Mediterranean Sea: Enclosed Basin with Unique Climate, High Salinity, and Rich Biodiversity

The Mediterranean Sea is a semi-enclosed basin connecting to the Atlantic only through the Strait of Gibraltar.

Geography

• Crossroads of Europe, Asia, Africa
• Largest enclosed sea (~2.5 million km²)

Climate

• Mediterranean: hot, dry summers; mild, wet winters
• Avg Jan: 10°C; Avg Jul: 25°C; Precip: ~500 mm/yr

Circulation

• Western Basin Cyclonic (WBC)
• Eastern Basin Cyclonic (EBC)
• Atlantic inflow at surface; Mediterranean outflow at depth

Depth & Salinity

• Avg depth: 1,500 m
• Max depth: 5,267 m (Calypso Deep, Ionian Sea)
• Salinity: 37.4% (vs. Atlantic 35%) – high evaporation, low river input

Tides

Very small (<0.5 m range).

Biodiversity

• ~17,000 species (20% of known marine species)
• High endemism: ~50% fish, ~33% plants unique to Mediterranean

The Mediterranean is a biodiversity hotspot under intense anthropogenic pressure.