Data from: Efficient carbon recycling between calcification and photosynthesis in red coralline algae

Red coralline algae create abundant, spatially vast, reef ecosystems
throughout our coastal oceans with significant ecosystem service
provision, but our understanding of their basic physiology is lacking. In
particular, the balance and linkages between carbon-producing and
carbon-sequestering processes remain poorly constrained, with significant
implications understanding their role in carbon sequestration and storage.
Using a dual radioisotope tracing, we provide evidence for coupling
between photosynthesis (which requires CO2) and calcification (which
releases CO2) in the red coralline alga Boreolithothamnion soriferum
(previously Lithothamnion soriferum) – a marine ecosystem engineer widely
distributed across Atlantic mid-high latitudes. Of the sequestered HCO3-,
38±22% was deposited as carbonate skeleton whilst 39±14% was incorporated
into organic matter via photosynthesis. Only 38±2% of the sequestered
HCO3- was transformed into CO2, and almost 40% of that was internally
recycled as photosynthetic substrate, reducing the net release of carbon
to 23±3% of the total uptake. Calcification rate was strongly dependent on
photosynthetic substrate production, supporting the presence of
photosynthetically-enhanced calcification. The efficient carbon-recycling
physiology reported here suggests that calcifying algae may not be as
important in marine system CO2 release as is currently assumed, supporting
a reassessment of their role in blue carbon accounting.