An Outbreak of the Invasive Macroalgae Rugulopteryx Okamurae in Alicante Bay and its Rapid Spread on Dead Posidonia Oceanica Matte

Abstract

Rugulopteryx okamurae is a widely distributed species in the Asia-Pacific region which has been recently introduced in the Mediterranean Sea. In 2002 it was first detected at Thau Lagoon, not behaving as an invasive species.  However, new introductions on the coasts of Marseille, Alboran Sea and the Macaronesian region showed overgrowing in most native algal communities, having an impact on artisanal fishing, and affecting a wide bathymetric range.We report the first occurrence of R. okamurae in Alicante Bay, which means it is the northernmost location in the Iberian Mediterranean where this species was detected. Collected specimens in the area were studied from a morphological and molecular approach. A rapid assessment survey was carried out in order to evaluate the presence and abundance of this alga in the nearest beach-cast and infralittoral.The highest abundance of this species was found over dead P. oceanica matte, occupying an important extension in the bay. As in previous colonized locations, R. okamurae fragments were found detached, being dispersed due to the local hydrodynamism, and arriving and accumulating in some tourist beaches of the area.The potential suitability of the Mediterranean for the spread of R. okamurae makes it necessary to monitor programs studying its variation over time and its possible effect on the native biota.

Keywords: exotic species, non-indigenous macroalgae, Rugulopteryx okamurae, Mediterranean Sea, dead Posidonia oceanica matte