Effects of Caulerpa cylindracea Sonder (Chlorophyta Caulerpaceae) on marine biodiversity

The chief purpose of Marine Protected Areas (MPAs) is biodiversity conservation. The effects that invasive alien species (IAS) have on MPAs are not yet fully known, even though assessing them is fundamental. Effective management plans, indeed, also require knowledge on the dis- tribution, spread dynamics and impact of IAS. We report first observations on the effects of Caulerpa cylindracea Sonder (Chlorophyta Caulerpaceae) on the communities living along the coasts of the Island of Favignana (Egadi Islands MPA, Sicily, Italy). We found that C. cylindracea may have negative effects on the habitat where it settles in two different ways: a) affecting the structure of the native algal community which presents a low diversity, and b) favouring the settlement of other alien species such as Branchiomma bairdi (McIntosh, 1885) (Polychaeta Sabellidae).