Morphometric and molecular identification of individual barnacle cyprids from wild plankton: an approach to detecting fouling and invasive barnacle species

Abstract

The present study used DNA barcodes to identify individual cyprids to species. This enables accurate quantification of larvae of potential fouling species in the plankton. In addition, it explains the settlement patterns of barnacles and serves as an early warning system of unwanted immigrant species. Sequences from a total of 540 individual cypris larvae from Taiwanese waters formed 36 monophyletic clades (species) in a phylogenetic tree. Of these clades, 26 were identified to species, but 10 unknown monophyletic clades represented non-native species. Cyprids of the invasive barnacle, Megabalanus cocopoma, were identified. Multivariate analysis of antennular morphometric characters revealed three significant clusters in a nMDS plot, viz. a bell-shaped attachment organ (most species), a shoe-shaped attachment organ (some species), and a spear-shaped attachment organ (coral barnacles only). These differences in attachment organ structure indicate that antennular structures interact directly with the diverse substrata involved in cirripede settlement.

Keywords:

• barnacle cyprids
• DNA barcoding
• invasive species
• antennular characters
• substratum preference

Acknowledgments

The authors would like to thank Pei-Chen Tsai, Chien-Hua Liu, and I-Han Chen (Academia Sinica, Taiwan) for assisting in field collection of barnacle adults and larvae. The authors also thank Chi Chiu Cheang, Hsin-Ying Lee, and Huai-Zhen Hsieh (Academia Sinica, Taiwan) for assistance with the molecular work. HNC was supported by a National Taiwan University postgraduate studentship. BKKC was supported by a grant from the National Science Council, Taiwan (NSC-99-2621-B-001-007-MY3) and Career Development Award from Academia Sinica, Taiwan (AS-98-CDA-L15). JTH was financed by the Danish Council for Independent Research (Grant 09-06 3868-FNU) and the Carlsberg Foundation (Grant 2008-01-0491). He is additionally grateful to BKKC for financing a visit to Academia Sinica.