Seawater carbonate chemistry, productivity and calcification of Marginopora vertebralis in a laboratory experiment, supplement to: Uthicke, Sven; Fabricius, Katharina Elisabeth (2012): Productivity gains do not compensate for reduced calcification under near-future ocean acidification in the photosynthetic benthic foraminifer species Marginopora vertebralis. Global Change Biology, 18(9), 2781-2791


Changes in the seawater carbonate chemistry (ocean acidification) from increasing atmospheric carbon dioxide (CO2 ) concentrations negatively affect many marine calcifying organisms, but may benefit primary producers under dissolved inorganic carbon (DIC) limitation. To improve predictions of the ecological effects of ocean acidification, the net gains and losses between the processes of photosynthesis and calcification need to be studied jointly on physiological and population levels. We studied productivity, respiration, and abundances of the symbiont-bearing foraminifer species Marginopora vertebralis on natural CO2 seeps in Papua New Guinea and conducted additional studies on production and calcification on the Great Barrier Reef (GBR) using artificially enhanced pCO2 . Net oxygen production increased up to 90% with increasing pCO2 ; temperature, light, and pH together explaining 61% of the variance in production. Production increased with increasing light and increasing pCO2 and declined at higher temperatures. Respiration was also significantly elevated (~25%), whereas calcification was reduced (16-39%) at low pH/high pCO2 compared to present-day conditions. In the field, M. vertebralis was absent at three CO2 seep sites at pHTotal levels below ~7.9 (pCO2 ~700 µatm), but it was found in densities of over 1000 m(-2) at all three control sites. The study showed that endosymbiotic algae in foraminifera benefit from increased DIC availability and may be naturally carbon limited. The observed reduction in calcification may have been caused either by increased energy demands for proton pumping (measured as elevated rates of respiration) or by stronger competition for DIC from the more productive symbionts. The net outcome of these two competing processes is that M. vertebralis cannot maintain populations under pCO2 exceeding 700 µatm, thus are likely to be extinct in the next century.

Metadata Access
Creator Fabricius, Katharina Elisabeth;Uthicke, Sven
Publisher PANGAEA - Data Publisher for Earth & Environmental Science
Publication Year 2012
Rights Creative Commons Attribution 3.0 Unported (CC-BY)
Language English
Resource Type Supplementary Dataset
Format text/tab-separated-values
Discipline Earth System Research
Spatial Coverage (19S-10S,146E-151E)
Temporal Point 2011-04-01T11:59:59Z