Subject: What has the greatest effect on density of seawater: degrees or salinity?

We are discussing the Mediterranean effect in the 8th grade science 
class in which I am student teaching.  Having more knowledge in 
biology than earth science, I found myself at a loss when a student 
asked about the differences between the temperature and salinity 
effects on ocean water density.  We have established that more 
salt-greater density and lower temperature-greater density, but which 
causes the sea water to sink the most, very high salt concentrations 
or very low temperatures?  

Re: What has the greatest effect on density of seawater: degrees or salinity?