ABSTRACT
This chapter reviews the modifications used in anaerobic environments for both autotrophic and heterotrophic microorganisms. The techniques used to determine bacterial production in anaerobic environments are essentially the same as those for aerobic habitats, but the few studies carried out in the former, plus a general lack of knowledge on the metabolism of heterotrophic anaerobic bacteria, make interpretations difficult. Anaerobic water columns are the result of microbial activities. At the interfaces between oxygen-containing and oxygen-free waters, a gradient of redox conditions exists which causes the layering of microorganisms. The method commonly used for measuring primary production in all environments is based on the C-technique, introduced by Steeman-Nielsen in 1952. In anaerobic waters, primary production occurs mainly close to oxic-anoxic interfaces. Leucine and adenine incorporation and frequency of dividing cells have been used even less often than the thymidine uptake technique in anaerobic waters.
