EPIPELIC BIOFILMS AS INDICATORS OF ENVIRONMENTAL CHANGES IN LOWLAND FLUVIAL SYSTEMS

GÓMEZ NORA; SIERRA MARÍA VICTORIA; COCHERO JOAQUÍN; LICURSI MAGDALENA; BAUER DELIA

Biofilms: Formation, Development and Properties

Nova Science Publishers, Inc.

Año: 2009; p. 1 - 33

The epipelic biofilm is a biologic complex of autotrophs (algae) and heterotrophs(fungi, bacteria, microinvertebrates) embedded in a polysaccharide matrix that developson the fine sediments (silt and clay) of many aquatic ecosystem worldwide of lowlandfluvial streambeds. Biofilms play a key role in the energetic balance of the fluvialsystems, contributing to the recycling of organic matter and, therefore, to their selfdepuration.The structure and function of a biofilm are affected by a variety of factors,both natural and anthropogenic, that, in turn, determine the physical and chemicalconditions of the water. The characteristics of biofilms on episammic and epilithicsubstrates have been widely described in the literature, but the features of epipelicbiofilms have been only scarcely documented. In this chapter, we present a review of theuse of the structural and functional parameters of epipelic biofilms in order to assesschanges in water and habitat quality as a result of human impact. Methodologies for thesampling and analysis of biofilms are described; and selected study cases are discussed inorder to provide information about specific composition, density, biomass, biologicalindices, primary production, respiration, and enzymatic activities of the epipelon inrelation to different uses of the surrounding land. The structural and functionalparameters of biofilms should be made an integral component in the routine assessmentof stream health as well as in the establishment of baseline values for both disturbed andundisturbed systems to be incorporated into monitoring and compliance guidelines.