Japan Geoscience Union Meeting 2018

Presentation information

[JJ] Evening Poster

M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS10] Paleoclimatology and paleoceanography

Wed. May 23, 2018 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall7, Makuhari Messe)

convener:Yusuke Okazaki(Department of Earth and Planetary Sciences, Graduate School of Science, Kyushu University), Atsuhiko Isobe(Research Institute for Applied Mechanics, Kyushu University), Akihisa Kitamura(静岡大学理学部地球科学教室, 共同), Masaki Sano(Faculty of Human Sciences, Waseda University)

[MIS10-P28] Effects of ocean acidification on growth and spinous skeletal composition of the sea urchin (Mesocentrotus nudus, Strongylocentrotus intermedius)

*Riki Miyai1, Tsuyoshi Kuroda1, Daisuke Muraoka2, Hideki Takami2, Atsushi Suzuki3, Yukihiro Nojiri4, Mayuri Inoue1 (1.Graduate School of National Science and Technology, Okayama University, 2.Tohoku National Fisheries Research Institute, 3.National Institute of Advanced Industrial Science and Technology, 4.Hirosaki University)

Keywords:sea urchin, trace element, ocean acidification

Since the Industrial Revolution, ocean acidification has advanced owing to the dissolution of anthropogenic carbon dioxide (CO2) released into the atmosphere into sea water, and there are concerns about the impact on many marine ecosystems. Particularly, for organisms forming calcium carbonate (CaCO3) shells and skeletons, since carbonate ion concentration decreases during the ocean acidification, it is predicted that skeleton formation becomes difficult and adverse effect will be exerted. However, many creatures have not been evaluated for their impact. Therefore, in this study, we investigated the influence of acidification based on the change of the chemical composition and structure of the spines of Mesocentrotus nudus and Strongylocentrotus intermedius in which calcite is the main component of spines and shells.
In this study, the sea urchins were raised under the following five carbon dioxide partial pressures (pCO2, μatm): (i) 2000, (ii) 1000, (iii) 700, (iv) 350 (controlled setting) and (v) 250. The settings of pCO2 from (i) to (iii) were adjusted by addition of CO2 and condition of (v) was adjusted chemically. Five to seven sea urchins were placed in individual bottles in each setting and were raised for more than 6 months for M.nudus and S. intermedius, respectively. The shell length and the weight was measured monthly. The chemical components (Mg, Sr and Ca) in the spines were measured with an inductivity coupled plasma optical emission spectrometry (ICP – OES). Also, the surface and cross-sectional structure of the spines was observed using a scanning electron microscope (SEM).
As the result of culture experiments, the shell length and body weight of both species decreased with increasing pCO2. In addition, the Mg/Ca ratios of the spines were relatively higher at higher pCO2 settings. The mean Mg/Ca ratio of M. nudus was about 1.4 times higher than that of S. intermedius. As solubility increases for calcite with increasing of Mg content, it is suggested that the spines of M. nudus are more likely to dissolve or making calcification less likely to occur in the future ocean acidification. On the other hand, the Sr/Ca ratio was not clearly related to the pCO2 condition. Although, in general, the sea urchin spine has a stereomorphic structure with countless holes and such structure was found in the spines reared under controlled setting, the hole filled probably by calcite in the stereomorphic structure was observed in the spines reared under higher pCO2 settings. Therefore, intense ocean acidification would affect negative impacts on growth of spines of sea urchins.