Aquatic macrophyte decomposition: enzymatic action over lignocellulosic detritus

Abstract

The breakdown of detritus by microorganisms, in aquatic environments, through enzymatic activities represents the key process in the regulation of the organic matter and nutrient cycling. In this context, this research approaches the action of extracellular enzymes in the dynamics of the decomposition of three species of aquatic macrophytes (Salvinia auriculata, Eichhornia azurea and Cyperus giganteus), in an oxbow lagoon of the Mogi-Guaçu river, the Óleo lagoon. The decomposition processes is represented by mass loss of the three species, being the enzymatic activities of the microorganisms that act over the detritus measure from the litter bags. The activities of five enzymes will be described: celullase, peroxidase, xilanase, phenol oxidase and glycosidase, that operate, in set, during the degradation of aquatic macrophytes. The development of models that consider of the enzymatic decomposition and the kinetic depends on the establishment of relations between the enzymatic activities and the rates of mass loss. When establishing such relations, it is possible to estimate the instantaneous rates of mass loss in situ. There are the need of establish connections between the environmental reactions at the molecular level and factors that conditioned the decomposition, generating basic information on heterotrophic potential of ecosystems. This study, also it will evaluate the mechanisms that control the transformations of the detritus in situ. It is important to stand out, the pioneering character of this study in tropical environments; as well, the scarcity of results of this nature in the studies applied to aquatic ecosystems. (AU)