Presentation on theme: "Do burrowing organisms influence carbon processing on a global scale? A data mining approach. Frank Bockelmann Olivier Maire Filip Meysman Laboratory of."— Presentation transcript:
Do burrowing organisms influence carbon processing on a global scale? A data mining approach. Frank Bockelmann Olivier Maire Filip Meysman Laboratory of Analytical and Environmental Chemistry Vrije Universiteit Brussel (VUB) Pleinlaan 2, 1050 Brussel
1.Burrowing organisms in marine environments A fresh look at Darwin‘s last idea 2.Carbon cycling in the ocean The role of the seafloor 3. Does macrofaunal activity affect organic matter processing on a global scale? A data mining approach 4. Preliminary results OUTLINE
1. Burrowing organisms in marine environments A fresh look at Darwin‘s last idea
Charles Darwin *12 Feb 1809, †19 Apr A fresh look at Darwin’s last idea
Bioturbation is the displacement and mixing of sediment particles by benthic animals or rooting plants resulting in disturbance of sediment layers. Solan et al., MEPS (2004) Spidercrab (Hyas araneus) 1. A fresh look at Darwin’s last idea
Bioirrigation is the process of benthic organisms flushing their burrows with seawater thereby exchanging dissolved substances between the porewater and overlying seawater. Brittle star Stahl & Glud, L&O (2006) Evolution O 2 concentration at particular point 1. A fresh look at Darwin’s last idea
Ocean floor without fauna O2O2 SO 4 Anoxic sediment 5 mm microbial mats shallow O 2 penetration diffusive transport 10 cm ventilated burrow systems increased O 2 supply biol. mediated transport Ocean floor with fauna 1. A fresh look at Darwin’s last idea after Meysman, et al., Trends Ecol. Evol. (2006)
Slide 02/15 2. Carbon cycling in the ocean The role of the seafloor
Atmosphere Deep Ocean Deepsediment Surface sediment Upper ocean 0.4% 5% 4.6% CO 2 + H 2 O CH 2 O + O 2 Recycling 15% 80% Carbon fixation (~54 Pg yr -1 ) CO 2 + H 2 O CH 2 O + O 2 ExportRelease Burial 200 m after Sarmiento and Gruber, 2006 Slide 02/15 Organic carbon sequestration Oxygen accumulation CO 2 sequestration CO 2 O2O2 CH 2 O 2. Carbon cycling – The role of the seafloor
Return CO 2 to water column Sequestration in deeper sediments 92 % 8 % Seafloor flux The seafloor – An efficient „batch reactor“ Total area:~ 362 Mio km 2 Reservoir size:150*10 15 gC Turnover time: 0.1 – 1000 yr
redrawn from Seiter et al., DSRII (2004) Critical questions to be asked... How much carbon goes, how much stays? How does this efficiency vary between environments? What controls the recycling efficiency? 2. Carbon cycling – The role of the seafloor Deep sea Continental margins Organic matter input Organic carbon content Macrofaunal activity
reproduced from Burdige, Chem. Rev. (2007) 2. Carbon cycling – The role of the seafloor Is macrofaunal activity a key player at the global scale?
3. Does macrofaunal activity affect organic matter processing on a global scale? A data mining approach
Data-mining 3. A data mining approach GIS Parameterization Modelling Quantitative assessment of macrofauna affect on sedimentary carbon cycling at a global scale
The model parameters in focus Bioturbation Burial Degradation Bio-irrigation O2-consumption 3. A data mining approach
The model parameters in focus Independent variables water depth temperature, salinity primary production Sediment type porosity density sand, silt, clay content Sediment transport bioturbation coefficient (D b ) bioirrigation coefficient (α) burial velocity (v) mixed layer depth mass flux to seafloor O 2 consumption diffusive O 2 uptake (DOU) total O 2 uptake (TOU) O 2 penetration depth bottom water O 2 content Organic matter seafloor flux surface sediment content burial flux decay rate constant (k) remineralization flux (ΣCO 2 ) 3. A data mining approach
Sediment O 2 uptake Bioturbation coefficient (D b ) TOU DOU 210 Pb 234 Th 3. A data mining approach
4. Preliminary results
ETOPO 1 Min. Global Bathymetry (NGDC/NOAA, 2008) ~ 10% < 1000m
4. Preliminary results Total organic matter degradation (TOU) Organic matter degradation supported by physical transport only (DOU) Extra organic matter degradation induced by the presence of fauna (TOU-DOU = FMOU) Glud, Mar. Biol. Rev. (2008) Sediment O 2 uptake as a measure of remineralization
4. Preliminary results Globally, TOU accounts for remineralization of 2.74 PgC yr -1 of that 70% DOU and 30% FMOU. Continental margins (above 1000m) release 1.84 PgC yr -1 (67% of global R ox ) of that 54% DOU and 46% FMOU. Shutting down macrofaunal activity at continental margins would result in ~ 5fold increase in C-burial! FMOU TOU 30 % 67 %
Things to remember... Macrofauna enhances the sediment oxygen uptake through bioturbation and bio-irrigation Benthic activity has large effect on local biogeochemistry of the ocean floor (ecosystem engineering) Continental margin sediments play a crucial role in organic matter processing at a global scale (Global) carbon balance estimates are extremely sensitive to the representation of benthic activity However, Ocean floor is a more variable environment than anticipated Sampling with respect to basal model parameters tends to exclude large areas (e.g., Db bias to Atlantic; k bias to Pacific) A more systematic approach towards deposition of data into repositories is desirable.
Funding through FWO-Odysseus project to Filip Meysman "Quantifying Darwin's last idea: the influence of bioturbation on the biogeochemistry of marine sediments, and its impact on the global carbon cycle"