abyssal circulation

Abyssal circulation, also known as thermohaline circulation, is the slow, deep-ocean movement of water driven by differences in temperature and salinity. This process begins in polar regions, primarily the Antarctic, where cold, dense water sinks and flows along the ocean floor toward the Equator.12

The abyssal zone itself is the largest environment for Earth's life, spanning depths between 2,000 and 6,000 meters. Waters in this zone are characterized by uniform conditions, with temperatures between 0° and 4° C and salinities ranging narrowly between 34.6 and 35.0 parts per thousand. Nutrient salts are abundant due to the decomposition of organic matter from upper zones, and oxygen levels are maintained by the initial dissolution at the surface and the lack of photosynthesis. The abyssal realm is very calm, with sediments primarily composed of plankton remains.2