Alteration of Microbial Metabolic Activities in Association with Detritus

Detritus serves as a microhabitat, or microzone, hosting redox gradients, altered microbial metabolism and associated biochemical nutrient transformation processes qualitatively and quantitatively distinct from the ambient planktonic environment. Through the application of tetrazolium redox indicator salts, microautoradiography and microelectrode analyses, it has been shown that distributions of microbial communities and their extracellular deposition products on detrital as well as non-detrital submersed surfaces are patchy in nature, both in terms of physical distribution and associated metabolism. This patchiness promotes the development of steep redox gradients, which in tum lead to diverse microhabitats in which microorganisms, protozoans and invertebrates, all having narrow environmental tolerances, can reside. The compact nature of gradients helps promote diffusive exchange of metabolites, gases and nutrients, thereby maintaining community diversity and structural stability of microzones. Microzones also harbor specific nutrient transformation processes (i.e., nitrogen cycle N₂ fixation, ammonification, nitrification and denitrification) which may otherwise be unfavorable or inhibited in ambient waters.

The promotion, regulation and maintenance of specific nutrient transformation reactions in microzones are all implicated in determining nutrient availability and trophic states of affected aquatic systems.