Near-bottom currents and oxygen concentrations

Most of the deep waters in contact with the abyssal sediments are a mixture of North Atlantic and Antarctic bottom-water masses. They are relatively saline and fairly cold (0.5-1.5°C). Currents at these depths typically are slow and do not impose shear stress of sufficient magnitude to transport sediments (Gardner etal., 1984 Demidova, 1999). 

Although bottom-water masses are relatively old in the NEPAP, bottom-water oxygen concentrations remain well above 2mil-1 and hence they probably do not influence benthic community structure (Levin Gage, 1998). In the eastern tropical Pacific, oxygen-minimum zones appear in mid-water (100-1000m) due to intense water column decomposition but they do not extend to abyssal depths (Wishner etal., 1990). 

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