Calanques of Marseille: an invasive alga from Japan proliferates

An alga is proliferating rapidly in the Callelongue cove in Marseille (Bouches-du-Rhône). Identifiable by its size and its green color, its presence worries.

An algae covers everything on 60 cm height, and forms an opaque greenish carpet. Today, the Calanque of Callelongue is far from the picture postcard image. The inhabitants wonder about the danger of the algae. A marine biologist identified the invasive specimen. "It is a biological invasion, it is an introduced species that comes from Japan, which is called rugulopteryx okamurae", specifies Thierry Thibaut, teacher researcher at the MIO.

Present since the years 2000

This Asian variety was observed for the first time in the Mediterranean in the early 2000s. Since, it proliferates on the Spanish and French coasts. In two years, the alga has colonized several kilometers of the Marseilles coastline. The colonization worries the Calanques National Park. A study has begun to assess the risks to the fauna and flora.

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