Browsing by Author "Vijverberg, J."

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A comparative analysis on the effects of river discharge on trophic interactions in two tropical streams.
(International Review of Hydrobiology, 2017) Weliange, W.S.; Amarasinghe, U.S.; Vijverberg, J.; Leichtfried, M.; Füreder, L .
Discharge-mediated seasonal patterns of food web interactions were investigated in two streams in Sri Lanka; Eswathu Oya (a perennial wet-zone stream) and Yan Oya (a seasonal dry-zone stream). Based on volumetric proportions of diet composition, relative abundance of fish species and their daily food rations, the mean cumulative consumption of each prey taxon was estimated for each fish population. Food web diagrams were prepared using trophic index of fish, trophic class of prey and feeding interactions between fish and prey. Both streams showed seasonal patterns of discharge due to rainfall, but no significant effect was evident in the trophic index of most fish species. In both streams, cumulative consumption of prey taxa was highest during low discharge regime due to increased abundance of both prey taxa and consumers. In Eswathu Oya, diversity of prey taxa was higher during the low discharge regime, but in Yan Oya, high diversity occurred during the high discharge regime. Herbivorous and/or detritivorous fish species were rare in Eswathu Oya but dominant in Yan Oya. Complex food web structure in Yan Oya due to high fish species richness and high diversity of prey categories made it less sensitive to discharge extremes in contrast to relatively simple food web structure in Eswathu Oya. This study, therefore, highlights the importance of maintaining the quality of riparian environments for conservation of biodiversity.
Comparison of trophic structure of fish assemblages in two tropical steams in Sri Lanka: a seasonal dry zone stream and a perennial wet zone stream
(International Review of Hydrobiology, 2019) Weliange, W.S.; Amarasinghe, U.S.; Vijverberg, J.; Leichtfried, M.; Füreder, L.
Most tropical rivers especially in the Asian region, are severely impacted by various human perturbations, and the diverse habitats in streams support rich invertebrate and vertebrate communities. It is hypothesized that the fish assemblages and their dietary structure in two tropical streams differ because they flow through different terrains and are exposed to different climatic conditions. In the wet zone stream, which is geomorphological more complex, fish faunal diversity showed significant longitudinal variations, and sustains endemic fish species. In the diets of fish, taxonomic composition was different along the longitudinal gradients, but dietary taxa richness in the two streams was virtually similar having 32 dietary taxa in wet zone stream and 36 taxa in dry zone stream. In the wet zone stream, we observed a lower proportion of specialist feeding species than those in the dry zone stream. Trophic indices of individual species in fish assemblages ranging from herbivory to carnivory also indicate structuring of fish communities along the longitudinal gradients of the two streams based on dietary structure. The main differences between the fish assemblages in the wet zone compared to the dry zone were the higher number of endemic species and the lower percentage of specialist feeders with higher trophic indices. The outcome of this study hopefully contributes to plan future biodiversity conservation management schemes under various river basin development strategies.
Food web: an interactive software for quantifying Wine miller’s trophic networks in fish communities
(Sri Lanka Association for Fisheries and Aquatic Resources, 2004) Weliange, W.S.; Wickramasinghe, R.I.P.; Kumara, K.H.; de Silva, C.; Amarasinghe, U.S.; Vijverberg, J.
Observed properties of aquatic food webs have important management implications as well as important theoretical implications in the subjects of fisheries science and aquatic ecology. The food web approach is useful to understand pathways of energy and material transfer and the structure of the hierarchy of species trophic interactions in aquatic ecosystems. Winemiller (1990) presented a graphical method to investigate spatial and temporal variation in trophic networks in tropical fish communities. A computer programme was developed to produce graphic illustrations of trophic networks in the fish communities and associated food web parameters namely number of nodes, compartmentalization, connectance, average number of prey per node, average number of predators per node and ratio of consumer nodes to total nodes. The input data for this software are relative importance of food items of constituent species in the fish community and the tropic levels of prey items. The graphic illustrations and associated food web parameters mentioned above can be used for spatial and temporal comparison of trophic relationships in fish communities.
Food‐web patterns and diversity in tropical fish communities
(Journal of Lakes & Reservoirs, 2014) Amarasinghe, U.S.; Vijverberg, J.; Weliange, W.S.; Vos, M.
Promotion of sustainable capture fisheries and aquaculture in Asian reservoirs and lakes
(Hydrobiologia, Springer Netherlands, 2001) Amarasingha, U.S.; Dancun, A.; Moreau, J.; Schiemer, F.; Simon, D.; Vijverberg, J.
A collaborative international project funded by the European Union’s INCO-DC programme is undertaking limnological, fish biological, environmental and socio-economic research in five tropical lakes and reservoirs in Sri Lanka, Thailand and the Philippines over the period 1998–2001. The aim is to determine their trophic structure and their capacity to sustain both their existing fisheries and present and future aquaculture. In some cases, these activities could potentially be expanded for the benefit of rural communities and of the local market within the bounds of social and environmental sustainability. This paper describes the concepts and methods involved in this innovative multidisciplinary project which aims to integrate limnological, fisheries and socio-economic issues in a comparative approach involving Asian and European research teams.
Promotion of sustainable fisheries and aquaculture in Asian reservoirs and lakes
(Hydrobiologia, 2001) Amarasinghe, U.S.; Duncan, A.; Moreau, J.; Schiemer, F.; Simon, D.; Vijverberg, J.
A collaborative international project funded by the European Union's INCO-DC programme is undertaking limnological, fish biological, environmental and socio-economic research in five tropical lakes and reservoirs in Sri Lanka, Thailand and the Philippines over the period 1998?2001. The aim is to determine their trophic structure and their capacity to sustain both their existing fisheries and present and future aquaculture. In some cases, these activities could potentially be expanded for the benefit of rural communities and of the local market within the bounds of social and environmental sustainability. This paper describes the concepts and methods involved in this innovative multidisciplinary project which aims to integrate limnological, fisheries and socio-economic issues in a comparative approach involving Asian and European research teams.