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

J M Bernhard,M Jeglinski,H L Filipsson,F Mezzo,J C Wit,A Mcintyre-Wressnig,W G Phalen

doi:10.5194/bg-12-5515-2015

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.

Highlights

Biomineralized carbonate of marine organisms such as foraminifera, coccolithophores, and ostracods has provided an abundance of geochemical data critical to our understanding of modern-day oceanographic conditions and processes as well as critical to reconstructions of paleoceanographic conditions and processes
Incorporation of calcein into newly precipitated carbonate was confirmed by confocal laser scanning microscope (CLSM) of bleached valves (Fig. 2g)
Because the system used during bivalve incubations was recirculating or lacking flow, it is important to consider the maximum concentration of calcein possible if all contents of the osmotic pump were dispensed into the seawater

Summary

Introduction

Biomineralized carbonate of marine organisms such as foraminifera, coccolithophores, and ostracods has provided an abundance of geochemical data critical to our understanding of modern-day oceanographic conditions and processes as well as critical to reconstructions of paleoceanographic conditions and processes. Culturing studies have contributed greatly to our understanding of the mechanisms controlling these geochemical processes during biomineralization. A variety of factors complicate proxy interpretations; the most common ones in this context include “microhabitat preferences”, “vital effects”, and rapid changes in carbonate chemistry occurring in the uppermost sediment column. Vital effects, which can include ontogenetic differences (Filipsson et al, 2010; McCorkle et al, 2008), are physiological processes that impact test geochemistry, al-

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