Pinctada radiata spreads to the Balearic Islands

Researchers at the Spanish National Research Council reported in València, Spain, on 19 August 2026 that the invasive pearl oyster Pinctada radiata is expanding across the western Mediterranean. The species was first detected by the monitoring network in the Balearic Islands, Spain, in 2016, with records along Spain’s coast now extending from southern Catalonia to Agua Amarga in Almería.

The study was coordinated by Diego Kersting of the Institute of Aquaculture Torre de la Sal, part of the Spanish National Research Council. Its network of 132 monitoring sites in eight Mediterranean countries tracked the oyster’s spread between 2015 and 2024.

Larval collectors provide early warning

The network uses mesh collectors that provide a surface for larvae carried by currents to settle on. Researchers say these devices can reveal the arrival of Pinctada radiata years before it becomes established in natural habitats.

At the Columbretes Islands marine reserve off Castellón, the oyster was found in collectors in 2020, but was not recorded as established in the natural environment until 2022. The collectors have been used there since 2003 to study the critically endangered Mediterranean fan mussel, Pinna nobilis.

Sea warming aids westward expansion

Native to the Red Sea, Pinctada radiata entered the Mediterranean through the Suez Canal in the 19th century. It is listed among the 100 most dangerous invasive species in the Mediterranean because of its potential effects on native biodiversity and food chains; in the eastern Mediterranean it has already displaced local species.

Researchers link its expansion to rising sea temperatures and the species’ ability to disperse widely as larvae. The Mediterranean is warming three times faster than the global average, while waters around Sa Dragonera, Mallorca, have recently reached 33 degrees. The Gulf of Lion and the northern Adriatic remain free of the species, according to the research team.

Topics: Politics

Source: Europa Press / Mallorca.com