Effect of ocean acidification on the benthic foraminifera <i>Ammonia</i> sp. is caused by a decrease in carbonate ion concentration

Abstract

Abstract. About 30 % of the anthropogenically released CO 2 is taken up by the oceans; such uptake causes surface ocean pH to decrease and is commonly referred to as ocean acidification (OA). Foraminifera are one of the most abundant groups of marine calcifiers, estimated to precipitate ca. 50 % of biogenic calcium carbonate in the open oceans. We have compiled the state of the art literature on OA effects on foraminifera, because the majority of OA research on this group was published within the last three years. Disparate responses of this important group of marine calcifiers to OA were reported, highlighting the importance of a process-based understanding of OA effects on foraminifera. We cultured the benthic foraminifer Ammonia sp. under a range of carbonate chemistry manipulation treatments to identify the parameter of the carbonate system causing the observed effects. This parameter identification is the first step towards a process-based understanding. We argue that ] is the parameter affecting foraminiferal sizenormalized weights (SNWs) and growth rates. Based on the presented data, we can confirm the strong potential of Ammonia sp. foraminiferal SNW as a [CO 2− 3 ] proxy.

Reconsidering the role of carbonate ion concentration in calcification by marine organisms

“…9 and 12). This is illustrated with data from three publications where the influence of different carbonate-chemistry parameters on calcification rates was disentangled (Schneider and Erez, 2006;Gazeau et al, 2011;Keul et al, 2013;Fig. 2).…”

“…Panels (c, d): size-normalized weight (SNW) of the foraminifer Ammonia sp. in its asexually reproducing life cycle stage (Keul et al, 2013). Black dots: constant DIC, variable CO 2 .…”

“…HCO − 3 is dominant and has a relatively stable concentration in this entire pH range, while [CO 2− 3 ] is highly variable. In the habitat of a temperate coralline alga, for example, typical diurnal pH fluctuations can range from ∼ 8.4 at day to ∼ 7.6 at night (Cornwall et al, 2013 de Putron et al, 2011;Gazeau et al, 2011;Keul et al, 2013;Waldbusser et al, 2014 Eqs. 9 and 12).…”

“…All three studies conclude that [CO 2− 3 ] determines calcification rates although calcification rates or calcification related measurements of the hermatypic coral Acropora eurystoma (Schneider and Erez, 2006), the benthic foraminifer Ammonia sp. (Keul et al, 2013), and larvae of the Pacific oyster Crassostrea gigas (Gazeau et al, 2011) an inhibitor (Bach et al, 2011(Bach et al, , 2013(Bach et al, , 2015Jokiel, 2011aJokiel, , b, 2013Jokiel et al, 2014 (Bach et al, 2015). Indeed, HCO − 3 uptake is a common mechanism to buffer acidosis and might be facilitated at higher HCO − 3 availability (Boron, 2004;Melzner et al, 2009;Stumpp et al, 2012).…”

“…Several physiological studies with different calcifying taxa have addressed these questions by setting up experiments where the influence of individual carbonate system parameters could be studied in isolation. Some of these studies found the best correlations of calcification rates with [CO 2− 3 ] and CaCO 3 (e.g., Schneider and Erez, 2006;Gazeau et al, 2011;de Putron et al, 2011;Keul et al, 2013;Waldbusser et al, 2014), while others highlighted the importance of [HCO − 3 ] (e.g., Buitenhuis et al, 1999;Jury et al, 2010). Still others found that the response is not controlled by a single carbonate system parameter, but by the interplay of two or more.…”