| | | 12.1 Introduction |
In shallow areas (<30m) sediments can support a significant fraction of the ecosystem primary production. However, at deeper sites the benthic community solely relies on the supply of organic material from the overlying water column. In coastal areas the sediments receive about 50% of the pelagic production while the fraction in the open oceans diminishes to a few percent. The major fraction of this material gets degraded through a complex web of degradation processes, while the remaining refractory material is permanently buried in the sediment. On short time scale sediments thereby acts as a source of inorganic carbon and nutrients insuring a continued production in the water column but on timescales of thousands of years sediments represent the most important sink for burial of organic material.
The organic carbon reaching the seafloor can either be consumed by macrofauna, microfauna or microbes. Typically the activity of the various organisms is coupled so that burrow linings or fecal deposits of macrofauna represent sites with stimulated microbial activity. However, in general bacteria are the main responsible for the degradation of material reaching the seafloor. The following chapter gives an introduction to the benthic microbial processes and the effects of eutrophication. For effects on fauna I refer to the previous chapter.
| | | 12.1 Introduction |