ABSTRACT
Marine hydrothermal vents are extreme environments in the ocean where tectonic activities are evidenced in the plate boundaries or mid-ocean ridges. Hot mineral-rich water coming out through the hydrothermal vent crevices supports various life forms. Although these conditions are not favorable for most of the living organisms, microorganisms are well adapted to such extreme conditions. Compared to deep-sea hydrothermal vents, shallow-water vents (at water depths shallower than ∼200 m) are understudied especially in the aspect of microbial communities and their role in the biogeochemical processes. Shallow-water hydrothermal systems are characterized by high temperature, high concentrations of CO2 and metals, and low pH. The presence of sunlight is an added advantage for the shallow hydrothermal vents that favor the growth of phototrophic microorganisms, such as cyanobacteria. Microbiological and geochemical studies confirmed that archaea and bacteria are at the basis of the shallow hydrothermal food chain and are involved in the transformation of inorganic compounds released from the vent emissions. This chapter will enable the researchers to understand the diversity and functions of the microbiome inhabiting in shallow-water hydrothermal vents.
