Temperature effects on the shell growth of a larger benthic foraminifer (Sorites orbiculus): Results from culture experiments and micro X-ray computed tomography

Decrease in volume and density of foraminiferal shells with progressing ocean acidification

“…Temperature also will increase with p CO 2 , and all LBFs showed reduced calcification and photosymbiont health under long-term high temperatures, referred to as 2100 in the RCP8.5 scenario 7 , 21 , 22 . The shell weight of Sorites LBF decreased by 45.3% when pH decreased from control to pH 7.7 (Table 1 ), and by 28.3% when water temperature increased from 25 to 29 °C 11 . Under the RCP8.5 scenario, ocean acidification and warming will have a significant impact on reef foraminiferal carbonate production (43 million tons of current carbonate production per year 47 ) by the end of this century, even in the tropics, which is considered to be the least sensitive region in the global oceans because of its higher Ω that results from higher temperatures in that region.…”

“…1 ). Kinoshita et al 11 cultured clonal juvenile individuals of Sorites orbiculus , which belong to the same subfamily as Amphisorus , under six different temperatures (19–29 °C). MicroCT measurements showed that the shell weight and volume increased with temperature up to ~ 25 °C, whereas the density remained unchanged from pre-culturing (Fig.…”

“…Although several studies on shell density have been reported 8 , 9 , it remains unclear whether the change in shell weight in foraminifera of the same size reflects shell volume, shell density, or both, because it is difficult to measure their small shell volumes. The recently established micro X-ray computed tomography (microCT) technique enables direct and precise measurement of foraminiferal shell volume (i.e., density) with a resolution of less than 1 µm 10 , 11 . Therefore, microCT measurements can provide more precise information about foraminifera shell dimensions.…”

“…This species is common in shallow lagoon environments and accounts for 10% of the inorganic carbon production of protected lagoon communities 12 , 16 . Kinoshita et al 11 cultured the LBF Sorites orbiculus at different water temperatures and found that shell weight and volume increased with temperature, while density remained constant. However, the effect of pH on shell volume and density is not yet known.…”

Unexpected increase in structural integrity caused by thermally induced dwarfism in large benthic foraminifera

“…Plasticity in response to variability in environmental conditions or related to adaption is often expressed morphologically in foraminifers [15]. For example, in symbiont-bearing benthic foraminifera, low light levels may cause calcification of thinner shell walls that allow better penetration of light to their symbionts [16], while thermal stress results in smaller and thinner shells [4,[17][18][19]. In contrast to calcification and carbonate productivity, very little is known about the impacts of warming on the material properties that control the strength of the shell and its ability to protect the organism.…”