Almost half (45%) of the petroleum entering the marine environment is from natural seeps rather than anthropogenic sources. At seeps, oil and gas bubble out of cracks in the seabed creating special environments in which new organisms grow. These organisms survive through chemosynthesis rather than photosynthesis. They live in total darkness, more than four hundred meters below sea level, but survive by feeding directly off the hydrocarbons present in seeps or by eating carbon compounds resulting from chemosynthetic bacterial degradation of seep oil. Since 1984 oceanographers have discovered chemosynthetic communities of clams, mussels, tubeworms, bacterial mats, and other organisms on the seafloor of the Gulf of Mexico. United States Department of the Interior regulations protect these chemosynthetic communities from damage due to oil and gas drilling activities.
Last date updated on January, 2021