Mg isotopes in biocarbonatesMg isotopes in biocarbonates

New insights into vital effects associated New insights into vital effects associated toto

echinoderm and bivalve calcificationechinoderm and bivalve calcification

F. Planchon, J. Hermans, C. Borremans, Ph. Dubois, C. Poulain, Y.-M. Paulet and L. André

PaleoSalt

δδ2626Mg in Biocarbonates: Mg in Biocarbonates: IntroductionIntroduction

Mg/Ca tool

MgFluidCaCarbonate + MgCarbonate+CaFluid

KdMg/Ca ≈ DMg = f(T)

0

20

40

60

80

100

120

0 20 40 60 80

Mg/

Ca (m

mol

/mol

)

T (°C)

Inorganic AragoniteGae tani (2006)

Inorganic Calc iteOomor i (1987)

δδ2626Mg in Biocarbonates: Mg in Biocarbonates: IntroductionIntroduction

Mg/Ca tool

T Proxy

BioCaCO3

MgFluidCaCarbonate + MgCarbonate+CaFluid

KdMg/Ca ≈ DMg = f(T)

From Gaetani (2006), Lear (2002), Elderfield and Ganssen (2000), Mashiota (1999)

Vital Effects

MetabolismAge

Salinity, etc.

δδ2626Mg in Biocarbonates: Mg in Biocarbonates: IntroductionIntroduction

Mg/Ca tool

T Proxy

BioCaCO3

MgFluidCaCarbonate + MgCarbonate+CaFluid

Vital Effects26Mg

25Mg

24Mg

δ26MgFluid

δ26MgCarbonateΔCarbonate-Fluid

δ26MgBiocarbonate

ΔInorg-org

δ26Mg

δ25Mg

Galy (2001) MetabolismAge

Salinity, etc.

δδ2626Mg in Biocarbonates: Mg in Biocarbonates: MethodologyMethodology

Sample Purification Cationic exhange chromatography

(Chang, 2003) Full Mg recovery Clean techniques

δδ2626Mg in Biocarbonates: Mg in Biocarbonates: MethodologyMethodology

Sample Purification Cationic exhange chromatography

(Chang, 2003) Full Mg recovery Clean techniques

Analysis MC-ICP-MS (Nu instrument) Desolvation (Aridus II) High sensitivity

50-100 ng/g Standard bracketing

Relative to DSM3

0.1562

0.1564

0.1566

0.1568

0.1570

0.1572

0.1574

0.1576

0.1578

0 20 40 60 80 100 120

26Mg/24Mg

Analyses Number

-4

-3

-2

-1

0

-7 -6 -5 -4 -3 -2 -1 0

δ25Mg (‰)

δ26Mg (‰)

Seawater

Coral and Sclerosponge (Aragonite)

Coral, Sclerosponge and Red algae (Calcite)

Echinoderm (Calcite)

Brachiopod (Calcite)

Coccolith (Calcite)

Mixed Planktonic forams (Calcite)

Mixed Benthic foram (Calcite)

δδ2626Mg in Biocarbonates : Overview Mg in Biocarbonates : Overview

Chang (2003, 2004), Wombacher (2006) and Tipper (2006)

Mass-dependent fractionation line

δδ2626Mg in Biocarbonates: SamplesMg in Biocarbonates: Samples

Echinoderms Starfish Sea Urchin

Morphology Culture Exp (T, S)

Bivalves Clams (Ruditapes Ph.) Salinity Gradient (2 sites)

Auray River Shell Internal fluids Soft tissus

EchinodermsEchinoderms

Sea urchin and starfish

-4

-3

-2

-1

0

-7 -6 -5 -4 -3 -2 -1 0

δ25Mg (‰)

δ26Mg (‰)

Seawater

Coral, Sclerosponge and Red algae (Calcite)

Echinoderm (Calcite)

Brachiopod (Calcite)

Mixed Benthic foram (Calcite)

Starfish (this study)

Sea urchin (this study)

δδ2626Mg in Biocarbonates : Echinoderms (Starfish and Sea urchin) Mg in Biocarbonates : Echinoderms (Starfish and Sea urchin)

