C ONTRIBUTION OF BENTHIC FORAMINIFERAL CULTURE
EXPERIMENTS TO PALAEOCEANOGRAPHIC PROXY CALIBRATIONS
CONTRIBUTION DE LA CULTURE DES FORAMINIFÈRES BENTHIQUES À LA CALIBRATION DE PROXIES PALÉOCÉANOGRAPHIQUES
(1) (1) (1,2) (1,*) (3) (3) (4,5) (6)
C. BARRAS , E. GESLIN , M. MOJTAHID , P. DIZ , J.-C. DUPLESSY , E. MICHEL , G.-J. REICHART , Y. ROSENTHAL ,
(2) (2) (1)
A. GOODAY , M. ZUBKOV , F. JORISSEN .
(1) LPGN-BIAF UMR6112 - Laboratoire des Bio-Indicateurs Actuels et Fossiles (BIAF), Angers, France; (2) National Oceanography Centre, Southampton, University of Southampton Waterfront Campus, European Way, Southampton, SO14 3ZH, UK; (3) LSCE- Laboratoire des Sciences du Climat et de l'Environnement, Gif- sur-Yvette, France; (4) Faculty of Geosciences, Earth Science Department, Utrecht, Netherlands; (5) Alfred Wegener Institut for Polar and Marine Research, BioGeoScience, Bremerhaven, German; (6) Institute for Marine and Coastal Sciences, Rutgers University, USA; * Currently: Departamento Geociencias Marinas y
Ordenación del Territorio, Facultad de Ciencias del Mar, Universidad de Vigo, 36310 Vigo, Spain.
1818 δO- δO (‰)f w
At 10.2°C:
(R² = 0.3956; p = 0.003)
y = 0.0012x + 0.9745
At 12.7°C:
(R² = 0.7113; p = 0.001)
y = 0.0022x + 0.2655
At 14.7°C:
(R² = 0.5695; p = 0.005)
y = 0.0017x - 0.0588
Shell size (µm) 0.00
0.20 0.40 0.60 0.80 1.00 1.20 1.40
100 120 140 160 180 200 220 240 260 280 300
18 18
δ O - δ O (‰)f w
4 6 8 10 12 14 16 18 20
-1 -0.5 0 0.5 1 1.5 2 2.5
Temperature (°C)
Kim and O’Neil (1997) B. marginata 150-200 µm B. marginata 200-250 µm
B. marginata <150 µm
Species: Bulimina marginata Type: Deep sea (500 m)
Effect of: Temperature and shell size
Scale: 4 to 19°C Effect on: δ18O
Fig. 1: Shell size effect on cultured foraminiferal shells δ18O
Fig. 2: Effect of temperature on the δ18O composition, for inorganic calcite (Kim and O’Neil, 1997) and for cultured B. marginata.
Experiments were performed at 10 different temperatures between 4 and 19°C, at which reproduction and growth of
specimens of Bulimina marginata were obtained. Oxygen isotopic composition of foraminifera entirely calcified in controlled
conditions were measured according to shell size and temperature with ICP-MS.
Calibration of δ
18O of cultured benthic foraminiferal calcite as a function of temperature (Barras et al., 2010)
• Effect of shell size on δ18O of B.
marginata: 0.001–0.002‰ μm−1 (Fig.1) Should not be neglected in
palaeoceanographic studies
• Effect of temperature on of marginata: -0.22‰ °C (Fig.2)
Similar to inorganic calcite
δ18O B.
−1
• Biological effects are negligible compared to equilibrium calcite as defined by Kim and O’Neil (1997)
Calibration of Mg/Ca of cultured Hyalinea balthica shells as a function of temperature (Rosenthal et al., 2011)
Species: Hyalinea balthica Type: Deep sea (500 m)
Effect of: temperature Scale: 8 to 13°C
Effect on: Mg/Ca Experiments were performed at 8, 10 and 13°C under stable
physico-chemical conditions, in order to study the influence of temperature on the Mg/Ca ratio of newly formed chambers of Hyalinea balthica. The Calcein tagging method was used to
identify chambers that were calcified under our controlled conditions. The composition of these chambers was analysed using laser ablation ICP-MS.
7 8 9 10 11 12 13
Temperature °C
3 4 5 6 7 8 9
Mg/Ca (mmol/mol)
Culture data and regression Core tops regression
95% Cl
Mg/Ca = 0.413T + 0.645
R² = 0.465 • Effect of temperature on Mg/Ca of
H. balthica: 0.41 mmol/mol °C (Fig. 3)−1
Sensitivity ~4 times higher than observed in other benthic foraminifera
• Calibration obtained with cultured specimens is very similar to the core tops calibration (Fig. 3, dashed blue line)
Scatter in Mg/Ca measurements both within a single specimen and among
different shells calcified under identical conditions
• Fig. 3: Calibration of cultured H. balthica shells
obtained by multiple LA-ICP-MS analyses of individual specimens.
