Diet and capture of Hypostomus strigaticeps (Siluriformes, Loricariidae) in a small brazilian stream: relationship with limnological aspects

Abstract

The purpose of this study is to ascertain whether variations in the limnological parameters of the Corumbataí river resulting from the discharge of a variety of wastes into its waters may be responsible for spatial shifts in the diet and capture of the armored catfish Hypostomus strigaticeps (Regan, 1907). Individuals were collected over a period of two years from two sites with similar physical, albeit distinct limnological characteristics. As a whole, the environmental variables (temperature, pH, dissolved oxygen, electrical conductivity, and total coliforms and fecal coliforms) of the two sites were found to vary significantly. The food items found in the guts of these armored catfish (sediments, diatoms, fungi hyphae, chlorophytes, cyanophytes and non-identified material) ranked differently in samples from the two sites. In the more polluted (site B), diatoms and chlorophytes ranked higher in the diet than in that of individuals caught in the more preserved location (site A). This fact may be related to the greater amount of organic material found at site B, which provides favorable environmental conditions for such algae and, consequently, for algivorous fishes. Even so, fewer fish were captured at site B than at site A, suggesting that although food is more abundant in the more polluted site, its limnological conditions appear, on the whole, to be less beneficial than the conditions at site A.Keywords: Hypostomus, Corumbataí river, environmental impact, fish, pollution. ReSumo Dieta e captura de Hypostomus strigaticeps (Siluriformes, Loricariidae) em um pequeno riacho brasileiro: relação com aspectos limnológicosO propósito deste estudo é investigar se as variações dos parâmetros limnológicos do rio Corumbataí -como uma conseqüência do lançamento de dejetos em suas águas -é responsável por variações na dieta e na captura do cascudo Hypostomus strigaticeps (Regan, 1907). Os indivíduos foram coletados durante dois anos em dois pontos do rio, com características físicas semelhantes, mas sujeitos a diferentes condições limnológicas; as variáveis ambientais (temperatura, pH, oxigênio dissolvido, condutividade elétrica, coliformes totais e coliformes fecais), quando consideradas conjuntamente, variaram significativamente entre os locais. As categorias alimentares encontradas nos tubos digestórios dos cascudos (sedimento, material não identificado, hifas de fungo, diatomáceas, clorófitas e cianófitas) apresentaram ordenamento hierárquico distinto nas amostras provenientes de diferentes pontos do rio. No local mais poluído (ponto B), diatomáceas e clorófitas ocuparam postos mais importantes em relação ao observado na dieta dos indivíduos coletados no ponto mais preservado (ponto A). Este resultado possivelmente esteja relacionado à maior concentração de matéria orgânica observada no ponto B, propiciando condições ambientais favoráveis 26 CARDONE, I. B., LIMA-JUNIOR, S. E. and GOITEIN, R.

<b>Trophic ecology of <i>Loricariichthys melanocheilus</i> Reis & Pereira, 2000 (Siluriformes: Loricariidae) in Ibicuí river, southern Brazil

“…However, although numerous studies have classified these catfishes as detritivorous, some variations in the classification of the feeding habits of several species of this family have been observed, among them E. pantherinus classified as insectivorous (Dias & Fialho, 2011), N. paranensis classified as omnivorous (Rolla, Esteves & Ávila-da-Silva, 2009), L. anus as iliophagus-omnivorous (Albrecht & Silveira, 2001). Furthermore, Cardone et al (2008) classified six species of the genus Hypostomus as iliophagus-detritivorous. Such classifications are often accompanied by some level of subjectivity because the methods for analysis of consumed foods sometimes disregard differences between microhabitats, behavior and even differences in food availability, and do not often consider ontogenetic variations (Albrecht & Silveira, 2001;Matthews, 1998).…”

“…Studies on the trophic ecology of fish of this family have been conducted in various Brazilian regions, with diverse species, including R. aspera (Soares, Hayashi, Furuya, Furuya, & Maranhão, 1997), H. strigaticeps (Cardone, Lima-Junior & Goitein, 2008), N. microps (Braga, Gomiero, & Souza, 2008), H. punctatus (Mazzoni, Rezende, & Manna, 2010), E. pantherinus and P. hystrix (Dias & Fialho, 2011), among others. Regarding the genus Loricariichthys, studies are primarily concentrated on L. anus (Albrecht & Silveira, 2001;Petry & Schulz, 2000) and L. platymetopon (Agostinho, Hahn, Gomes & Bini, 1997), but research on L. melanocheilus is lacking.…”

Feeding ecology of Hypostomus punctatus Valenciennes, 1840 (Osteichthyes, Loricariidae) in a costal stream from Southeast Brazil

“…The importance of the surrounding landscape in the diet of fish species has been recognised (Vitule et al, 2003) and it has been frequently mentioned that environmental conditions are very important to the Loricariidae species as their diet is strongly associated to the substrate and the amount of available organic matter/detritus (Casatti et al, 2005;Cardone et al, 2006). Thus, diet modification of Loricariidae species was frequently associated to altered environments as a consequence of differences in the formation of periphyton and organic matter deposition (e.g.…”

“…Thus, diet modification of Loricariidae species was frequently associated to altered environments as a consequence of differences in the formation of periphyton and organic matter deposition (e.g. Angelescu and Gneri, 1949;Dias Jr. et al, 1984;Cardone et al, 2006). Ferreira and Casatti (2006) found that detritus was the main feeding item in the diet of 3 Hypostomus species inhabiting a 1 st order stream located in a grassland area.…”

Use of food resources and resource partitioning among five syntopic species of Hypostomus (Teleostei: Loricariidae) in an Atlantic Forest river in southern Brazil

“…Although many armored catfishes normally feed on algae growing on submerged surfaces (Buck & Sazima 1995, PaGotto et al 2011, Power 1984, studies on the diet of Hypostomus indicate that they can also feed on detritus and other small food items (cardone et al 2006(cardone et al , delariva & aGoStinho 2001(cardone et al , mazzoni et al 2010. This typically benthic feeding habit has important effects on primary production, nutrient cycling and macro invertebrates drift, among other direct and indirect ecological effects (dudGeon 1993, fauSch et al 2002, mcintyre et al 2007).…”