ABSTRACT
Despite algae being diverse organisms inhabiting marine, estuarine, and freshwater habitats and having sizes from few micrometers to several meters, this chapter will focus on freshwater microalgae, especially phytoplankton and microphytobenthos. In freshwater ecosystems, microalgae from phytoplankton and microphytobenthos are by far the most important and widely used for the evaluation of water quality than macroalgae. Figure 7.1 shows a classication of planktonic organisms according to their size, taxonomic group, and metabolism. This classication can also be adapted to benthic organisms.
