Despite a long history of research, measurements of the metabolism of freshwater ecosystems have undergone many recent methodological improvements that are summarized in this chapter. After describing some relevant considerations about the dynamics of lake and streams, the recommended methods for primary production measurement are detailed. Whole-ecosystem methods of gas exchange are examined, including problems of reaeration and error estimation. An overview of chamber methods using O2 and 14C is provided, including problems of scaling up. Recent advances in microscale methods including oxygen electrodes and fluorometry are described.
