Stratification or layering of the water column is a progressive disruption to a healthy water body. Deoxygenated water is denser than oxygenated water, so it sinks to the bottom and stays there. Cold water is denser than warmer water, so it sinks to the bottom and stays there.
So colder, less oxygenated water accumulates in the benthic (bottom) zone. Over time more and more layers develop as the level of cold deoxygenated water increases in the water column. Because these layers are heavier and denser they become “locked in” by gravity.
Stratification can, therefore, be quantified by measuring the temperature and dissolved oxygen levels of the water at different depths.