Carbon sources of fiin an Amazonian fl oodplain lake

Résumé fourni par la source

In a tropical fl oodplain lake in central Amazon (L. Camaleao), we investigated seasonal shifts in primary carbon sources for commercially important fi sh species over an hydrological cycle. Carbon and nitrogen stable isotope and stomach content analyses were conducted to investigate the feeding preferences of six species with different feeding habits: Cichla monoculus (piscivorous species), Schizodon fasciatus (herbivorous), Prochilodus nigricans (detritivorous), and the omnivorous species Triportheus angulatus, Colossoma macropomum and Mylossoma duriventre. Stomach content and isotopic analyses exhibited a high seasonal variation for four out of the six species. The dominant food items were fruits and seeds, plant material, zooplankton and aquatic and terrestrial insects. Over the hydrological cycle, C3 plants were the major carbon source for all fi sh species. In addi- tion, seston and aquatic C4 macrophytes were very im- portant carbon sources for most species. Our fi ndings underpin the complex trophic linkages between fl ood- plain lakes and the aquatic terrestrial transition zone as postulated by the Flood Pulse Concept.

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