Chang (2003, 2004), Wombacher (2006) and Tipper (2006)

Planktonic Forams

Coccoliths

Inorganic Calcite (theo)

Δwater-mineral26Mg: -2.7±0.2‰

Biological effects

0.5 < ΔInorg-org26Mg < 1.5 ‰

Galy (2002)

δδ2626Mg in Biocarbonates : Sea urchinMg in Biocarbonates : Sea urchin

-3.0 -2.8 -2.6 -2.4 -2.2 -2.0

I

II

III

IV

V

Mouth

Spines

δ26Mg (‰)

Morphological variability

Interambulacral plates record

Endoskeleton characteristics

δδ2626Mg in Biocarbonates : Sea urchinMg in Biocarbonates : Sea urchin

Culture experiment (T & S control) δ26 : f(T) δ26 : f([Mg])

Proxy implication

Low metabolism impact

y = -0.024x - 1.977R² = 0.778

y = -0.035x - 1.822R² = 0.904

-3.0

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

10 12 14 16 18 20 22 24 26

δ26M

g (‰

)

T (°C)

36‰

39‰

Aq Seawater

y = -11.65x - 1.218R² = 0.685

y = -11.75x - 1.245R² = 0.723

-2.8

-2.7

-2.6

-2.5

-2.4

-2.3

-2.2

-2.1

-2.0

0.080 0.090 0.100 0.110 0.120 0.130

δ26M

g (‰

)

Mg/Ca (mol/mol)

36‰ 39‰

-2.8

-2.7

-2.6

-2.5

-2.4

-2.3

-2.2

-2.1

-2.0

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35

δ26M

g (‰

)

Growth rate (mg/d)

36‰ 39‰

δδ2626Mg in Biocarbonates : Sea urchin CalcificationMg in Biocarbonates : Sea urchin Calcification

δ26Mgseawater

-0.8 ‰

Intra-cellular Calcification

δ26MgBiocarbonate

-2.2 to -2.7 ‰

δ26Mgintracell

Metabolism

ACC

Equilibrium-like fractionation

Biological mediation

Cell membrane transport

Amorphous phase regulation

δδ2626Mg in Biocarbonates : StarfishMg in Biocarbonates : Starfish

-3.2 -3.1 -3.0 -2.9 -2.8

Asterina

Anseropoda

Marthasterias

Asterias

Echinaster

Henricia

δ26Mg (‰)

Low interspecies variability

Moderate biological control

BivalvesBivalves

Aragonitic Clams (Ruditapes philippinarum)

δδ2626Mg in Biocarbonates : Bivalves (Clams, Ruditapes philippinarum)Mg in Biocarbonates : Bivalves (Clams, Ruditapes philippinarum)

Le Bono

Locquemariaquer

Poulain (2006)

δδ2626Mg in Biocarbonates : Bivalves (Clams, Ruditapes philippinarum)Mg in Biocarbonates : Bivalves (Clams, Ruditapes philippinarum)

-5.0

-4.0

-3.0

-2.0

-1.0

0.0

Seawater Extrapaleal Hemolymph Mant. Musc. Oth. Oyster Shell Coral Clams

δ26Mg (‰)

Morbihan Gulf Auray River (Le Bono) SRM

Internal Fluids Soft Tissues Biocarbonates

Conclusions : δ26 Mg– δ25Mg in biocarbonatesConclusions : δ26 Mg– δ25Mg in biocarbonates

New tool to explore biocalcification processes Identification of mass-dependent fractionation Potential reservoirs involved

Paleoceanographic Proxy Direct relationship with T and S Constrain biocalcification model

Theoretical approach is needed System evolution (closed-open) Equilibrium – disequilibrium Complex mixing model (metabolism, energy consumption, etc.)

Thanks for your attentionThanks for your attention

δδ2626Mg in Biocarbonates : Bivalves (Clams, Ruditapes philippinarum)Mg in Biocarbonates : Bivalves (Clams, Ruditapes philippinarum)

Adapted from Carré (2006)