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 ...

Proximal and mineral composition of native fish species from Amazonas, Brazil

“…Animal Sciences, v. 45, e61884, 2023 In addition, it is possible to attribute the higher levels of minerals (macro and micro minerals) in the musculature of these species to the increased diversity of food found in the flooded forests during the flood periods (Mortillaro et al, 2015;Garcez, Souza, Frutuoso, & Freitas, 2017;Silva, Arantes, Freitas, Petrere, and Ribeiro, 2020;Hurd, Baccaro, Pouilly, & Freitas, 2021). During the flood, pacu, matrinxã, curimatã, sardinha, and jaraqui are often found in flooded forests feeding mainly on fruits, seeds, insects, vegetable matter, and debris (Costa & Freitas, 2013;Mortillaro et al, 2015;Silva et al, 2020); which may explain their high Fe, Cu, Ca, and Mn values during flooding. For piramutaba, the high levels of Na and K observed during the flood season may be related to the natural history of the species, which spend a large part of their life cycle in the Amazon River estuary, in brackish waters, migrating upstream from May to October (full to low) to reproduce in the high Amazon.…”

“…It is important to mention that the Amazon is marked by a flood pulse, characterized by high waters (flood and flood peak) or low waters (dry season/drought and ebb), where the floods occur between December and June when shoals are formed, and spawning migrations occur in streams or lakes. The drought occurs from July to November when fish begin to leave flooded areas of the forest (Costa & Freitas, 2013;Arantes, Winemiller, Petrere Júnior, & Freitas, 2019). As the volume of water reduces, the fish become more vulnerable to predation and are exposed to low oxygen concentrations in water and toxic compounds (Barai et al, 2021).…”

Insights into the representativeness of biodiversity assessment in large reservoir through eDNA metabarcoding

“…However, it is also possible that the ichthyofauna habitat preferences are shaping these communities’ differences. As previously demonstrated, the ichthyofauna exhibits distinct preferences regarding water velocity and depth, for example, in lotic systems [63, 64].…”

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.…”