Technical Note: Towards resolving in situ, centimeter-scale location and timing of biomineralization in calcareous meiobenthos – the calcein–osmotic pump method

Abstract

Abstract. Insights into oceanographic environmental conditions such as paleoproductivity, deep-water temperatures, salinity, ice volumes, and nutrient cycling have all been obtained from geochemical analyses of biomineralized carbonate of marine organisms. However, we cannot fully understand geochemical proxy incorporation and the fidelity of such in species until we better understand fundamental aspects of their ecology such as where and when these (micro)organisms calcify. Here, we present an innovative method using osmotic pumps and the fluorescent marker calcein to help identify where and when calcareous meiofauna calcify in situ. Method development initially involved juvenile quahogs (Mercenaria mercenaria); subsequent method refinement involved a neritic benthic foraminiferal community. Future applications of this method will allow determining the in situ growth rate in calcareous organisms and provide insights about microhabitats where paleoceanographically relevant benthic foraminifera actually calcify.

Foraminiferal Ultrastructure: A perspective From Fluorescent and Fluorogenic Probes

“…Calcein ( Bis(N , N‐bis (carboxymethyl)aminomethyl)‐fluorescein ) is used to label and distinguish newly grown chambers (Bernhard et al, ), allowing the determination of growth and reproduction under controlled laboratory conditions (e.g., Diz et al, ; Hintz et al, ). Calcein was also used to check the incorporation of trace elements to the new chambers (e.g., de Nooijer et al, ; Evans et al, ; Kramar et al, ; Munsel et al, ; Nardelli et al, ; Van Dijk, de Nooijer, Wolthers, et al, ; van Dijk, de Nooijer, & Reichart, ), to assess the role of fluid‐phase endocytosis in calcification (Bentov et al, ) and in sediment samples to develop a method that can identify the location and timing of calcification (Bernhard et al, ). Possible impacts of calcein were evaluated by Bernhard et al (), Dissard et al (), and Kurtarkar et al (), who found that the marker does not affect the survival rate of individuals, incorporation of elements, nor their growth rates.…”

Calcein Staining as a Tool to Investigate Coccolithophore Calcification

“…However, few studies have utilized calcein to study calcification in protists. One notable exception are the foraminifera, in which calcein serves as a valuable non-toxic probe used to discriminate pre-existing and newly formed calcite chambers, understand various processes associated with shell production, examine ontogenetic variations, facilitate validation of biomineral proxies, and detect meifaunal calcifiers in situ (Bernhard et al, 2004(Bernhard et al, , 2015Bentov et al, 2009;Dissard et al, 2009;Kurtarkar et al, 2015).…”