Marine Biodiversity Records

Research Article

New record of the alien seagrass Halophila stipulacea (Hydrocharitaceae) in the western Mediterranean: a further clue to changing Mediterranean Sea biogeography

Maria Cristina Gambia1 c1, Fabio Barbieria2 and Carlo Nike Bianchia3

a1 Laboratorio di Ecologia del Benthos – Stazione Zoologica Anton Dohrn, Napoli, Italy

a2 Palinuro Sub, Via Porto, Palinuro (Salerno), Italy

a3 DipTeRis (Dipartimento per lo studio del Territorio e delle sue Risorse), Università di Genova, Corso Europa 26, 16132 Genoa, Italy


The occurrence of the tropical seagrass species Halophila stipulacea (Hydrocharitaceae) is reported within the harbour of Palinuro (Salerno, central Tyrrhenian Sea, Italy). The bottom covered by the seagrass has been evaluated in about 16 m2, fragmented in various small patches distributed in a narrow belt between 0.5 and 5 m depth, and all settled on dead matte of the endemic Mediterranean seagrass Posidonia oceanica. Mean density was 10,500 shoots m−2. This record documents a displacement of about 180 km north of the previously documented limit of Halophila stipulacea in the western Mediterranean, likely mediated by pleasure boat traffic and anchoring, and favoured by climate change. This record illustrates a further example of the changing Mediterranean Sea biogeography: north–south patterns in biotic ranges will probably replace the presently well established west–east patterns in the Mediterranean Sea of tomorrow.

(Received November 07 2007)

(Accepted April 05 2008)


  • marine angiosperms;
  • introduced species;
  • Halophila stipulacea;
  • Tyrrhenia Sea;
  • climate change


c1 Correspondence should be addressed to: M.C. Gambi, Laboratorio di Ecologia del Benthos – Stazione Zoologica, Anton Dohrn, Napoli, Italy email: