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In particular, compared to the subdivisions of the Marine Strategy Framework Directive, our
proposal simply splits into three the “Western Mediterranean Sea”, into two the “Ionian Sea and
Central Mediterranean Sea”, and into two the “Aegean – Levantine Sea”. This is acceptable
because the Directive states that “ … in order to take into account the specificities of a particular
area, … [it is possible to] … implement this Directive by reference to subdivisions at the
appropriate level of the marine waters … provided that such subdivisions are delimited in a manner
compatible with the following marine subregions …. (i) the Western Mediterranean Sea; (ii) the
Adriatic Sea; (iii) the Ionian Sea and the Central Mediterranean Sea; (iv) the Aegean-Levantine
Sea.”

Furthermore, compared to the ecoregional subdivision proposed by Spalding et al. (2007), our
proposal: a) splits the “Western Mediterranean” into two, considering that morphological,
oceanographic and biogeographical differences between Tyrrhenian Sea and the Algero-Provencal
basin; b) moves the boundary between Ionian Sea and Tunisian Plateau – Gulf of Sidra to more
closely reflect the depth profiles of the area; and c) moves the boundary between Aegean Sea and
Levantine Sea to ensure the correct delimitation of the former.

2.3.2 Biophysical features of the Mediterranean High Seas

The Mediterranean is a semi-enclosed sea almost entirely landlocked between Europe, Africa and
Asia. In spite of its small size compared to the world’s oceans, the Mediterranean is considered a
deep sea, with areas of seafloor exceeding the depth of 5,000 m (Fig. 2-5). The only connection
with the Atlantic Ocean is the Strait of Gibraltar, 320 m deep and 14 km wide. The Mediterranean
is also connected to the Black Sea through the Turkish Straits System, which is as shallow as 70 m
in the Bosphorus. The Mediterranean’s connection with the Red Sea, the man-made Suez
Channel, opened in 1869, is irrelevant from the point of view of water mass exchanges with the
world’s oceans, but it has become a significant corridor for biological dispersion. A north-south
ridge between Sicily and the African coast, with a minimum depth of 400 m, subdivides the basin
into a western and eastern portion. With the exception of the Adriatic and Aegean Seas, off the
coasts of Tunisia, Libya and southern Sicily, the continental shelf is very narrow and constitutes
less than 25% of the total basin area (Sardà et al. 2004).