Explanation:

The vertical zone in the oceanic water column in which salinity changes rapidly with depth, is known as Halocline.
In oceanography, a halocline (from Greek hals, halos 'salt' and klinein 'to slope') is a subtype of chemocline caused by a strong, vertical salinity gradient within a body of water. Because salinity (in concert with temperature) affects the density of seawater, it can play a role in its vertical stratification.