Appreciation of scalar influences on headwater benthic diatom communities and the impact of, often interacting, multiple pressures on these communities is important for advancing ecological understanding of these communities. It also has the following on objective of allowing for more accurate representation and interruption of biological monitoring efforts. My project aims to investigate the role of benthic diatom assemblages as measures of productivity in stream environments, it relation to benthic diatom assemblage composition and how it varies over space and time according to specific physical, chemical and biological variables.