Trophic ecology of the ichthyofauna of a stretch of the Urucu River (Coari, Amazonas, Brazil)

Abstract

Introduction: The floodplains of the large Amazonian rivers are very productive as a result of seasonal fluctuations of water levels. This favors the fishes as they are provided with a wide range of habitats and food resources; Aim: In this study, we identified the trophic structure of fish assemblages in the upper river Urucu area (State of Amazonas -Brazil), observing seasonal changes determined by the hydrological cycle; Methods: Samples were collected with the aid of gillnets, during the flood season (April/2008) and the dry season (August/2008) in areas upstream and downstream of ports of the Urucu river within the municipality of Coari, Amazonas, Brazil; Results: 902 individuals of seven orders, 23 families and 82 species were collected. Fishes were more abundant in the dry season than in the flood season, and the piscivores and carnivores (Serrasalumus rhombeus and Osteoglossum bicirrhosum) were the most significant trophic categories in the dry season whereas piscivores and insectivores (Serrasalumus rhombeus, Bryconops alburnoides and Dianema urostriatum) were more abundant in the flood season. The trophic diversity, dominance and evenness were very similar in all sampling periods and show lower values than taxonomic index patterns, except for the trophic dominance in the dry season. Taxonomic diversity and dominance were higher in the flood season if compared to the dry season, but figures were quite uniform and there were no great discrepancies between seasons. Conclusion: We found through our studies that the dry and flood seasons work as regulatory factors of abundance of fishes of certain trophic categories in the Urucu river, what can be possibly explained by the availability of resources and the food spectrum of each category. Resumo: Introdução:As áreas inundáveis dos grandes rios amazônicos são muito produtivas, como resultado das flutuações sazonais no nível da água, favorecendo os peixes que passam a dispor de um amplo espectro de habitats e recursos alimentares; Objetivos: Neste estudo, identificamos a estrutura trófica das assembléias de peixes do curso superior do rio Urucu (Amazonas -Brasil), observando mudanças sazonais determinadas pelo ciclo hidrológico; Métodos: As coletas foram realizadas com auxilio de baterias de malhadeiras, no período de cheia (abril/2008) e seca (agosto/2008), em áreas a montante e jusante de portos localizados no rio Urucu, no município de Coari, Amazonas, Brasil; Resultados: Foram coletados 902 indivíduos compreendidos em sete ordens, 23 famílias e 82 espécies, a abundância de peixes no período da seca foi superior ao período da cheia. Piscívoros, onívoros e carnívoros foram as categorias com abundância mais elevada na seca; sendo essas mesmas categorias, incluso o grupo dos detritívoros, mais abundantes na cheia. Bryconops alburnoides, Dianema urostriatum e Serrasalumus rhombeus foram as mais abundantes no período da cheia e Osteoglossum bicirrhosum, Serrasalumus rhombeus e no período da seca; Conclusão: Constatamos através de nossos estudos a importância dos ...

High waterborne Mg does not attenuate the toxic effects of Fe, Mn, and Ba on Na+ regulation of Amazonian armored catfish tamoatá (Hoplosternum litoralle)

“…The Urucu river and its tributaries are Bblack water^environments, which are recognized as acidic ion-poor waters (see Sioli 1984;Cunha and Pascoaloto 2009 for more details on the ionic composition and physico-chemical properties of Bblack waterr ivers). A very rich local ichthyofauna is commonly found in these black water rivers (Costa and Freitas 2013) that evolved at this unusual conditions, displaying singular adjustments in ion regulation mechanism, particularly those related to Na + and Cl − homeostasis, to cope with the low waterborne ionic levels (Gonzalez et al 2005). Thus, in a scenario of formation water leakage, the raise in levels of major cations and metals might disrupt the osmoregulatory balance of fish, having deleterious consequences for the organisms and affecting their fitness and survival, which might negatively impact the whole local biodiversity.…”

Trophic ecology of speckled peacock bass Cichla temensis Humboldt 1821 in the middle Negro River, Amazon, Brazil

“…Studies on the trophic ecology of fish can help to understand the trophic organisation of the aquatic ecosystem, providing information about the energy flow, availability of food items, diet and feeding behaviour of the species (Costa & Freitas, 2013;Prudente, Carneiro-Marinho, Valente, & Montag, 2016). Stomach content analysis (SCA) is a common method for dietary analysis.…”