Coccolithophores at the continental margin: Biogeochemical aspects - PowerPoint PPT Presentation

Coccolithophores at the continental margin: Biogeochemical aspects of bloom formation and development Jérôme Harlay

������������� Anja Engel, Judith Piontek, Corinna Borchard, Nicole Händel, AWI Lei Chou, Caroline De Bodt, Nathalie Roevros, ULB Alberto Borges, Bruno Delille, Kim Suykens, ULg Koen Sabbe, Nicolas Van Oostende, UGent Steve Groom, PML ROLE OF PELAGIC CALCIFICATION AND EXPORT OF CARBONATE PRODUCTION IN CLIMATE CHANGE funded by the Belgian Federal Science Policy Office Science for a Sustainable Development - Climate and Atmosphere CONTRAT N°SD/CS/03A / B

������� ������� • Preambule: – Problematic of coccolithophorid studies – Internal calcification – Lessons from the cultures – Ecological niche • Results: – Bay of Biscay – Multidisciplinary cruises – 2004 – 2006 – 2008 • Perspectives: – Synthesis of field data – Mechanism of bloom development in the Bay of Biscay – Conceptual model for coccolithophorid calcification

������������ ������������ Coccolithophores play a major role in the biogeochemical cycle of the world ocean: - Primary producers: ( ) ( ) − − + 106 + 16 + + 17 + 122 ↔ + 138 CO NO H PO H H O CH O NH H PO O 2 3 2 4 2 2 3 3 4 2 106 16 - Key role in total alkalinity (TA) distribution: − 2 + + ↔ + + 2 HCO Ca CaCO CO H O 3 3 2 2 - CaCO 3 ballasts particulate organic carbon (POC) and maintains the biological pump that removes CO 2 from the surface ocean to the ocean interior. Understanding the functioning and characteristics of coccolithophorid blooms is of crucial importance to describe the efficiency of the biological pump (Climate Change perspective).

������������ ����������� How important are pelagic calcifiers in the biogeochemical C cycle? • “Carbonate rocks” is the most important reservoir of C on the Earth system Cretaceous Berner, 1998 “ Creta- ” in Latin means • CaCO 3 production is a biotic process “ Chalk ” • Ocean acidification and Global Warming will affect the distribution and the abundance of the pelagic calcifiers. (The Royal Society Report, 2005, IPCC, 2007)

������������ ������������������������ Regional field Biogeochemical Remote surveys models sensing Balch et al., 1992; Robertson et Six and Maier-Reimer, 1996; Holligan et al, 1983; al., 1993; Holligan et al. , 1993, Heinze, 2004 GREPMA , 1988 ; Brown and Fernandez et al. , 1993; Garcia- Yoder, 1994; Balch et al. , Soto et al. , 1995; van der Wal et 2005; 2007 al. , 1995; Head et al., 1998; Rees Brown and Phytoplankton et al. , 1999; Maranon and Yoder, 1994 Gonzalez, 1997; Graziano et al. , functional type- 2000; Lampert et al. , 2001; Rees et al. , 2002; Robertson et al. , based models 2002 Balch et al. , PEACE project… Gregg et al. , 2003; Le Quéré 2007 et al., 2005; Gregg and Casey, 2007 Laboratory experiments Phytoplankton By Paasche in the 60-70s Individual- By Nimer-Merrett-Brownlee in the 80-90s based models pCO 2 manipulations in the 2000th Merico et al., 2004; Pasquer et al. , 2005; Joassin et al. , 2008 Sediment trap synthesis Milliman et al., 1999; Honjo, 2008

������������ ������������������������������ (Balch et al. , 2007)

������������ ������������������������������ Considering that this study reflects coccolithophorid calcification! Coccolithophores (Balch et al ., 2007) ~1.6 Pg PIC yr -1 Foraminifera (Langer et al. , 1997) ~0.16 Pg PIC yr -1 Coral Reefs (Vescei, 2004) ~0.09 Pg PIC yr -1 Pteropods ~10% of the global flux (Honjo, 1981) (Balch et al. , 2007) Benthic Molluscs, Echinoderms… ?

