Trophic structure of fish fauna along the longitudinal gradient of a first-order rural stream

Abstract

Aim: This study evaluated the trophic structure of the fish assemblage along the longitudinal gradient of a first-order rural stream. Methods Fish were sampled by electrofishing technique in December 2007, September 2008 and March 2009, at three stretch of the Itiz stream (headwater, middle and mouth). We sampled 1,255 individuals relating to 18 species. The categorization of trophic guilds was based on stomach content data of 1,096 individuals, analyzed according to the volumetric method, except for four species, which were classified according to the literature. To test the hypothesis of differences in the richness, abundance and biomass of trophic guilds along the headwater-mouth gradient, it was performed non-parametric statistical analysis of the dietary data. Was also calculated, the amplitude of trophic niche (Levins's index) for each guild. To summarize the composition and abundance of the trophic guilds along the longitudinal gradient, we applied a non-metric multidimensional scaling (NMDS). Results We registered seven guilds: herbivorous, detritivorous, aquatic insectivorous, terrestrial insectivorous, invertivorous, omnivorous and piscivorous, the latter was exclusive to headwater and middle stretches. The omnivorous guild was not recorded in the headwater. Through PERMANOVA analysis it was found that the species richness of more specialized guilds (detritivorous and insectivorous terrestrial) and of generalist invertivorous increased, while less specialized guilds like aquatic insectivorous and herbivorous, decrease significantly in headwater-mouth direction. Except by the non-expected increase of insectivorous terrestrial and decrease of herbivorous downstream, the non-metric multidimensional scaling (NMDS) identified longitudinal variations in abundance and biomass of the guilds that agree with general patterns of fish guilds distribution along environmental gradients. Conclusion These results suggest that the influence of environmental conditions around the stream (local particularities) also contributed to the formation of the observed patterns of trophic guilds along its longitudinal gradient.

Do environmental variables predict the trophic structure of fish fauna in a subtropical river (Uruguay River Ecoregion)?

“…These characteristics influence the structural complexity of habitats, and in rivers, they alter the supply and availability of resources besides influence the co-occurrence of species (Suarez et al, 2007;Carvalho and Tejerina-Garro, 2015). In this aspect, the increase in the availability of fine organic matter (like detritus; fragmented by the hydrological action and macroinvertebrates downstream) favor the detritivorous and iliophagous guilds (Nimet et al, 2015). This is especially due to the trophic specializations exhibited by species belonging to these specialist guilds.…”

“…In addition, most of these studies have been focused in rivers that were already altered by dams (Mérona et al, 2001;Loureiro-Crippa and Hahn, 2006;Luz-Agostinho et al, 2006;Delariva et al, 2013). In neotropical environments already studied, such as streams, their trophic status is largely dependent on allochthonous energy sources (Peres-Neto et al, 1995;Wolf et al, 2013;Nimet et al, 2015). In floodplain systems, which are much more influenced by flood pulses, lateral connectivity promotes nutrient and energy exchange (Goulding et al, 1988;Lowe-McConnell, 1999;Esteves et al, 2008, Leitão et al, 2017Röpke et al, 2017).…”

Ecologia Trófica De Peixes De Riacho: Uma Releitura 20 Anos Depois

“…Na região noroeste do estado de São Paulo, as teias tróficas em dois riachos basearamse principalmente em detritos, observando-se alto grau de onivoria, considerando-se um total de 139 espécies tróficas (Ceneviva-Bastos et al 2012). Em relação à segunda abordagem, diversos trabalhos têm descrito a estrutura trófica da ictiofauna de riacho considerando as variações longitudinais (Luiz et al 1998, Esteves et al 2008, Nimet et al 2015, Lopes et al 2016, Wolff et al 2013, Vieira & Tejerina-Garro 2017. Os padrões encontrados podem diferir em função do tipo de riacho, porém, de modo geral, é sabido que o gradiente produzido pela variação nos parâmetros físicos (por exemplo, vazão, largura do canal e cobertura vegetal) e bióticos contribui de forma expressiva para a formação de guildas tróficas ao longo do gradiente (Vanotte et al 1980).…”

Trophic Interactions of the Fish Communities in Cirata Reservoir, West Java

“…It will affect their trophic interactions in the use of food resources (Smith et al, 2018). The availability of food resources is a determining factor in the stability and survival of fish that will also affect the change in fish food preferences, changes in the area of the food niche and trophic interactions between fish species in the reservoir (Nimet et al, 2015). Therefore, the trophic out at eight stations, which were considered to represent the Cirata Reservoir condition (Tabel 1).…”