Papel da alça microbiana na dinâmica trófica de um lago de várzea na Amazônia Central

Pedro Caraballo

During the hydrologic year of 2007-2008, the lago Catalão, a floodplain lake which is influenced by two of the worlds largest rivers (Solimões and Negro), was studied in terms of the dynamic of water column and the trophic dynamic of the microbial food web. At the beginning of the flood the lago Catalão is influenced by the rio Negro and at the end of this period and during the flooded by the Solimões. This hydrologic condition characterize the lake as being of mixed waters. The water column was monitored monthly every meter until the bottom in periods of 24 hours, in terms of electric conductivity, water temperature and dissolved oxygen, with the intention of having abiotic information for the analyses of the biological data. The lake presented strong thermal stratification during the water level increase and diminish periods, and instability in the dry and flooded period. During the dry season the mixture of the water column occurs by the force of the wind and during the flood by the simultaneous effect of wind and low temperature, which is called as "friagen", a climatological phenomenon of continental character, that induces an inversion of the water column in the Amazon lakes. In biological terms, the isotopic values of δ13C and δ15N from phytoplankton, zooplankton, fish larvae, insects and detritus was studied in the littoral, pelagic and aquatic macrophytes regions. A general vision of the components from the microbial food web was used to determine the role of the heterotrophic bacteria in the lakes carbon flow. The results suggest a low participation of the microbial loop in the flow of carbon to the higher trophic levels.

Papel da alça microbiana na dinâmica trófica de um lago de várzea na Amazônia Central

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