The introduction to Japan of the Titan barnacle, Megabalanus coccopoma (Darwin, 1854) (Cirripedia: Balanomorpha) and the role of shipping in its translocation

Abstract

The Titan Acorn barnacle, Megabalanus coccopoma, a native of the tropical eastern Pacific, has become established in the western Atlantic (Brazil and the northern Gulf of Mexico to the Carolinas), northwestern Europe and the western Indian Ocean (Mauritius), and therefore its dispersal capabilities are well known. This study reports its introduction to Japan and confirms its occurrence in Australia. In an attempt to determine the source of this introduction, phylogeographic techniques, involving cytochrome c oxidase I sequences of various widely separate populations of M. rosa and M. volcano, were utilized. No significant genetic differentiation or haplotype patterns between widely separated populations of each of the three species were found. Lack of such differentiation indicates recent geographical isolation and thus negates a null hypothesis predicting that the occurrence of one of more of these species in Australia was natural.

Keywords:

• Megabalanus coccopoma
• invasive species
• alien species
• haplotype analysis
• phylogeographic distribution
• Megabalanus rosa
• Megabalanus volcano

Acknowledgements

The authors wish to thank Professor Emeritus W.A. Newman, Scripps Institution of Oceanography, who kindly read the manuscript and provided invaluable comments. Thanks are due to the late Professor Emeritus T. Hanai, University of Tokyo for the giving encouragement for all T.Y.'s research. The authors also thank the late Dr P.S. Young of Brazil, and his former student, Dr F.B. Pitombo, both of whom provided specimens of Brazilian Megabalanus. They are grateful to Dr M. Saito and T. Shuto of Chiba University for invaluable advice on DNA research, Dr I. Ueda of Enoshima Aquarium and T. Shuto and M. Kikuchi of Chiba University for providing information on current geographic distribution, and R. Hayashi of Chiba University for the photography used in this article. The study was supported in part by the Global Environmental Research Fund (D-072) in 2007–2009 by Ministry of Environment, Japan to T.Y., H.K. and M.O.