An outbreak of the invasive macroalgae Rugulopteryx okamurae in Alicante Bay and its colonization on dead Posidonia oceanica matte

Abstract

We report the first occurrence of Rugulopteryx okamurae in Alicante Bay, the northernmost location in the Iberian Mediterranean where this species was detected. Collected specimens were studied using a morphological and molecular approach. A rapid assessment survey was conducted to assess its presence and abundance in the nearest beach-cast and infralittoral areas. The highest abundance was found over dead P. oceanica matte, occupying an important extension in the bay. We found detached fragments of R. okamurae dispersed by local hydrodynamics, accumulating on some tourist beaches in the region. The potential suitability of the Mediterranean for its spread necessitates monitoring programs to study its variation over time and potential impacts on native biota.