Effect of different seawater Mg concentrations on calcification in two benthic foraminifers.

Magnesium, incorporated in foraminiferal calcite (Mg/Ca), is used intensively to reconstruct past seawater temperatures but, in addition to temperature, the Mg/Ca of foraminiferal tests also depends on the ratio of Mg and Ca in seawater (Mg/Ca). The physiological mechanisms responsible for these proxy relationships are still unknown. This culture study investigates the impact of different seawater [Mg] on calcification in two benthic foraminiferal species precipitating contrasting Mg/Ca: , producing low-Mg calcite and , producing intermediate-Mg calcite.

Unexpected biotic resilience on the Japanese seafloor caused by the 2011 Tōhoku-Oki tsunami.

On March 11(th), 2011 the Mw 9.0 2011 Tōhoku-Oki earthquake resulted in a tsunami which caused major devastation in coastal areas. Along the Japanese NE coast, tsunami waves reached maximum run-ups of 40 m, and travelled kilometers inland.

Foraminifera promote calcification by elevating their intracellular pH.

Surface seawaters are supersaturated with respect to calcite, but high concentrations of magnesium prevent spontaneous nucleation and growth of crystals. Foraminifera are the most widespread group of calcifying organisms and generally produce calcite with a low Mg content, indicating that they actively remove Mg(2+) from vacuolized seawater before calcite precipitation. However, one order of foraminifera has evolved a calcification pathway, by which it produces calcite with a very high Mg content, suggesting that these species do not alter the Mg/Ca ratio of vacuolized seawater considerably.