Tropical Red Sea fish colonizes the Mediterranean
Of the many exotic fish living in the Red Sea, one of the most unique and well-known is the cornetfish (Fistularia commersoni). This meter-long silvery fish resembles a long, thin flute, with a rigid, pipe-like mouth.
Until recently, anyone who wanted to see cornetfish had to go south, to the Red Sea. In the past decade, however, this fish has begun to appear in the Mediterranean Sea, where it is multiplying rapidly.
Dr. Daniel Golani of the Department of Evolution, Systematics and Ecology at Hebrew University in Jerusalem has been following the integration of the cornetfish in its new surroundings. Golani joined forces with researchers from Greece and Italy in order to understand how invading species integrate into their new environments. The findings of this study were published recently in "Biology Letters."
Here, Golani describes how the cornetfish spread in the Mediterranean - part of the broader phenomenon of various species migrating from the Red Sea to the Mediterranean Sea and colonizing there - and how the new species have completely altered the ecosystem there.
For millions of years, he explains, Mediterranean species were isolated from those of the Red Sea. Most of the Red Sea fish, including the cornetfish, are tropical fish that originated in the Pacific Ocean and the Indian Ocean (which meets the Red Sea at its southern tip). Since the opening of the Suez Canal in 1869, however, the waterway has facilitated the migration of fish from the Red Sea to the Mediterranean. There is almost no migration in the opposite direction.
This type of migration is known as Lessepsian Migration, named after Ferdinand de Lesseps, the diplomat behind and engineer of the Suez Canal.
"There has been very extensive migration via the canal," says Golani. "Some of the species have adjusted very well and have spread westward."
Golani says that on average, one new species of migrant fish is discovered annually. To date more than 250 species from the Red Sea have been found in the Mediterranean, including crabs, mollusks, worms and 69 species of fish, which now comprise some 20 percent of all the fish species in the Mediterranean.
Despite its fragile form, the cornetfish has integrated exceptionally well in the Mediterranean. The first specimen was identified by Golani off the Ashdod coast in 2000, and in the following years, cornetfish were identified in Turkish, Greek, Sicilian and Tunisian waters. They have been caught in the nets of sardine fishermen off the northwestern coast of Italy.
"We call it the 'champion colonizer,' as it has an amazing ability to adapt," says Golani. "There are now huge schools of cornetfish in the Mediterranean, and they are very easy to identify, since they are so unique."
Marine biologists have yet to find that the cornetfish invasion has caused ecological damage.
Golani's study examined genetic variations among the migrant cornetfish populations. DNA tests on about 50 cornetfish specimens in the Mediterranean revealed a very homogeneous population.
"In their natural environment, almost every cornetfish specimen we tested was genetically different from the others," says Golani. "In the Mediterranean, however, we found only two genetic variations."
This proves that the enormous cornetfish population inhabiting the Mediterranean originated from a very small group of "refugees" that crossed the canal. Golani says cornetfish are a popular food fish in the Far East, but since this is a meter-long fish with very little meat on it, it seems unlikely to become a menu item at Mediterranean seafood restaurants.
"I have not seen it at Israeli markets," says Golani. "The fishermen who catch [cornetfish] probably throw them back into the sea."