Assessing the effect of dissolution on planktonic foraminiferal Mg/Ca ratios:: Evidence from Caribbean core tops

In order to assess the dissolution effect on foraminiferal Mg/Ca ratios, we analyzed Mg/Ca of seven planktonic foraminiferal species and four of their varieties from Caribbean core tops from similar to 900-4700 m water depth. Depending on the foraminiferal species and variety, Mg/Ca start to decline linearly below Delta[CO32-] levels of similar to 18-26 mmol/kg by similar to 0.04-0.11 mmol mol per 1 mu mol/ kg Delta[CO32-], similar to decreases of similar to 0.5-0.8 mmol/mol per kilometer below similar to 2500-3000 m water depth. Above these species-specific critical levels, Mg/Ca remains stable with higher intraspecific Mg/Ca variability than below. We developed routines to correct Mg/Ca from below these critical thresholds for dissolution effects, which reduce the overall intraspecific variability by similar to 24-64%, and provide dissolution-corrected Mg/Ca appropriate to calculate Holocene paleotemperatures. When taking into account only dissolution-unaffected Mg/Ca from <2000 m, the systematic succession of foraminiferal species according to their Mg/Ca reflects expected calcification depths.