Impact of Red Sea Fish Migrants through the Suez Canal on the Aquatic Environment of the Eastern Mediterranean

The invasion of Red Sea organisms through the Suez Canal, known as “Lessepsian migration” (after Ferdinand de Lesseps, the Frenchman who directed the canal’s construction), has profoundly modified the ecosystem of the Eastern Mediterranean. This migration, the result of major man-made changes in the area, has given us a unique opportunity to study the process of invasion and colonization by tropical biota of a sub-tropical region populated by temperate biota. The present research on Lessepsian fish focuses on three major areas: 1) identifying the characteristics distinguishing colonizer species from closely related non-colonizer species in the Red Sea; 2) assessing the colonizer populations’ responses to the new environmental conditions; and 3) studying the impact of the Lessepsian migration on the Eastern Mediterranean ecosystem. Impact of Red Sea Fish Migrants through the Suez Canal on the Aquatic Environment of the Eastern Mediterranean INTRODUCTION No zoogeographic marine area of the world has been affected more by man-made changes than the eastern Mediterranean. Two major projects have heavily influenced the Levantine marine ecosystem: the construction of the Suez Canal, completed in 1869, and, to a lesser extent, the Aswan High Dam. The dam, which became fully operational in 1964, resulted in the cessation of fluvial sedimentation and nutrients to the Mediterranean, leading to a sharp decrease in fish populations, mainly sardines (Aleem 1972); as a result, the Egyptian purse seine fishing industry today takes only 10% of the pre-dam catch. The Suez Canal, however, has had an even more significant and lasting impact. The opening of the Canal in 1869 has had zoogeographic and ecological ramifications far beyond those envisioned by its designers, who only intended to provide a quick trade route from Europe to India and the Far East. Stretching from Port Said in the north, the Suez Canal continues southward for 162.5 km, crossing Lake Timsah and the Bitter Lakes on its way to the city of Suez and the Gulf of Suez. For most of its length, the canal is quite narrow, only 200–300 m, and very shallow, 10–15 m. The canal connects two major bodies of water, the Red Sea and the Mediterranean, which differ fundamentally both faunistically and hydrographically. The main abiotic difference between the two regions is the temperature regime, which is stable in the tropical Red Sea but experiences wide fluctuations in the subtropical Mediterranean. The fauna of the Red Sea is of tropical Indo-Pacific origin, while that of the Mediterranean is mainly of temperate Atlantic origin. In the wake of the The opening of the Canal in 1869 has zoogeographic and ecological ramifications far beyond those envisioned by its designers, who only intended to provide a quick trade route from Europe to India and the Far East.