Page "Suez Canal" Paragraph 79

The opening of the Suez Canal in 1869 created the first salt-water passage between the Mediterranean and Red seas.

Although the Red Sea is about higher than the eastern Mediterranean, the current between the Mediterranean and the middle of the canal at the Bitter Lakes flows north in winter and south in summer.

The current south of the Bitter Lakes is tidal, varying with the height of tide at Suez.

The Bitter Lakes, which were hypersaline natural lakes, blocked the migration of Red Sea species into the Mediterranean for many decades, but as the salinity of the lakes gradually equalised with that of the Red Sea, the barrier to migration was removed, and plants and animals from the Red Sea have begun to colonise the eastern Mediterranean.

The Red Sea is generally saltier and more nutrient-poor than the Atlantic, so the Red Sea species have advantages over Atlantic species in the salty and nutrient-poor eastern Mediterranean.

Accordingly, most Red Sea species invade the Mediterranean biota, and only few do the opposite.

This migratory phenomenon is called Lessepsian migration ( after Ferdinand de Lesseps ) or Erythrean invasion.

Also impacting the eastern Mediterranean, starting in 1968, was the operation of Aswan High Dam across the River Nile.

While providing for increased human development, the project both reduced the inflow of freshwater and ended all natural nutrient-rich silt from entering the eastern Mediterranean at the adjacent Nile Delta.

This provided less natural dilution of Mediterranean salinity and ended the higher levels of natural turbidity, additionally making conditions more like those in the Red Sea.