Role of commercial harbours and recreational marinas in the spread of non-indigenous fouling species

Abstract

The role of commercial harbours as sink and source habitats for non-indigenous species (NIS) and the role of recreational boating for their secondary spread were investigated by analysing the fouling community of five Italian harbours and five marinas in the western Mediterranean Sea. It was first hypothesised that NIS assemblages in the recreational marinas were subsets of those occurring in commercial harbours. However, the data did not consistently support this hypothesis: the NIS pools of some marinas significantly diverged from harbours even belonging to the same coastal stretches, including NIS occurring only in marinas. This study confirms harbours as hotspots for marine NIS, but also reveals that numbers of NIS in some marinas is higher than expected, suggesting that recreational vessels effectively facilitate NIS spread. It is recommended that this vector of NIS introduction is taken into account in the future planning of sustainable development of maritime tourism in Europe.

Keywords:

• Commercial vessels
• fouling
• introduced species
• macrozoobenthos
• ports
• recreational boating

Acknowledgements

The authors thank the Port Authorities of the localities investigated for having permitted biological sampling; the staff of the Marine Protected Area of Tavolara Punta Coda Cavallo; Daniele Paganelli, Marco Faimali, Giuliano Greco, Giovanni Macri Giacomo Borghesi and several students for logistic support during sampling surveys. They are also indebted to Adriana Giangrande (University of Salento, Italy), Maurizio Lorenti (Zoological Station ‘A. Dhorn’, Naples, Italy) and Traudl Krapp-Schickel (Forschungsmuseum A. Koenig, Bonn, Germany) for their confirmation of taxonomic identifications. Giulia Ceccherelli and Giuseppe Guarnieri are acknowledged for advice on statistical analysis. The authors gratefully thank four anonymous reviewers for their comments that greatly improved the paper and Aylin Ulman for the English revision of the text.