Ocean acidification induces biochemical and morphological changes in the calcification process of large benthic foraminifera

Abstract

Large benthic foraminifera are significant contributors to sediment formation on coral reefs, yet they are vulnerable to ocean acidification. Here, we assessed the biochemical and morphological impacts of acidification on the calcification of Amphistegina lessonii and Marginopora vertebralis exposed to different pH conditions. We measured growth rates (surface area and buoyant weight) and Ca-ATPase and Mg-ATPase activities and calculated shell density using micro-computer tomography images. In A. lessonii, we detected a significant decrease in buoyant weight, a reduction in the density of inner skeletal chambers, and an increase of Ca-ATPase and Mg-ATPase activities at pH 7.6 when compared with ambient conditions of pH 8.1. By contrast, M. vertebralis showed an inhibition in Mg-ATPase activity under lowered pH, with growth rate and skeletal density remaining constant. While M. vertebralis is considered to be more sensitive than A. lessonii owing to its high-Mg-calcite skeleton, it appears to be less affected by changes in pH, based on the parameters assessed in this study. We suggest difference in biochemical pathways of calcification as the main factor influencing response to changes in pH levels, and that A. lessonii and M. vertebralis have the ability to regulate biochemical functions to cope with short-term increases in acidity.

Effects of Elevated Temperature on the Shell Density of the Large Benthic Foraminifera Amphistegina lobifera

“…(), and modified by Prazeres et al. (). Individuals were cleaned using a fine brush, washed in de‐ionized water and oven‐dried at 37 °C at the end of the experiment.…”

“…The existence of enzymes capable of transporting Mg 2+ ions within the cell of foraminifera was uncertain until recently, but was successfully detected in two species of LBF, Amphistegina lessonii and Marginopora vertebralis (Prazeres et al. ). Its role in the calcification of foraminifera is still unclear (Prazeres et al.…”

“…Its role in the calcification of foraminifera is still unclear (Prazeres et al. ; Zeebe and Sanyal ), but may be responsible for depressing the Mg 2+ content of the calcification fluid (Allison et al. ).…”

Test flattening in the larger foraminifer Heterostegina depressa: predicting bathymetry from axial sections

“…Additionally, nummulitids in particular have been distinguished as highly informative facies fossils (Hallock and Glenn 1986;Beavington-Penney and Racey 2004). These inferences on the ecology of fossil nummulitids were possible due to thorough actuopaleontological research on the intricate ecological constraints of larger benthic foraminiferal test morphology (Reiss and Hottinger 1984;Hallock et al , 1991Hottinger 2000;Hohenegger 2009Hohenegger , 2011aPrazeres et al 2015;Eder et al 2017a). Their shape and function is strongly influenced by two major factors: first, the intrinsic need to provide and shelter their symbionts, developing so-called microscopic greenhouses (sensu Hohenegger 2011b); and second, the need to adapt to physical factors of their immediate environment, mainly light attenuation and hydrodynamic energy (Hottinger 2000;Hohenegger 2004;Briguglio and Hohenegger 2009;Seddighi et al 2015).…”

Morphological variations in Cycloclypeus carpenteri: Multiple embryos and multiple equatorial layers

“…A detailed observation of the entire internal structure of an LBF is very important to investigate those specimens affected by teratologies (Ferrandez-Cañadell et al, 2014), complex sub-surface structures (Renema and Cotton, 2015) or to quantify complex characters such as dissolution (Johnstone et al, 2011), shell density (Prazeres et al, 2015) or chamber volume .…”