Editing Ocean Drilling Program (section)

=== Biological Processes ===
Prior to the ODP, there was little definitive evidence confirming whether or not bacterial populations exist in subseafloor sediments.<ref name=":4">{{Cite journal |last1=Parkes |first1=R. John |last2=Cragg |first2=Barry A. |last3=Wellsbury |first3=Peter |date=2000-03-13 |title=Recent studies on bacterial populations and processes in subseafloor sediments: A review |url=http://link.springer.com/10.1007/PL00010971 |journal=Hydrogeology Journal |language=en |volume=8 |issue=1 |pages=11–28 |doi=10.1007/PL00010971 |bibcode=2000HydJ....8...11P |issn=1431-2174|url-access=subscription }}</ref> 14 sites of the ODP focused specifically on studying bacteria, and the program's technology was able to collect core samples that were undisturbed and not contaminated to accurately examine bacterial populations and their activities.<ref name=":4" />

==== Presence and Activities of Bacterial Populations ====
Evidence from the ODP contradicted expectations that biological activity is more heavily concentrated near Earth's surface.<ref name=":4" /> Large populations were discovered, which added around 10% to global [[biomass]] estimates.<ref name=":4" /> The abundance of bacterial populations decreased with depth, and deeper bacteria had slower growth rates.<ref name=":4" /> Despite this overall trend, there were certain geochemical conditions and [[Thermogenics|thermogenic]] processes that allowed bacterial populations to thrive at depth.<ref name=":4" /> For example, near gas hydrate deposits, rates of methane oxidation increased due to the abundance of organic carbon present.<ref name=":0" /><ref name=":4" /> Additionally, the rates of [[methanogenesis]] and acetate [[metabolism]] increased in bacteria in the subsurface compared to those near the surface.<ref name=":4" />

==== Bacterial Motility ====
Another biological process that was examined was the [[motility]] of these bacterial populations. Scientists hoped to better understand if bacteria were trapped in deposited sediments or able to move freely throughout the subsurface.<ref name=":4" /> Evidence from the ODP showed that bacteria closer to the surface were motile, while those in deeper sediments were unable to keep up with sedimentation deposit rates and became buried.<ref name=":4" />