[B-PT03] Biomineralization and Geochemistry of Proxies

[BPT03-P05] Shell growth of a neustonic goose barnacle Lepas anserifera

*Hiromi Kayama WATANABE¹, Yukiko Nagai¹, Saburo Sakai¹, Genki Kobayashi², Luna Yamamori³, Noriko Tada¹, Haruka Nishikawa¹, Tatsu Kuwatani¹, Haruka Uehara⁴, Yoichi Yusa⁴ (1.Japan Agency for Marine-Earth Science and Technology, 2.Ishinomaki Senshu University, 3.Seto Marine Biological Station, Kyoto University, 4.Nara Women's University)

The gooseneck barnacle Lepas anserifera is a common sessile animal on floating materials in open ocean in temperate water around Japan, as it is able to settle on floating materials within about two weeks after its introduction. Barnacle is a sessile crustacean which grows symmetrically with multiple calcareous shells accretionary, and its neustonic lifestyle has been independently arise in multiple lineages of barnacles, since it radiated in Mesozoic ocean. Recent days, barnacles could be found on both of natural and anthropogenic floating materials in marine environments, such as seaweeds, woods, pumices and plastics. The shell growth manner seems to be completely different from those observed in the other animals such as mollusks and foraminiferans, as they have multiple shells in both side of body. Only a few studies attempted to reveal the details of the shell growth of L. anserifera to use it as proxy of environmental conditions, though it is still unclear. In this presentation, we review the knowledge on the shell growth of barnacles and introduce our recent findings based on the culture experiments of L. anserifera, including inter- and intra-individual variation of growth size and rate, and stable isotopic compositions of the barnacle shells.