CALCIFICATION IN A CHANGING OCEAN: AN EVALUATION OF METHODS FOR DETECTING CHANGES IN COCCOLITHOPHORE PIC:POC

Changes to coccolithophore particulate inorganic and organic carbon ratios PIC:POC under projected ocean acidification conditions has been shown to be species and strain specific. Accurate direct measurements of coccolithophore PIC:POC is essential to understanding their role in global ocean carbon flux. In laboratory experiments, measurements of POC are obtained by acid decalcification of filters, typically using fuming HCl before CN Analysis. However, no standard operating procedure exists for decalcification or verifying complete CaCO₃ dissolution. We systematically tested the efficacy of acid decalcification for several species prior to CN analysis, by examining factors such as fuming wet or dry filters, fume duration, and whether there is a difference between acid fuming or direct addition of acid to filters. Scanning electron microscopy confirmed complete decalcification regardless of time, with no significant difference in PIC:POC ratios between 30 min and 24 h. Direct addition of 0.5M HCl to wet filters also yielded complete decalcification across all species and cell densities with less variation in subsequent CN analysis. Moreover, we show that the direct addition method is sensitive enough to resolve PIC of haploid holococcolith bearing strains and can detect changes in PIC:POC in response to ion channel blockers that are crucial for calcification and pH homeostasis. We provide recommendations for obtaining accurate and precise PIC:POC ratios for a range heavily and lightly calcified 2N & N coccolithophores.

Presentation Preference: Oral

Primary Presenter: Madison Cox, Department of Biology and Marine Biology, University of North Carolina Wilmington, USA (mbc5962@uncw.edu)

Authors:

Madison Cox, Department of Biology and Marine Biology, University of North Carolina Wilmington, USA  (mbc5962@uncw.edu)

Alison Taylor, Department of Biology and Marine Biology, University of North Carolina Wilmington, USA  & Richard M Dillaman Biological Imaging Facility, University of North Carolina Wilmington, USA  (taylora@uncw.edu)

Robert Whitehead, Center for Marine Sciences, University of North Carolina Wilmington, USA  (whiteheadrf@uncw.edu)