Influência do tipo de alimento e da temperatura na evacuação gástrica da piranha caju (Pygocentrus nattereri) em condições experimentais

Abstract

RESUMO: taxa de evacuação gástrica é uma variável importante para estimar o consumo diário de alimento e portanto a pressão de predação que um piscívoro exerce sobre as presas. Esta taxa pode ser influenciada pela temperatura, tamanho do predador e pelo tipo de alimento.Neste trabalho medimos experimentalmente os efeitos que estas três variáveis exercem sobre a evacuação gástrica de Pygocentrus nattererí, um dos principais piscívoros da Amazônia.Para isso foram utilizadas temperaturas variando de 27° a 31°C e os seguintes itens alimentares: músculo e nadadeira de Semaprochílodus ínsígnís e gafanhoto da espécie Paulínía sp. Estes alimentos compõem a dieta silvestre da piranha. O tamanho da piranha não influenciou na evacuação gástrica. Músculos obtiveram uma taxa de evacuação gástrica de 18,3% h -1, enquanto que nadadeira e gafanhoto obtiveram uma taxa média de 10,7% h -1. O efeito da temperatura foi mais pronunciado quando o item alimentar era músculo do que com nadadeira e insetos. PALAVRAS-CHAVE:Evacuação gástrica, peixes, Pygocentrus nattererí, temperatura, Amazônia. INFLUENCE OF FOOD TYPE AND TEMPERATURE ON GASTRIC EVACUATION OF Pygocentrus nattererí AND EXPERIMENTAL CONDITIONSABSTRACT : The gastric evacuation rate is an important variable to measure the daily ration and feeding rhythm therefore, the predation pressure of a piscivorous fish. The evacuation can be influenced by temperature, predator size and food type. In this paper it is presented experimental data of the effect of three food types in Pygocentrus nattererí, a main piscivo¬ rous amazonian fish. The temperature ranged from 27 to 31°C and three food items were used (fish muscle, fish fin rays and insect). These food items are ordinarily consumed by the piranha. Predator size had no effect on gastric evacuation. Fish muscles were evacuated at rate of 18.3% h -1, while fish fin and insect average ratio 10.7% h -1. The gastric evacuation Parts de Dissertação de Mestrado

Cloning, tissue distribution and effects of fasting on mRNA expression levels of leptin and ghrelin in red-bellied piranha (Pygocentrus nattereri)

“…The red-bellied piranha (Pygocentrus nattereri, order Characiforme, family Serrasalmidae (Fink, 1993;Kner, 1860)) is a widespread carnivorous fish species that occurs throughout rivers and lakes of South America (Behr and Signor, 2008;Silva and Araújo-Lima, 2003). In addition to being popular aquarium fish, piranhas are often sold for human consumption in local markets in the Amazon basin .…”

Influence of environmental variables and anthropogenic perturbations on stream fish assemblages, Upper Paraná River, Central Brazil

“…However, streams with riparian vegetation cover have lower water temperatures than uncovered ones (Ferreira & Casatti, 2006b), which seems to be the case of the Olhos d'água and Posse dos Rodrigues streams, where H. margaritifer and P. nasus are predominant. Generally, the influence of water temperature on fish is related to their metabolism (Silva & Araújo-Lima, 2003), which was not measured in our study. In sites lacking vegetation cover, the availability of light in the water column increases (Tejerina-Garro & Mérona, 2001).…”

HISTOLOGY AND HISTOCHEMICAL CHARACTERISATION OF THE STOMACH STRUCTURE OF THE ANTARCTIC FISH Notothenia rossii (RICHARDSON, 1844) UNDER CONDITIONS OF THERMAL STRESS

“…Temperature is a relevant environmental factor for shes in the sense that in uences nourishing rates, action of digestive enzymes, gastric and intestinal motility, secretion rate of digestive juice and intestine absorption rate (Kapoor et al, 1975;Silva & Araújo-Lima, 2003), and may lead to changes in metabolic responses. Studies on stomach histology of sh under the e ects of thermal stress are missing, but studies with mammals indicate that alterations in mucous layers may, in the long term, compromise gastric evacuation, which, in turn, tends to lead to increased acidic concentration inside the stomach and, consequently, gastric ulcers (Meyer, 1999).…”

“…Temperature directly or indirectly affects living organisms, determining metabolic rate and the development of digestive chemical reactions and metabolic processes (Kapoor et al, 1975;Ba-Omar & Victor, 2000;Silva & Araújo-Lima, 2003;Kawaguchi, 2007;Handeland, 2008) and increases susceptibility to histopathology in some chronic cases. Nevertheless, there are few studies focused on the morpho-histology (Freiberger, 1996) and functional aspects of the digestive system of Antarctic shes subjected to thermal stress (Hernandez-Blazquez et al, 2006).…”