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PALEOSALT 2008 Bivalves - VUB. Rémy Mas, Fabrice Servaes, Maité Bauwens, Céline Poulain, Philippe Claeys, Eddy Keppens, Frank Dehairs. Objectives. Understanding impact of external controls (environmental conditions) on Trace Elements and Isotopes incorporation in bivalve shells
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PALEOSALT 2008Bivalves - VUB Rémy Mas, Fabrice Servaes, Maité Bauwens, Céline Poulain, Philippe Claeys, Eddy Keppens, Frank Dehairs
Objectives • Understanding impact of external controls (environmental conditions) on Trace Elements and Isotopes incorporation in bivalve shells Aquarium experiment • Development of the δD salinity proxy applied to organic matter in bivalve shells In situ work : Scheldt estuary and Auray river
Aquarium Experiments 1 • Sampling • 05 Feb 07 • Mytilus edulis • knokke • Acclimation • Same temperature and salinity as used for experiment • Experiment • Start 19 Feb 07 • End 30 April 07 Knokke
Juvenile S1 F2 T1 S2 F2 F1 S1 F2 T2 F1 S2 F2 T1 S2 F2 Adult Aquarium Experiments 2 • - Food : Tetracelmis suecica; δ13C=-30‰ • F1=8mgDW/week/org. • F2=16mgDW/week/org. • - Age : Juvenile (<1year) Vs ‘Adult’ (~1 year old) • Temperature • T18°C ; T216°C • Salinity • S228 (sea water) δ18Omean = -0.31 ‰ δ13CDIC = -0,36 ‰ • S118 (diluted water) δ18Omean = -2.85 ‰ δ13CDIC = -0,37 ‰
Temperature ∆L Salinity ∆L Difference statistically very significant Difference statistically significant Difference statistically not significant Aquarium Experiments 3 • Growing (∆L of the shell)
Difference statistically very significant Difference statistically significant Difference statistically not significant Aquarium Experiments 4 • N isotopic composition of mussel tissues • C isotopic composition of mussel tissues
Aquarium Experiments 5 • Carbonate • Sampling with microdrilling 300μm 800μm Drill line 1cm
T1=8°C S2=28 δ180w = -0.31 Wanamaker et al. 2007 T(°C)=16.19-4.69*(δ18Os-δ18Ow)+0.17(δ18Os-δ18Ow)² Adult Adulte δ18Os = 1.20 Tcalc= 9.5 Juvenile Juvenile δ18Os =1.07 Tcalc = 10.0
T2=16°C S2=28 δ18Ow = -0.31 T2S2F2 δ18Os = -0.23 Tcalc = 15.8 T2S2F1 δ18Os = -0.54 Tcalc = 17.3
Problem T2=16°C S1=18 δ18Ow = -2.85 T2S1F2 δ18Os = -0.17 Tcalc = 4.8 T2S1F1 δ18Os = -0.33 Tcalc = 5.5
Aquarium Experiments 6 • Trace Elements (Ba, Sr, Mg, Mn…) • New machine : laser UP193FX(Fast excimer) Merchantec 193nm. coupled to a ICP-MS Thermo X series 2. (Summer 2008)
Scheldt & Auray 1 Ruditapes philippinarum • Sampling BONO OS KN HF 10 km GR LOCMARIAQUER Mytilus edulis 1 km
Scheldt & Auray 3 • δ13C & δ15N from bivalves • Tissues • Shell OM Sea Mytilus edulis Shell organic matrix Ruditapes philippinarum Shell organic matrix Sea
Scheldt & Auray 4 • Lipids • GC-MS • Extraction of total lipids (modified Bligh & Dyer extraction) from bulk shell (without decarbonatation) • Derivatization : Silylation BSTFA 60°C, 30min • Method GC : • Column : DB-5 30m, Ø 0.25mm • 50°C (2min) 300°C (15min) 4°C/min
Mytilus edulis Ruditapes
Me 038 KN Mytilus edulis Fatty acids 19:0 21:0 17:0 Sterols 18:0 15:0 20:0 19:1
Scheldt & Auray 5 In the near future : • GC-MS • Precise identification • Quantitative measurement • GC-IRMS • δ13C measurements • Comparison of δ13C of specific compounds with estuarine gradient
Perspectives • Improvement of Mollusk shell Lipidsextraction : Collaboration project with B. Farre; University Paris Sud; BIOCALC project; EUROCORES Program • Deuterium analyses on specific lipidic compounds in collaboration with Dr. Stefan Schouten, Royal NIOZ
17.56 35.06 18.83 25.85 22.58 37.49 39.19 28.43
39.86 54.32 43.59 55.48 60.52 44.22 64.69 46.49
Difference statistically very significant Difference statistically significant Difference statistically not significant Aquarium Experiments • Tissue Dry Weight after the end of the experiment Difference before experiment