Biofilms thrive in a wide range of both natural and man-made environments, the only limiting factor being the presence of adequate water (Sutherland, 2001). They are found in aquatic and soil environments, on plants, pipes and filtration systems and even on the tissues of animals and humans (Bradding et al., 1995; Wingender et al., 1999; Flemming & Wingender, 2001; Sutherland, 2001). At the simplest level, biofilms can be considered as communities of microorganisms attached to a surface (O’Toole et al., 2000). Depending on their location, they are given different names. In river, lake and estuarine environments, the “periphyton” (or periphytic biofilm) groups all biofilms growing in the vicinity of macrophytes, including the “epiphyton” (or epiphytic biofilm) attached to the stems and leaves of macrophytes. Biofilms on the bed are generally sub-divided based on the kind of substrate they are attached to, for instance, the “epilithon” or epilithic biofilm grows on the sediment whereas the “epixylon” or epixylic biofilm grows on wood. However, other names can be found in the literature, for example, “sediment biofilms” for growth on fine-grained (<2 mm diameter) bed sediments (i.e. on clays, silts or sands) and “microphytobenthos” for photosynthetically active (autotrophic) biofilms growing on marine mudflats.