������������ ������������������������������ Considering that this study reflects coccolithophorid calcification! Coccolithophores (Balch et al ., 2007) ~1.6 Pg PIC yr -1 Foraminifera (Langer et al. , 1997) ~0.16 Pg PIC yr -1 Coral Reefs (Vescei, 2004) ~0.09 Pg PIC yr -1 Pteropods ~10% of the global flux (Honjo, 1981) (Balch et al. , 2007) Benthic Molluscs, Echinoderms… ? Coccolithophores are the most important calcifier, actually!!

������������ ����������� � ����� Ocean acidification would reduce the ability of calcifying organisms to form CaCO 3 structures. Global warming in surface waters: • decreases CO 2 solubility • decreases water mixing • enhances stratification • decreasing the mixed layer depth • reducing the DIC inputs • reducing the nutrient inputs • providing higher irradiance for Adapted from Rost and Riebesell, 2004 and Borges et al. , 2008 the marine biota

������������ ����������� � ����� Ocean acidification would reduce the ability of calcifying organisms to form CaCO 3 structures. Global warming in surface waters: • decreases CO 2 solubility • decreases water mixing • enhances stratification • decreasing the mixed layer depth • reducing the DIC inputs • reducing the nutrient inputs • providing higher irradiance for Adapted from Rost and Riebesell, 2004 and Borges et al. , 2008 the marine biota Setup of new conditions No good prediction !!

������������ ��������������������� “… the time taken for a patch to disappear on satellite images can be calculated as >200 days . The maximum lifetime of such patches on satellite images is 30-40 days , suggesting that processes other than sinking are important in their disappearance .” (Holligan et al. , 1993)

������������ ��������������������� “… the time taken for a patch to disappear on satellite images can be calculated as >200 days . The maximum lifetime of such patches on satellite images is 30-40 days , suggesting that processes other than sinking are important in their disappearance .” (Holligan et al. , 1993)

������������ ��������������������� “… the time taken for a patch to disappear on satellite images can be calculated as >200 days . The maximum lifetime of such patches on satellite images is 30-40 days , suggesting that processes other than sinking are important in their disappearance .” (Holligan et al. , 1993) Our knowledge of coccolithophrid blooms is insufficient!!!

������������ ��������������������� Coccolithophores are the most important calcifier, actually!! Setup of new conditions No good prediction !! Our knowledge of coccolithophrid blooms is insufficient!!! What do we know ?

������� ������� • Preambule: – Problematic of coccolithophorid studies – Internal calcification – Lessons from the cultures – Ecological niche • Results: – Bay of Biscay – Multidisciplinary cruises – 2004 – 2006 – 2008 • Perspectives: – Synthesis of field data – Mechanism of bloom development in the Bay of Biscay – Conceptual model for coccolithophorid calcification

������������ ���������������������� Takes place in vesicles derived • from the Golgi apparatus • Nucleation occurs around a fibrillar base-plate • Involves specific polysaccharides • The new coccolith migrates into the cytoplasm and is released by exocytosis to the cell periphery • Coccoliths are produced in excess and detach from the cell ������ ����������� van der Wal et al., 1983

������������ ��������������������� Schematic development of a coccolithophorid bloom 40 Synthesis of biomass 30 Chl-a (µg L -1 ) 20 10 0 0 20 40 60 Day De Bodt et al. , in prep

������������ ��������������������� Schematic development of a coccolithophorid bloom 40 Synthesis of biomass 30 Chl-a (µg L -1 ) 20 10 0 0 20 40 60 Day 6 Consumption of nutrients PO 4 (µmol L -1 ) 4 2 0 0 20 40 60 Day 50 40 NO 3 (µmol L -1 ) 30 20 10 0 De Bodt et al. , in prep 0 20 40 60 Day

������������ ��������������������� Schematic development of a coccolithophorid bloom 40 Synthesis of biomass Production of CaCO 3 30 Chl-a (µg L -1 ) 2500 80 TA corrected (µmol kg -1 ) 20 CaCO 3 (mg kg -1 ) 2000 60 10 1500 40 0 0 20 40 60 1000 20 Day 6 Consumption of nutrients 500 0 0 20 40 60 PO 4 (µmol L -1 ) Day 4 2 0 0 20 40 60 Day 50 40 NO 3 (µmol L -1 ) 30 20 10 0 De Bodt et al. , in prep 0 20 40 60 Day