What are Lessepsian migrants?

Lessepsian migrants are invasive marine species that are “traveling” via the Suez Canal by water flow or maritime transport from the Red Sea to the Mediterranean Sea. When they succeed in colonizing their new environment, they impact marine ecosystems of the Mediterranean. In fact, they then have crossed a once natural land barrier between the Indian Ocean and the Atlantic Ocean. Therefore, the ecological influence of Lessepsian migrants will reach beyond the Mediterranean. The blue-spotted cornet fish may become the first Red Sea species to reach Gibraltar and even move farther [1].

The anthropogenically caused Lessepsian migration is named after the French diplomat and administrator Ferdinand de Lesseps (1805 - 1905), who was inspired by Napoleon's abandoned plans for a canal through Egypt that would shortcut the long sea journey around the southern tip of Africa [2].

The blue-spotted cornet fish is just one example of a Lessepsian migrant. Tiger prawns, mackarel and poisonous pufferfish are further examples—affecting not only ecosystems but humans, beneficially and otherwise. In her book with the title “Spineless,“ Juli Berwald explores facts and secrets of jellyfish [1]. The nomadic jellyfish is thought to be a Lessepsian migrant. Massive blooms of nomadic jellyfish have been witnessed off the Mediterranean coast. Spineless or not, species continue invading the eastern Mediterranean. Juli Berwald describes Lessepsian migration as follows:

The number of new invasive species in the Mediterranean has doubled in the last two decades. Over four hundred species have traveled the Suez from the Red Sea to the Mediterranean and established populations there. Together they have earned their own name, Lessepsian migrants, which recalls the Frenchman who envisioned and developed the Suez Canal, Ferdinand de Lesseps. Because of the flow pattern in the canal, only a few species have made the reverse passage from the Mediterranean to the Red Sea.                                                                 Juli Berwald, 2017

Keywords: marine biology, non-native species, invasion, terminology.

References and more to explore

[1] Juli Berwald: Spineless. Riverhead Books, New York, 2017.
[2] BBC History: Ferdinand de Lesseps (1805 - 1894). Link: https://www.bbc.co.uk/history/historic_figures/de_lesseps_ferdinand.shtml.