Microbial cells are found in abundance in marine sediments beneath the ocean and make up a significant amount of the total microbial biomass on the planet. Microbes found deeper in the ocean, such as in hydrocarbon seeps, are usually believed to have slow population turnover rates and low amounts of available energy, where the further down a microbe is found, the less energy it has available.
Click here for original story, Study looks at life inside and outside of seafloor hydrocarbon seeps
Source: Phys.org