"Isótopos estáveis de C e de N como indicadores qualitativo e quantitativo da dieta do tambaqui (Colossoma macropomum) da Amazônia Central" / Stable isotopes C and N as indicators of qualitative and quantitative dietary variations of tambaqui (Colossoma rnacropornum) in Central Amazoniam

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

The flooded areas of white-water rivers of the Amazon Basin –“ várzeas” - are responsible for more than 90% of the total capture fisheries in the region, The annual flooding cycle elicits qualitative and quantitative variations of fish natural diet, with direct influence nutritional condition of several fish species, such as the tambaqui (Colossoma macroporum), an economically important amazonian food fish which dwells in the “várzea” , and has presented decreasing capture potential over the last decade This work aims to determine how the hydrological cycle influences, both quantitatively and qualitatively, alimentary seasonality of the main energy sources for tambaqui at: lake Camaleão, Central Amazon, through the analysis of stomach contents and isotopic composition of food items, and the incorporation dynamics of alimentary carbon and nitrogen in different fish tissues, Stomach repletion degree and relative importance of the alimentary items varied with the water level, while stable C and N isotopes showed the relative dietary importance of either C3 or C4 photosynthetic- pathway plants, and their accompanying macro fauna for tambaqui, and the zooplankton, the main supplier of N to the species, The pattern of incorporation of alimentary C anci N in tambaqui diflereci for C, anci C4 clieis. Differences m the nutritional values of diets and the growth rate influenced the incorporation dynamics of C and N, The velocity of substitution of alimentary C and N was directly related to the quality of the source and to the functionality of the body tissue, The minimum time for substitution of 99% of the isotopic sign of the C3 diet in muscle tissue of fingerling tambaqui was 85 days. The combination of the two analysis methodologies revealed how complex are the feeding habit: and alimentary behavior of the tambaqui, and how much it depends on the flood pulse. Both the intervention in the hydrological cycle of the Amazonian rivers and the alteration in the landscape of their “várzeas”, can be disastrous for the survival of the species.

ASSUNTO(S)

dieta animal animal dietary carbono peixes tropicais tropical fishes nitrogen carbon nitrogenio

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