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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 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 An evaluation of the effect of structural properties of construction materials on the brush parks fishery in the Negombo lagoon, Sri Lanka(National Aquatic Resources Research and Development Agency (NARA), Colombo 15, Sri Lanka, 2016) Gammanpila, M.; Amarasinghe, U.S.; Wijeyaratne, M.J.S.Item Trophic ecology and resource partitioning of fish assemblages in brush-parks of Negombo estuary, Sri Lanka(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Gammanpila, M.; Amarasinghe, U.S.; Wijeyaratne, M.J.S.three major brush park fishing areas (Munnakkaraya, Katunayake and Dungalpitiya) in Negombo estuary, Sri Lanka were investigated during April 2014 - April 2016 to classify diet composition, evaluate trophic guilds structure, dietary breadths, interspecific dietary overlap and to determine the degree of food resource partitioning of the community. Fraction of food (proportion by volume) consumed by species was used to establish trophic guilds, applying dietary niche breadth, and the inter-specific food niche competition among species was evaluated using Horn’s index. A cluster analysis, based on Euclidean distance resulted in six trophic guilds on the basis of feeding preferences. Although many fishes fed on a diverse range of food items, diets of 15.2% of fish species, which were included in ‘omnivore’ trophic guild, were dominated by algae/macrophytes with less amount of animal matter (omnivores), 23.9% were detritivores, 2.2% were molluscivores, 2.2% were zooplantivores, 17.4% were macro-crustacean predators and 39.1% were piscivores. The trophic levels of the constituent species varied between 1.0 and 3.0 and the both extremes were occupied by about 60% of the species in the fish assemblage. Standardized dietary niche breadth was highly variable. Species in the omnivorous feeding guild (e.g., Gerres oblongus) and those in the detritivorous feeding guild (e.g., Liza subviridis) showed higher dietary niche breadths (>0.82) showing occurrence of wide choices of food categories for them. The species of intermediate trophic class such as Carangoides talamparoides in macro-crustacean feeding guild and those which fed on macro-crustaceans and fish such as Epinephelus sp. and Lutjanus fulviflamma also had broader (>0.88) dietary breadths. The piscivores Sphyraena jello and Terapon puta with highly specialized feeding habits had the narrowest (0.0) dietary breadth. Species which primarily fed on phytoplankton/macrophytes and detritus such as Mugilids and Siganids, and species such as Acanthurus gahhm, Monodactylus argenteus, Scatophagus argus, Etroplus suratensis, Oreochromis mossambicus and Oreochromis niloticus indicated high dietary overlap ranging from 0.50 to 0.97. It was also evident that even majority of the species in the feeding guilds of macrocrustacean predators and piscivores exhibited relatively high dietary overlaps (range 0.1 - 1.0). The present study therefore illustrated that the fish assemblage in brush parks show both food resource partitioning and dietary competition, the former characterizing divergence of resource use to minimize competition for limited food resources and the latter reflecting resource abundance.Item Shedding of gill epithelia by grey mullets (Family Mugilidae) in Negombo Estuary, Sri Lanka(Sri Lanka Association for Fisheries and Aquatic Resources, 2016) Gammanpila, M.; Wijeyaratne, M.J.S.; Amarasinghe, U.S.The grey mullets (Family: Mugilidae) have been described as plankton feeders, herbivores, omnivores, slime feeders, foul feeders, bottom feeders, etc. In general, grey mullets are known to be benthic feeders. During a comprehensive trophic ecological study of fish assemblages in brush-parks in the Negombo estuary, Sri Lanka, carried out from 2014 to 2016, a food item that was not found in the aquatic environment, such as zooplankton, phytoplankton, macrophyte or detritus, was observed in the gut contents of mugilids. In this communication, the authors report that the frequency of occurrence of these peculiar items in the gut contents were shedded gill epithelia. Even though shedded gill epithelia were not considered as a food item, they were the most common item in the stomach contents contributing to 49.9% of the mean volume of stomach contents.Item Ecomorphological correlates with food habits of fish assemblages in brush parks of the Negombo estuary, Sri Lanka(Sri Lanka Association for Fisheries and Aquatic Resources, 2016) Gammanpila, M.; Amarasinghe, U.S.; Wijeyaratne, M.J.S.