Effect of trace metal availability on coccolithophorid calcification

Area of Science:

• Oceanography
• Marine Biogeochemistry
• Paleoclimatology

Background:

• Oceanic dust deposition varies over geological time.
• Trace metals from dust, like iron and zinc, are vital phytoplankton nutrients.
• Dust supply variations may impact ocean primary production and carbon cycling.

Purpose of the Study:

• Investigate the influence of iron and zinc on Emiliania huxleyi.
• Determine how trace metal limitation affects biogenic calcification.
• Understand the impact of dust deposition on the ocean's biological carbon pump.

Main Methods:

• Cultured the marine microalga Emiliania huxleyi under varying iron and zinc concentrations.
• Measured growth rates and calcium carbonate (CaCO3) production.
• Analyzed the ratio of particulate organic carbon to CaCO3 export (rain ratio).

Main Results:

• Low iron reduced both growth and calcification in Emiliania huxleyi.
• Low zinc decoupled growth from calcification, leading to more calcified cells.
• Zinc-limited cells showed unaffected CaCO3 production rates per cell despite slower growth.

Conclusions:

• Trace metal availability, particularly zinc, significantly influences biogenic calcification.
• Changes in dust deposition can alter calcification in trace metal-limited ocean regions.
• Variations in calcification may affect oceanic CO2 sequestration and atmospheric partitioning.