it is because of a plant named “gonyaulax{dinoflagellate}” which is present in the sea.it imparts red color to sea. read more
The Mediterranean sea does have tides, but they are of a very low amplitude, as you can see somewhat in the below diagram (from Legos via Aviso/Altimetry) where the Mediterranean is mostly shown in blue meaning its tides have an average amplitude of a few centimetres, (instead of the metre of so shown in the part of the atlantic you can see). read more
Well i lived on the Black Sea and saw tidal movement at Sinop and at Istambul on the Bosphorus, so there were tides between the Black sea and the Mediterranean; - also at Gibraltar there are tides, also from standing at a few costal spots near (Naples) i would say there are small tides - just not much movement at Sinop and Naples. read more