The Israeli oceanographical institute
The Israeli Oceanographic Institute in Haifa has measured The Ph in The Mediterranean sea In The last 20 years.
At the graph below - you can see that in the last years the Ph level has decreased. It is an interesting phenomena because the increasing Co2 should lead to acidification.
I estimate it could happen from many reasons - the influence of Suetz canal, the water heating, and influence of other gases.
At this video you can learn about sea-water acidity and it's influence