Novel reverse radioisotope labelling experiment reveals carbon assimilation of marine calcifiers under ocean acidification conditions

• Published in: Methods in Ecology and Evolution
• Main Authors: Nishida, Kozue, Chew, Yue Chin, Miyairi, Yosuke, Hirabayashi, Shoko, Suzuki, Atsushi, Hayashi, Masahiro, Yamamoto, Yuzo, Sato, Mizuho, Nojiri, Yukihiro, Yokoyama, Yusuke
• Other Authors: Trueman, Clive, National Institute of Advanced Industrial Science and Technology, Core Research for Evolutional Science and Technology, Miljøministeriet, Fukada Geological Institute, Japan Society for the Promotion of Science
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2020
• Subjects: Ecological Modeling; Ecology, Evolution, Behavior and Systematics; Ocean acidification
• Online Access: http://dx.doi.org/10.1111/2041-210x.13396; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2F2041-210X.13396; https://onlinelibrary.wiley.com/doi/pdf/10.1111/2041-210X.13396; https://onlinelibrary.wiley.com/doi/full-xml/10.1111/2041-210X.13396; https://onlinelibrary.wiley.com/doi/am-pdf/10.1111/2041-210X.13396; https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/2041-210X.13396

Abstract Ocean acidification by anthropogenic carbon dioxide emissions is projected to depress metabolic and physiological activity in marine calcifiers. To evaluate the sensitivity of marine organisms against ocean acidification, the assimilation of nutrients into carbonate shells and soft tissues must be examined. We designed a novel experimental protocol, reverse radioisotope labelling, to trace partitioning of nutrients within a single bivalve species under ocean acidification conditions. Injecting CO 2 gas, free from radiocarbon, can provide a large contrast between carbon dissolved in the water and the one assimilated from atmosphere. By culturing modern aquifer organisms in acidified seawater, we were able to determine differences in the relative contributions of the end members, dissolved inorganic carbon (DIC) in seawater and metabolic CO 2 , to shell carbonate and soft tissues. Under all p CO 2 conditions (463, 653, 872, 1,137 and 1,337 μatm), radiocarbon (Δ 14 C) values of the bivalve Scapharca broughtonii shell were significantly correlated with seawater DIC values; therefore, shell carbonate was derived principally from seawater DIC. The Δ 14 C results together with stable carbon isotope (δ 13 C) data suggest that in S. broughtonii shell δ 13 C may reflect the kinetics of isotopic equilibration as well as end‐member contributions; thus, care must be taken when analysing end‐member contributions by a previous method using δ 13 C. The insensitivity of S. broughtonii to perturbations in p CO 2 up to at least 1,337 µatm indicates that this species can withstand ocean acidification. Usage of radioisotope to dope for tracer experiments requires strict rules to conduct any operations. Yet, reverse radioisotope labelling proposing in this study has a large advantage and is a powerful tool to understanding physiology of aquifer organisms that can be applicable to various organisms and culture experiments, such as temperature, salinity and acidification experiments, to improve understanding of the proportions ...