Journal of Marine Science: Research & Development
Open Access

Abstract

Increased CO 2 emissions into the atmosphere lead to increased concentration of dissolved CO 2 in the ocean. Chemical reactions between the dissolved CO 2 and seawater transform the dissolved CO 2 into HCO 3- and CO 2- and produce H+ ions. These ions increase the acidity of seawater and decrease pH. Increased acidity and decreased availability of calcium and magnesium ions affect carbonate and aragonite production by marine calcifiers in the Pacific Ocean. Large benthic foraminifera, such as Marginopora vertebralis Quoy and Gaimard, 1830, produce calcite with high magnesium (Mg) content and have an important role in sand building on Pacific Islands. It is thus important to better understand the biomineralization processes in foraminifers for predicting their calcification response to ocean acidification. To assess the response of benthic foraminifer to changing carbondioxide levels,we cultured Marginopora vertebralis Quoy and Gaimard, 1830 at three different pH levels (pH 7.5,pH 7.8 and pH 8.1(ambient seawater).The fluorescent compound calcein ( 40 micromoles/litre) was added to the culturing tanks to mark the calcite growth during the culturing period. The specimen grown in the laboratory were analysed using laser ablation- inductively coupled plasma mass spectroscopy (LA-ICPMS) and electron probe micro analyser (EPMA) to measure elemental compositions and (B/Ca, Mg/Ca and Sr/Ca) ratios. Results indicate that the shell weight decreased with decreasing pH level. The elemental ratios also decreased with decreasing pH.

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