka. This slow flowing water body is rich in biodiversity with 248 vertebrate species which include 20 endemics and 303 plant species. About 10% of the 111 species of birds are winter migrants. Cinnamon and paddy cultivations form the dominant land use type in the surrounding area and at present, a nature based tourism industry is also developing rapidly at the estuary due to its ecological and aesthetic significance. In addition, resident traditional fishermen are involved in commercial fishing activities using traditional gear such as Kraals. The present study aimed to figure out the trophic condition of this important wetland. During the study period from March to November 2014, the mean values for physicochemical parameters were found to be as follows; Depth: 1.89 m; Secchi Depth (SD): 0.91 m; Temperature: 30.8 ˚C; Total Dissolved Solids (TDS): 8.8 g/L; Salinity: 8.29 g/L; pH: 7.2; Dissolved Oxygen (DO): 6.79 mg/L; Biological Oxygen Demand (BOD 5 ): 1.40 mg/L; Nitrate-N: 0.2 mg/L; Total dissolved phosphorous: 0.09 mg/L and Total Phosphorous (TP): 0.17 mg/L. The TP values suggest that the trophic condition of this highly ecologically and economically important wetland is eutrophic. Excess and indiscriminate use of fertilizer in the watershed area and soil erosion appear to be the major reasons for this condition, which may be controlled by educating farmers on repercussions of applying excess amounts of fertilizer and ensuring that only the recommended levels are applied. Remote Sensing methods can also be used in nearby agricultural fields to detect the areas where deficiency symptoms are present and fertilizer can be applied only to those regions. In addition, erosion control methods can also be applied to retain the fertilizer within the agricultural fields without being washed into the estuary with storm water.Item Prosperity Challenge is in Your Hands(South Eastern University of Sri Lanka, 2017) Wijeyaratne, M.J.S.Item University research towards sustainable development(University of Ruhuna, 2016) Wijeyaratne, M.J.S.Item Branding, Advertising and Sustainable Development(2017) Wijeyaratne, M.J.S.