Dinâmica alimentar de Rhaphiodon vulpinus Agassiz, 1829 (Teleostei, Cynodontidae) no alto Rio Tocantins (GO) em relação ao represamento pela UHE Serra da Mesa

Abstract

Abstract:The diet and feeding activity of Rhaphiodon vulpinus were studied before and after the impoundment of the upper Tocantins river by the Serra da Mesa hydroelectric plant (Goiás State, central Brazil), in two areas: reservoir and downstream. Stomach contents of 214 specimens were analyzed: 46 from the river phase (Dec./95 to Oct./96), 100 from the filling phase (Dec./96 to Apr./98) and 68 from the operation phase (Jun./98 to Feb./00). The species was confirmed as a piscivore, with occasional consumption of insects and vegetal material. In the downstream area, none of the identified prey was common to all the three phases. The most consumed prey were Geophagus cf. surinamensis, Hemiodus ternetzi and Pimelodus blochii during the river, filling and operation phases, respectively. The engraulid Anchoviella sp. was exclusive to the operation phase. Prey richness was higher in the reservoir. Small-sized characids were consumed during the three phases, whereas H. ternetzi, Leporinus friderici and Tetragonopterus argenteus were exclusive to the river phase, Ctenobrycon hauxwellianus and Pimelodidae to the filling phase, and Satanoperca aff. jurupari to the operation phase, the latter being the most important in this phase. The feeding activity, given by the proportion of stomachs with food (EcA%) and empty (EV%), increased in each phase in the downstream area. In the reservoir, the opposite pattern was observed. No correlation was found between the sizes of predator and its prey; however, larger predators consumed prey of a wide size range. Keywords: piscivory, Cynodontidae, reservoir, feeding, Tocantins-Araguaia Basin. PACHECO, A.C.G., BARTOLETTE, R., CALUCA, J.F., CASTRO, A.L.M., ALBRECHT, M.P. & CARAMASCHI, E.P. Dinâmica alimentar de Rhaphiodon vulpinus Agassiz, 1829 (Teleostei, Cynodontidae) no alto Rio Tocantins (GO) em relação ao represamento pela UHE Serra da Mesa. Biota Neotrop. 9(3): http://www.biotaneotropica.org.br/v9n3/pt/abstract?article+bn01009032009. Resumo:A dieta e atividade alimentar de Rhaphiodon vulpinus foram estudadas antes e após o represamento do alto Rio Tocantins pela UHE Serra da Mesa, GO, em duas grandes áreas: reservatório e jusante. O conteúdo estomacal de 214 exemplares foi analisado, sendo 46 da fase rio (dez./95 a out./96), 100 da fase enchimento (dez./96 a abr./98) e 68 da fase operação (jun./98 a fev./00). A espécie confirmou-se como piscívora, com consumo eventual de insetos e material vegetal. Na área a jusante, dentre os peixes-presa identificados, nenhum foi comum às três fases. As presas mais importantes foram Geophagus cf. surinamensis, Hemiodus ternetzi e Pimelodus blochii nas fases rio, enchimento e operação, respectivamente. Anchoviella sp. foi exclusiva da fase operação. Já no reservatório, a riqueza de presas foi maior. Caracídeos de pequeno porte foram consumidos nas três fases, ao passo que H. ternetzi, Leporinus friderici e Tetragonopterus argenteus foram exclusivas da fase rio, Ctenobrycon hauxwellianus e Pimelodidae, da fase enchimento, e Satanoperca aff. jurupar...

Diet composition and food overlap of Acestrorhynchus britskii and A. lacustris (Characiformes: Acestrorhynchidae) from Sobradinho reservoir, São Francisco river, Bahia State

“…The fact that the ingested species were relatively large, with high nutritional value and easily digestible reduces the time spent until satiation (HAHN et al, 1999), leading the individual to feed less frequently. This trait greatly hinders the study of piscivore diets, due not only to the high incidence of empty stomachs but also by the high level of digestion of prey (PACHECO et al, 2009). Bennemann et al (2000) obtained only 23.6% of stomachs containing food in 203 analyzed specimens of A. lacustris.…”

Biology of non-native species (Rhaphiodon vulpinus Agassiz, 1829) (Characiformes, Cynodontidae) in a cage fish farm area, Upper Paraná River Basin, Brazil

“…However, the high abundance of shrimp recorded in diet indicates an opportunistic trait, suggesting dietary flexibility based on the preferential resources available in the environment (Abelha et al, 2001), a food tactic typical of opportunistic piscivorous species (Kahilainen & Lehtonen, 2003). In addition, the presence of vegetation as an item consumed in the CT area is possibly attributed to the stomach contents of the prey (in this case, fish) or accidental consumption by prey living in the marginal vegetation (Pacheco et al, 2009).…”

“…It is not uncommon to find a high incidence of empty stomachs among this species, as its prey is relatively large, high nutritional value and easily digestible, reducing the time needed to reach satiety (Pacheco et al, 2009;Ferriz et al, 2016). This characteristic makes it difficult to study the diet of piscivorous species, not only due to the incidence of discharge of empty stomachs but also the rapid digestion of prey (Hahn et al, 1999;Pacheco et al, 2009). In addition, the lower presence of stomachs with contents in the CT area may be the result of the higher percentage of shrimp consumed in this area.…”

Effects of river damming in Neotropical piscivorous and omnivorous fish: feeding, body condition and abundances

“…Such methodology has been used by several authors to describe the impacts of reservoir formation in fish assemblages (Gubiani et al, 2009;Pacheco et al, 2009;Abelha et al, 2012;Orsi & Britton, 2014). The condition factor expresses individual wellbeing with respect to the environment and it compensates for changes in the form or condition with length (Le Cren, 1951).…”