Remineralisation of organic particles in the presence of ballast minerals
In the deep ocean, fluxes of particulate organic carbon (POC) and calcium carbonate are positively correlated, suggesting that CaCO3 may increase the density of sinking particles and/or protect organic matter from degradation by prokaryotes, the so-called "ballast effect".
We showed that calcifying aggregates were more sensitive to degradation with increasing hydrostatic pressure than previously thought. Increased hydrostatic pressure also had a positive effect on particle aggregation, which may offset the effect of increased cell lysis.
Our results imply that in coccolithophorid-dominated sedimentation aggregates, the ballasting and protective effects of coccoliths may collapse throughout the water column. The increased aggregation potential with pressure observed under these controlled conditions may, to some extent, compensate for the loss of mineral ballast, although this needs to be confirmed in situ.
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