Long-term effects of Caulerpa taxifolia (Vahl) C. Agardh invasion on sandy bottoms and Posidonia oceanica (L.) Delile dead matte

Abstract

Within a research project aimed to increase the knowledge on the ecology of some alien algae settled along the north-eastern Sardinian coasts, the long-term effects of the invasion by the macroalga Caulerpa taxifolia (Vahl) C. Agardh on the structure of macrofaunal assemblages were investigated at two habitats: Posidonia oceanica (L.) Delile dead matte and sand. To the purpose, for both habitats the taxonomic composition of the macrobenthic community was investigated on substrata invaded by C. taxifolia, colonized by the autochthonous congener Caulerpa prolifera (Forsskål) Lamouroux and on control substrata where no Caulerpa species were present. The study was carried out in Sos Aranzos bay, near Golfo Aranci (N-E Sardinia), in the August of 2008, six years after the species was first found in the area (2002). On the whole, the most common taxa were: nematodes, polychaetes and gastropods. No significant differences were found between assemblages, independently from Caulerpa species presence, thus suggesting that C. taxifolia invasion hasn’t produced significant long-term changes in the structure of the macrobenthic community.