You could increase the salinity of the ocean by adding salt or removing water (ie: by evaporation).
Arctic ocean
salinity
In open ocean evaporation affects the salinity of the oceans, in closed oceans the lack of sunrays cause greater salinity levels.
salinity
The lowest areas of salinity in an ocean are near where fresh water rivers empty into them. This is because the influx of fresh water creates an area of lower salinity compared to the remainder of the ocean.
An increase in ocean salinity can increase density creating a convection current.
Salinity in the ocean is highest in regions where evaporation is high and precipitation is low. Density in seawater is determined by both temperature and salinity.
Salinity is increased.
the ocean salinnity
artic
Its salinity.
Chitin.