The Scorpion Fish: A New Inhabitant Of The Mediterranean Sea
The scorpion fish is the first exotic species to have invaded the coral reef of the Atlantic Ocean, multiplying at rates never seen before in the history of the seas. Now it threatens the marine ecosystem of the Mediterranean.
The scorpion fish ( Pterois miles) belongs to the poisonous fish genus Pterois and is native to the Indo-Pacific. It is also known by other names, such as lionfish or flying rockfish, and is characterized by an eye-catching coloration made up of red, white or black bands. It also has showy pectoral fins and lateral fins equipped with poisonous spines.
It should be noted that the genus Pterois includes a total of twelve species, among which the most studied are P.radiata , Pterois volitans and Pterois miles . The species of this genus have always had commercial success as an aquarium species thanks to their showy and exotic appearance. Let’s find out more about the scorpion fish!
Where does this predator come from?
The scorpion fish lives in coastal waters at depths ranging from 2 to 80 meters. It is native to the Indian Ocean and is widespread in particular from eastern Africa, from Somalia to Port Alfred, in South Africa.
It is also present from South Africa to the Red Sea and the Persian Gulf, and further east to Sumatra, Java and Bali. Additionally, scorpion fish can be observed in both the western and central Pacific as well as in Western Australia.
The scorpion fish is an invasive species
It should be emphasized that in its region of origin, the species is not particularly abundant. However, both the scorpion fish and the red scorpion fish have had unprecedented success after their introduction into the Atlantic Ocean.
In fact, the introduction of these species has proved to be one of the fastest and most ecologically harmful marine invasions recorded to date. After several studies of the genetic diversity of the invaders, it was concluded that they come from a small population from the southern United States.
In the western Atlantic, lionfish has become the dominant predator of coral reefs, with a strong impact on native fish. It is estimated that in just 2 years, it has managed to reduce the populations of as many as 40 species.
Why is it successful as an invader?
According to experts, its dramatic success as an invasive species is the result of a combination of several factors;
- For one thing, scorpion fish is a general carnivore and can feed on a wide variety of fish and crustaceans.
- Females lay eggs every 4 days throughout the year, producing around two million gelatinous, floating eggs annually. It should be noted that the eggs are planktonic and travel along ocean currents, thus covering great distances.
- The species matures and reproduces precociously and is endowed with a powerful poisonous defensive system against predators. One of its main physical characteristics are precisely the threatening and highly poisonous spines, which constitute a good defense against ectoparasites.
- Its natural predators are often among the cases of overfishing.
- Finally, the “new” prey of the scorpion fish are not used to its presence, making it less complicated the role of predators.
Did scorpion fish land in the Mediterranean Sea?
Until now, lionfish had only been warned occasionally in the eastern Mediterranean Sea. In fact, unfavorable oceanographic conditions are believed to have limited the dispersal of its larvae.
Over the past 5 years , the threat of lionfish invasion in the Mediterranean Sea appears to have become real. Sightings of this species along the coastal waters south of Cyprus are increasingly frequent.
It is important to point out that the marine ecosystems of the Mediterranean face, in addition to invasions by exotic species, many other threats such as climate change and intensive fishing. The constant increase in water temperatures certainly does not help, also favoring the proliferation of exotic species and causing changes in biodiversity and tropicalization phenomena.
There are currently more than 1000 exotic species in the Mediterranean, most of which are thermophilic and have landed via the Suez Canal. The recent expansion of the canal, together with the warming of the sea surface, are circumstances that favor the installation of scorpion fish in our waters.
Final reflection
The Mediterranean Sea is an important reserve of oceanic diversity where approximately 17,000 species inhabit. The impact of lionfish as an invasive species will lead to significant habitat changes and the reduction of local biodiversity.
Being an excellent predator, scorpion fish will reduce the abundance of biota in our marine system. In general, it is not yet possible to assess its long-term socio-economic impact. But one thing is certain: humans are truly responsible for the expansion of invasive species.
