Chemoautotrophic microbes -- bacteria that use chemical
energy instead of sunlight to make new organic compounds -- form the base
of the food chain in these communities.
Hydrocarbon seeps, abundant in sulfide and methane, provide
a favorable environment for these microbes. They can be present as bacterial
mats, or living symbiotically in other organisms to help them live in this
environment. The presence of these microbes, which sustain the different
communities at the seeps, is dependent on what type of chemical energy is
available. The type of community in an area may be explained by the chemistry
found in the area.
To try and answer some of these questions is why scientists
collect organisms, water and sediment samples. | 
