Food‐web patterns and diversity in tropical fish communities

Abstract

We compared the food webs of three Sri Lankan reservoirs: Minneriya (ancient and shallow; Udawalawe (young and shallow) and Victoria (young and deep). Species richness of the fish community was highest in Minneriya (30 species), intermediate in Udawalawe (21 species) and lowest in Victoria (18 species). Fish species belonged to 11 families, with Cyprinidae dominating the community both in terms of abundance and species richness. We used the daily amount of food consumed per fish species to distinguish weak from strong trophic interactions in these food webs. The fish community consumption pattern was characterized by a few strong interactions and many weak ones. The number of major consumers (contributing > 5% of the total fish community consumption) in each reservoir was small and similar for the three reservoirs. Puntius filamentosus 1 and Amblypharyngodon melettinus were the two major consumers in all three food webs. Puntius chola was a major consumer in Minneriya andVictoria, but not in Udawalawe, where it was feeding less on detritus than in the other two food webs. In all three reservoirs was the fish community mainly feeding at the bottom of the food web, on algae, macrophytes and detritus, with very little piscivory taking place. Average food web length was measured as the mean trophic index weighted for the consumption rates of the various fish populations which together compose the fish community. In comparison with most other tropical lake/reservoir food webs in Asia and Africa, of which data were available, was the average food web length in the Sri Lankan reservoirs relatively short. Furthermore, traditionally unexploited species, as opposed to species of commercial fisheries interest, Oreochromis mossambicus and O. niloticus, are major role players in trophic dynamics of reservoir ecosystems. As such, the potential of their exploitations should be considered in the management of reservoir fisheries.

A comparative analysis on the effects of river discharge on trophic interactions in two tropical streams

“…In the present study, a simple approach was used that could be applied for comparative studies of trophic dynamics in aquatic habitats. Amarasinghe et al () presented a similar approach for comparative assessment of trophic status in three Sri Lankan reservoirs. This approach, due to its simplicity, is useful for environmental assessment to investigate the impact of change of flow regimes in development efforts involving alternation of hydrology in stream environments.…”

“…In Sri Lankan reservoirs, various aspects such as food resource partitioning among fish (Weliange & Amarasinghe, ), seasonality and ontogeny of dietary habits of fish (Weliange & Amarasinghe, ), trophic patterns of fish (Weliange, Amarasinghe, Kakkaeo, et al, ), diel feeding periodicity, daily ration and relative food consumption of fish (Weliange, Amarasinghe, Moreau, & Villanueva, ), ecomorphological patterns of fish (Weliange, Amarasinghe, & Schiemer, ), food consumption of fish (Amarasinghe, Weliange, Kakkaeo, Villanueva, & Moreau, ) and food webs (Amarasinghe, Vijverberg, Weliange, & Vos, ; Villanueva, Moreau, Amarasinghe, & Schiemer, ) have been studied. However, studies on stream ecology in Sri Lanka are restricted to hydrobiological surveys (Geisler, ), food and feeding habits of stream fish species (Costa & Fernando, ), and niche segregation within stream fish communities in the wet zone (De Silva, Cumaranatunga, & De Silva, ; Moyle & Senanayake, ; Wikramanayake & Moyle, ).…”

Effectiveness of carp seed stocking in large reservoir ecosystems of India

“…The trophic level (TL), fishery status, feeding habit and conservation status have also been tabulated (Froese & Pauly, 2021; IUCN, 2021). The “TL” is often defined in different ways in the literature (Amarasinghe et al, 2014; Pauly & Palomares, 2006; Winemiller, 1990). The TLs taken from FishBase (Froese & Pauly, 2021) for the present study were based on Palomares et al (1993), Pauly and Christensen (1995), Pauly and Palomares (2006) and which were discussed in detail by Amarasinghe et al (2014).…”

“…The “TL” is often defined in different ways in the literature (Amarasinghe et al, 2014; Pauly & Palomares, 2006; Winemiller, 1990). The TLs taken from FishBase (Froese & Pauly, 2021) for the present study were based on Palomares et al (1993), Pauly and Christensen (1995), Pauly and Palomares (2006) and which were discussed in detail by Amarasinghe et al (2014). In ECO‐PATH model (Pauly & Palomares, 2006) TL is defined as follows: where TROPH j is the fractional TL of prey ( j ); DC ij is the fraction of j in the diet of i ; and G is the the total number of prey species.…”

Potential for aquatic cultural services in fresh water for fresh water- based ecotourism, Vawnikulam reservoir, in Mullaitivu, Sri Lanka

“…Relative abundance = (ai/A) 100 % ……………………………………………………… (1) Where, ai = the number of individuals caught In the i th species A = the total number of individuals…”