ABSTRACT
In this chapter, we describe the main mechanisms and processes involved in the fl ow of energy in freshwater ecosystems. The chapter presents the main methods and approaches used to measure the primary productivity of photosynthetic autotrophs, photosynthetic bacteria and the factors involved in primary production. Information and data on heterotrophic bacterioplankton and their productivity are also presented, as well as the principal techniques and processes for measuring secondary production in aquatic systems, including data on secondary production in several different ecosystems.
