The oceans are divided into warm warm vs cool water realms at the 18 degree C marker.

Warm Water systems:
-typically in low latitudes
-the photic zone extends to about 70m
-carbonate production is highest in the upper 10-20m
-produces Chlorozoan assemblages of organisms

Cool Water systems:
-the photic zones plays little role in carbonate production
-lower sedimentation rate than the warm water factories
-produces Foramol assemblages of sediments

Salinity
Both organismal assemblages succeede in salinities ranging from 32 to 40 ppt.
When the salinity increased above 40 ppt in the tropics the organism assemblage becomes Chloralgal.
Increasing the salinity above normal ocean levels reduces the biotic diversity that can handle an extreme amount of salt.