[A-OS15] Chemical and Biological Oceanography

[AOS15-P05] Heterogeneous shell growth of the neustonic goose barnacle Lepas anserifera: Its potential application for tracking floating materials

*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 Laboratory, Kyoto University, 4.Nara Women's University)

Keywords:biomineralization, pelagic, carbonate

Floating materials of both natural and anthropogenic origin can affect marine ecosystems and human economic activities. Although the tracking and forecasting of floating materials are important, these processes are difficult to trace back after the events of origins, such as tsunamis and underwater volcanic eruptions. The goose barnacle Lepas anserifera, a rapid colonizer in pelagic environments, is a potential "natural logger" of floating materials. In this study, we performed temperature-controlled culture experiments and growth line identification in the laboratory to quantify the growth increments of individual shells consisting of the capitulum of L. anserifera and to examine the effects of the temperature on their growth. Following calcein staining, the growth line of L. anserifera was visualized under a fluorescent microscope, and gross (capitular length and width) and individual (scutum and tergum) shell growth were compared. Shells grew in twice as much in the CL direction than in the CW direction owing to the larger growth increases in the scutum than in the tergum. Growth increments were unaffected by temperatures from 20°C to 30°C, although growth appeared somewhat limited after August. The stable oxygen isotope composition (δ18O) of the shells represented the water temperature as previously known, and the present results showed that the scutum had heavier δ18O than the tergum in most cases. Further understanding for the biomineralization process of barnacles is required for the precise application of environmental proxies in barnacle shells.