Mn Incorporation in Large Benthic Foraminifera: Differences Between Species and the Impact of pCO2

Abstract

Element concentrations of calcite precipitated by foraminifera reflect chemical and physical properties of seawater and can therefore be used to reconstruct (paleo-)environmental conditions. Foraminiferal carbonate associated manganese incorporation (expressed here as Mn/Ca) is a potential proxy for seawater oxygenation, although the impacts of other environmental parameters need to be quantified before Mn/Ca can be robustly applied. Here we report the isolated impact of seawater carbonate chemistry on manganese incorporation in the shells of two large symbiont-bearing benthic foraminiferal species. Moreover, we investigated the role of biomineralization on manganese incorporation by using species with contrasting calcification pathways: the hyaline species Amphistegina gibbosa and the porcelaneous species Sorites marginalis. Furthermore, analyzing shells from a wide range of species grown under identical conditions allowed assessment of species-specific Mn incorporation in other foraminiferal species. Our observations show that species specific differences in biomineralization strategies are the dominant factor determining Mn content. Shells from porcelaneous species, with relatively high Mg contents, are generally also enriched in Mn compared to low-Mg/Ca foraminifera. Superimposed on the effect of biomineralization, chemical speciation of elements in seawater as a function of pCO 2 also affects their incorporation. Whereas the impact of the carbonate system is limited, the inter-specific differences call for species specific calibrations in order to use Mn uptake as a (paleo-)oxygenation proxy.

Host-influenced geochemical signature in the parasitic foraminifera <i>Hyrrokkin sarcophaga</i>

“…The attachment etchings of foraminifera have been proposed to serve as an anchoring function and increase protection from predators and the hydrodynamic regime. Possibly, the foraminifera also dissolve the host's carbonate material to satisfy the calcium and/or DIC requirements of H. sarcophaga for the calcification of its shell (Cedhagen, 1994;Vénec-Peyré, 1996;Todd, 1965) rather than expending further energy to source Ca/DIC from the surrounding seawater (Fig. 6a).…”

The coral reef-dwelling Peneroplis spp. shows calcification recovery to ocean acidification conditions

“…Despite the large error bars, our Mn/Ca values (94.5 ± 59.9 to 173.8 ± 142.2 μmol/mol; Fig. 5 ) were in the range of concentrations observed in the high-Mg calcite LBF Sorites marginalis (61.7 ± 27.4 μmol/mol 74 ). In previous culture experiments, these three E/Ca ratios have been correlated with diverse carbonate system parameters 36 , 57 , 74 , 75 .…”

“…5 ) were in the range of concentrations observed in the high-Mg calcite LBF Sorites marginalis (61.7 ± 27.4 μmol/mol 74 ). In previous culture experiments, these three E/Ca ratios have been correlated with diverse carbonate system parameters 36 , 57 , 74 , 75 . However, in our study, the 3 days under low pH 6.9 during the decalcification phase had no visible impact on the Mg, Sr, and to a lesser extent Mn incorporation in Peneroplis spp.…”

Foraminiferal Mn/Ca as Bottom‐Water Hypoxia Proxy: An Assessment of Nonionella stella in the Santa Barbara Basin, USA

“…While both soluble Mn(II) and Mn(III) are potentially bioavailable (e.g., Madison et al, 2011;Oldham et al, 2015;Trouwborst et al, 2006), foraminifera would incorporate only Mn(II) (van Dijk et al, 2019). A recent culturing study on large benthic foraminifera hypothesized sea-water carbonate chemistry as a potential factor in Mn speciation and foraminiferal incorporation (van Dijk et al, 2020). However, the significance of this effect versus differences in pore-water [Mn] driving foraminiferal Mn/Ca remains to be determined.…”

“…The geochemical composition of foraminiferal tests is governed by both external environmental parameters (e.g., Epstein et al, 1951;Murray, 2014;Nürnberg et al, 1996;Pearson, 2012) and internal factors, such as microhabitat preferences, seasonality, ontogeny, ecology and biomineralization processes (e.g., Barras et al, 2018;Koho et al, 2017;van Dijk et al, 2019;Zeebe et al, 2008). While the empirical proxy relationship of foraminiferal Mn/Ca and ambient Mn availability is generally supported by both field and culture studies (e.g., Barras et al, 2018;Koho et al, 2017;Munsel et al, 2010), the pathways of Mn uptake and incorporation to the site of calcification during biomineralization, specifically remain a topic of active discussion (e.g., Barras et al, 2018;van Dijk et al, 2019van Dijk et al, , 2020. Difficulties in reaching a consensus between putative biomineralization models might partly be related to species-specific controls on calcification processes (e.g., de Nooijer et al, 2014), making an accurate identification of taxa essential for the reliable application of proxies.…”