Recreational boats brought in 12 new marine organisms to Maltese yacht marinas from other oceans, a study has found.
The research was a collaborative effort between a number of marine biologists across the Mediterranean, including Maltese professor Alan Deidun, and took a year-and-a-half to complete.
Of the 12 marine invertebrates recorded, three are moss animals, four are crustaceans, two are polychaetes, one is a sea squirt, one is a sea spider and one is a mollusc. Six of these hail from the Indian and Pacific Oceans and four come from the Atlantic.
Not all of these invertebrates are harmful, but some can be undesired and invasive, disrupting the ecosystem of the hull, Prof. Deidun said.
In all, 51 new non-indigenous species were found within Mediterranean recreational marinas.
Marine organisms ‘hitchhike’ a ride from one harbour to the next
The research focused on non-indigenous marine invertebrates that live and grow on artificial walls. Known as fouling organisms, these alien species colonise the hull of the boat, moving from harbour to harbour.
The study collected samples from over 600 hulls and 34 yacht marinas from Cyprus to Spain. Fishermen at the Msida and Vittoriosa yacht marinas were interviewed and asked about the boat’s travel history and the last hull cleaning, and their boats were also sampled.
Yacht marinas and recreational boats play a key role in the invasion process, the study concluded.
Fishing boats and sailing boats act as a stepping-stone in the transfer of alien species, allowing these marine organisms to ‘hitchhike’ a ride from one harbour to the next, Prof. Deidun said.
Marine biologists and sailors alike have always looked at commercial boats as the culprits for alien invasion, bringing in foreign species from the Atlantic and the Pacific. But this study has proven that recreational boats also play a role in the movement of foreign species, Prof. Deidun continued.
Control of these exotic animals is “virtually impossible,” particularly with recreational ships moving from one yacht marina to the next.
The Mediterranean is home to over two-thirds of the world’s boat traffic and hosts around 1.5 million recreational boats.
Not all of these invertebrates are harmful, but some can be undesired and invasive, disrupting the ecosystem of the hull. Around 10 per cent of them are “problematic”, Prof. Deidun said.