Mysterious marine invasive species, what we know about the ocean’s greatest threats

The mud snail, the lionfish, sponges, starfish: science hasn't studied them enough. We know too little about invasive species, a great threat to the seas.

They are called invasive species: we know what they are and we know why they pose a threat to the marine ecosystem.

They are, for example, the lionfish or the mud snail. The former is a very beautiful but equally venomous animal that, since it was spotted in the Indo-Pacific Ocean in the 1980s (outside of where it used to live), has taken mangrove forests, coral reefs and kelp meadows in the Caribbean by storm, raising enough of an alert that it has become the face and symbol of marine invasive species.

"Probably the most insidious threat" to marine biodiversity, is how the International Union for Conservation of Nature has defined invasive species. "I think science sometimes comes across as having all the solutions, right? This is a paper that tells us there's a lot we don't know." Those are the words of Isabelle Côté, a marine ecologist at Simon Fraser University in British Columbia and author of a troubling new study on invasive species.

What the new study on marine invasive species says

For ten years, Isabelle Côté has watched lionfish wreak havoc on Caribbean ecosystems. After a series of extensive research on the Indo-Pacific threat, she began to take a closer look at another species, the mud snail. So he took a step back and tried to look at the problem from a more general perspective. The conclusions of his latest analysis can be found in a new study: together with colleagues, he reviewed the existing scientific literature, showing that, of the approximately 970 marine species considered invasive, more than half (55 percent) have been studied only once and 8 percent have been studied more than 10 times.

What are the most-studied and least-studied invasive marine species

The beacon of science often turns on fish and shellfish, the primary subjects of 50 percent of observations. Sea cucumbers, sponges, and starfish, on the other hand, mostly swim in the darkness of our analytical knowledge. Differences have also been identified within each group: we know of four species of invasive ctenophore, but only the sea nut has been examined 80% of the time.

The ocean is full of mysterious and sometimes bizarre specimens, which scientists have sometimes managed to bring to the surface: it was for example the fish with human teeth or the living fossil, an animal that can live up to 100 years.

Giuseppe Giordano