Microbial Communities (Biotic Class)

Component: Biotic

Unique Identifier: 392

Biotic Setting	Benthic/Attached Biota
Biotic Class	Microbial Communities
Biotic Subclass	Structure Forming Microbes Mat/Film Forming Microbes

Description

Definition

Areas dominated by colonies of microscopic or single-celled organisms that form a hard structure, visible film, layer, or mat on or near the surface of the substrate. Colonies may be composed of benthic microalgae (e.g., diatoms), photosynthetic bacteria (e.g., cyanobacteria), archaea, saprotrophic bacteria (e.g., decomposers or decay organisms), chemoautotrophic bacteria, or other microbial groups. These features may exist on or near the surface of the sediment either subtidally or subaerially (Figure 8.12), or they may exist as extensive areas of decay associated with dead organisms that have fallen to the seafloor (Figure 8.13).

Note: There may be high levels of biotic diversity within microbial mats. Microbial mats are often encountered in extreme environments where grazing pressure from multi-cellular organisms is reduced; for example, they can be observed in the high intertidal zone, in areas of low dissolved oxygen, and in deep-sea areas around thermal vents.