Review Lecture - The chemosynthetic support of life and the microbial diversity at deep-sea hydrothermal vents

Abstract

Circulation of seawater through the upper few kilometres of oceanic crust at tectonic spreading zones results in a transformation of geothermal into chemical energy. Reduced inorganic species are emitted from warm (under 25 degrees C) and hot (under 400 degrees C) vents on the sea floor at depths of 1600 and 3000 m and are used by chemolithotrophic bacteria as terrestrial sources of energy for the primary production of organic carbon from carbon dioxide. Thus, the rich and unique animal populations found in the immediate vicinity of the vents represent ecosystems that are largely or totally independent of solar energy. They subsist by means of a food chain that is based on various microbial processes. In addition to aerobic and anaerobic bacterial chemosynthesis, a new type of symbiosis between yet undescribed chemolithotrophic prokaryotes and certain invertebrates appears to account for the major part of the total primary production at the deep-sea vent sites.