The dimethylsulfide cycle in the eutrophied Southern North Sea: a model study integrating phytoplankton and bacterial processes

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The dimethylsulfide cycle in the eutrophied

Southern North Sea: a model study

integrating phytoplankton and bacterial

processes

26-30 May 2014 Barcelona, Spain

N. Gypens1_{, A.V. Borges}2_{, G. Speeckaert}1 _{and C. Lancelot}1 1 _{Université Libre de Bruxelles, Belgium}

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Objective and methodology

• What is the

seasonal

variability of DMS emissions? What is the

importance of

phytoplankton succession

on DMSP production and

DMS emission?

Objective: To investigate the link between ecosystem structure and DMS

emission

Methodology: MIRO-DMS model applied to the Southern North Sea

• What is the relative importance of

phytoplankton and bacterial

processes

on DMS emission?

• What is the

impact of anthropogenic pressure

(C and nutrient river

loads, atmospheric CO

₂

increase) on DMS emission?

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 Eutrophied area → Phaeocystis (Haptophyceae) High DMSP producers → Diatoms Low DMSP producers Chl a in 2005 May Source: ECOMAR GEM-IES → Ecosystem disturbance  High primary production

0 100 200 300 400 500 600 Month Ph yt op la nk to n b io m as s, m gC m -3 J F M A M J J A S O N D Diatoms Phaeocystis Not grazed Foam accumulation

The Southern Bight of the North Sea

26-30 May 2014

Barcelona, Spain

 High nutrients loads

Atlantic waters

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Lancelot et al., 2005 GRA PO₄ NH₄ NO₃ DSi BC DAF Diatoms growth photos & resp. growth & resp. CO₂ DAS DAR Lysis & excretion NFF growth photos & resp. NFS NFR Autotrophic flagellates heterotrophic. bact. exoenz. hydrol Excretion minera-lization CO2 MZ Grazing growth & resp. mortality microzooplankton Copepods nitrif. nitrif. NO₃ NH₄ organ.matter degrad. O xi c la ye r A n o xi c la ye r PCNP _1,2 denit. PO₄ ads PO4 BSi dissol. _sedim. O2 Sediment accretion OPF growth photos

& resp. OPS OPR

Phaeocystis colonies Grazing growth & resp. CP fixed C:N:P fixed C:N:P fixed C:N:P DN_1,2 DP_1,2 DC_1,2 PN_1,2 PP1,2 PC_1,2 BSN BSC PO4 fixed C:N:P fixed C:N:P fixed C:N:P OPM mucus CO₂ CO₂ Colony disruptn

Mathematical tool: the MIRO model

26-30 May 2014

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[

]

SC_n n sed grazing n lysis n µ dt dDMSPp * − − − =

(

)

n n n uptake n DMS lysis SC grazing SC DMSPd y dt dDMSPd − + − = 1 * * * DMS uptake n n n

DMS lysis SC bacterial hydrolysis DMS photooxydation F

y dt dDMS − − − + = * * _

For n=DA, NF and OP

Mathematical tool: the DMS(P) module

26-30 May 2014

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Mathematical tool: MIRO-DMS implementation

26-30 May 2014

Seasonal cycle: METTRE CONDITIONS DE SIMULATION

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The DMS(P) seasonal evolution

26-30 May 2014

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The DMS(P) seasonal evolution

26-30 May 2014

Parameters Units Values Annual mean [DMS] FDMS

(µmolS m-3) (mmolS m-2 y-1)

REFERENCE 0.9 0.19

Test 1 SCNF, SCOP mol S:molC 0.018 1.5 0.32

Test 3 SCDA mol S:molC 0.00212 0.9 0.21

Test 4 SCDA mol S:molC 0 0.8 0.18

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Phytoplankton vs bacterial processes

26-30 May 2014

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The DMS(P) seasonal evolution

26-30 May 2014

Sensitivity to phytoplankton, bacterial and physical parameters

Parameters Units Values Annual mean [DMS] FDMS

(µmolS m-3) (mmolS m-2 y-1)

REFERENCE 0.9 0.19

Sensitivity to phytoplankton parameters

Test 4 SCDA mol S:molC 0 0.8 0.18

Test 6 yDADM S, y NF DM S, y OP DM S - 0 0.5 0.11 Test 7 yDADM S, y NF DM S, y OP DM S - 0.25 1.4 0.32 Test 8 yDADM S, y NF DM S, y OP DM S - 0.5 2.4 0.53 Test 9 yNFDM S, y OP DM S - 0.5 2.3 0.51 Test 10 yDADM S - 0.5 0.9 0.21

Sensitivity to bacteria parameters

Test 11 SCBC mol S:molC 1:37 0.8 0.17

Test 12 SCBC mol S:molC 1:196 0.9 0.2

Test 13 RatioBC - 0.75 1.1 0.24

Test 14 RatioBC - 0.5 1.4 0.32

Test 15 RatioBC for DMSPd - 0.5 0.9 0.2

Test 16 RatioBC for DMS - 0.5 1.4 0.32

Test 17 khydrolysis - 0.25 1.6 0.35

Sensitivity to wind speed and k parameterization

Test 18 wind forcing m s-1 3.9 0.9 0.24

Test 19 wind forcing m s-1 -25% 0.9 0.13

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The DMS(P) seasonal evolution

26-30 May 2014

Sensitivity to phytoplankton, bacterial and physical parameters

Phytoplankton parameters

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Hydrological network morphology

Water quality in the hydrological

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Description of ecological

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MIRO-DMS

100 km North Sea Channel WCH _FCZ BCZ Seine Scheldt Somme Rhine N * 330

Diatoms and undesirable Phaeocystis blooms in the coastal

zone and

CO2and DMS emissions

Impact of anthropogenic pressure

26-30 May 2014

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Impact of anthropogenic pressure

26-30 May 2014

Faire la meme figure avec seulement les résus de la simulation de référence

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Faire la meme figure avec seulement les résus de la simulation de référence et pH simulation

Mettre graphe evolution pCO2 atm

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Mettre graphe evolution pCO2 atm

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26-30 May 2014

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