Effects of Ocean Acidification on Large Benthic Foraminiferal

Effects of Ocean Acidification on Large Benthic Foraminiferal Stable Isotope Composition Paul O. Knorr, Ph. D. , Bureau of Ocean Energy Management Lisa L. Robbins, Ph. D. , U. S. Geological Survey Jonathan Wynn, Ph. D. , University of South Florida Pamela Hallock, Ph. D. , University of South Florida Peter J. Harries, Ph. D. , North Carolina State University Article submitted to ICES-JMS 1 of 1

8. 0 Ωcalcite Control (p. H 8. 0, Alkalinity is 10% CO 32 -, ~2025) 4. 4 Treatment (p. H 7. 6, 4% CO 32 -, ~2140) 2. 0 0 2 470 1300 p. CO 2 (µatm) 3000

Large Benthic Forams Miliolid (Miliolida) 3 Rotalid (Rotaliida) Porcelaneous Hyaline Imperforate Perforate High-Mg calcite Low-Mg calcite Archaias angulatus Amphistegina gibbosa 2 mm

Miliolid Calcification 4 Modified after Ter Kuile et al. (1989) and Cotey and Hallock (1988)

Rotalid Calcification 5 Modified after Kuile et al. (1989) and De Nooijer et al. (2014)

Sample Location Miliolid Rotalid 6

Apparatus p. H and Alkalinity analysis using Ocean Optics spectrophotometers Stable isotope analysis using Thermo Delta V IRMS w/ Gasbench II, 2σ < 0. 1 ‰ Referenced Guide to best practices for OA research and data reporting (2010) 7

Tank Chemistry 8

Results n = 30 9

Results 2 Miliolid p. H 7. 6 Miliolid p. H 8. 0 1 Rotalid p. H 7. 6 δ 18 O -2 0 -1 0 1 -1 Rotalid p. H 8. 0 10 -2 δ 13 C

Significance δ 18 O Miliolid p < 0. 005 Rotalid p < 0. 005 δ 13 C NS (p = 0. 25) p < 0. 001 Tukey’s pairwise method 11

Interpretation Miliolid δ 18 O fractionation dependent on carbon speciation: HCO 3 - 16‰ > CO 32(Less CO 32 - at low p. H) δ 13 C not correlated to carbon speciation, no vital effect on carbon pool Rotalid δ 18 O fractionation dependent on carbon speciation δ 13 C consequence of vital effect on internal carbon pool; diatom endosymbionts may benefit from increased CO 2 12 12