Effect of salinity and ontogeny on isotopic and trace metal composition of Ammonia tepida (Diz et al., 2012)
Species: Ammonia tepida Type: Coastal
Effect of: Salinity and shell size
Scale: 29.8 to 35.5‰
Effect on: δ18O, Mg/Ca, Sr/Ca
The aim of these experiments was to study the effect of
salinity (29.8, 32.2, 35.5) on the geochemical composition (trace metals and isotopes) of cultured Ammonia tepida shells entirely calcified in controlled conditions.
<150 150-200 200-250 250-300 300-350 350-400 400-450 450-500 500-550 550-600 600-650 650-700 700-750
1 1.2 1.4 1.6 1.8 2 2.2
Size Interval (µm)
Sr/Ca (mmol/mol)
Fig. 4: Example of shell size effect on Sr/Ca incorporation in cultured A. tepida at 35.5 salinity.
Shell size effect:
• Not significant for Mg/Ca and δ18O
• Significant for Sr/Ca (Fig.4)
Fig. 5: Effect of salinity on a) Mg/Ca, b) Sr/Ca, and c) δ18O of cultured A.
tepida.
• Not significant for Mg/Ca and Sr/Ca
Mg/Ca can be used for temperature
reconstructions
Large inter-shell variability should be taken into account
• Variations in foraminiferal δ18O correlated with
variations in seawater δ18O
Salinity
25 30 35 40
0.5 1 1.5 2 2.5 3
Mg/Ca (mmol/mol)
25 30 35 40
Salinity
0.8 1.2 1.6 2 2.4
Sr/Ca (mmol/mol)
-1.5 -1 -0.5
0 0.5 1
18 δO ‰ VPDB
25 30 35 40
Salinity
A. beccarii
H. germanica
Linking foraminiferal diets and shell chemistry: an experimental approach (Mojtahid et al., 2011)
Species: Ammonia tepida
Haynesina germanica
Type: Coastal Effect of: Diet
Food: Labelled bacteria ( H 3
and C)14
Effect on: δ13C
DNA
RNA and Protein Nucleoplasme
Cytoplasm
mRNA
ATP
14CO2= 62 %
Filter
3H= 0.4 %
14C = 0.6 %
Water
AssimilationDigestion
Respiration (estimated)
14C = 0.1 %
3H= 23 %
14C = 26 %
3H= 63 %
14C = 12 %
Evaporation ??
ASW
After 15-20 days
6 ml scintillation
cocktail
200 µL
GF/B Filter
Gas tight glass vial
NaOH (5 M)
HCL (10%)
needle 0.8 mm needle
0.6 mm
Gas tight glass vial
24 h
1.8 mL scintillation cocktail
1.8 mL scintillation cocktail Control
Other protozoa
Calcareous foraminifera
24 hrs
Scintillation counter
24 hrs 24 hrs
24 h
80
0 20 40 60
0 20 40 60 80
1 3 5 7 9 11 13 15 17
3 H Label, % of initial stock
14 C Label, % of initial stock
Haynesina germanica Ammonia beccarii
Days
19
Control: only bacteria Uronema sp.
A. beccarii
Pteridomonas sp.
50 µl
Scintillation vial 6 ml scintillation
cocktail
24 hrs Scintillation counter Daily sampling
15-20 days
24 h
H. germanica Psammophaga sp.
50 ml 40 ml
30 ml 20 ml
10 ml 50 ml
40 ml 30 ml 20 ml 10 ml 3H-Leucine
7.0 10 mol/l-6
14C-Leucine 1.6 10 mol/l-4
30 min Pump
50 ml 40 ml 30 ml 20 ml 10 ml Cold
Leucine 3.2 10 mol/l-3
1-2 hrs
Microwave oven 7 blasts of 10 sec
Water
2-4 ml
0.4 μm collagen membrane insert
47 mm GF/A filters
5 ml ASW
2 ml ASW 3 ml ASW
50 ml 40 ml 30 ml 20 ml 10 ml
Bacterial suspension
Fig. 7: Synthetic main results
figure of the Foraminifera
grazed bacteria at a rate of 3.2–5.7
−1 −1
ng C ind h
3 14
Fig. 6: H and C label release into the water
Very little of the C ingested by adult foraminifera is incorporated into the shell.
However, we cannot conclude that diet has no influence since none of our
calcareous
specimens grew new chambers.
The advantage of laboratory experiments is the possibility to control all physico-chemical parameters of the culture medium. Thereby, it becomes possible to produce paleoceanographic proxy calibrations by studying the influence of a single parameter on the geochemical composition of foraminiferal shells
entirely calcified in controlled conditions.
These studies demonstrate the value of performing proxy calibrations under laboratory controlled
conditions. We plan to persue this work by developping a new proxy of paleo-oxygenation through the regional (Pays de la Loire) research program MADONA (Micro-Analyse Des Organismes marins Nantes Angers).
LPG-BIAF/UMR 6112
