Lenton, T.M.

Meysman, F.J.R.

Mills, B.J.W.

Poulton, S.W.

Van de Velde, S.

Open Marine Archive

 28 
The evolution of burrowing fauna triggered a low-oxygen ocean and 
global warming 
Van De Velde Sebastiaan
1
, Mills Benjamin J.W.
2
, Lenton Timothy M.
3
, Poulton Simon W.
3
 and Meysman 
Filip J.R.
4 
1
  Analytical, Environmental and Geochemistry, Department of Chemistry, Vrije Universiteit Brussel, 
Pleinlaan 2, 1050 Brussel, Belgium 
 E-mail: sebastiaan.van.de.velde@vub.be 
2
  School of Earth and Environment, University of Leeds, LS2 9JT, Leeds, United Kingdom 
3
  Earth System Sceince Group, University of Exeter, EX4 4QE, Exeter, United Kingdom 
4
  Ecosystem Management Research Group, Department of Biology, Universiteit Antwerpen, 
Universiteitsplein 1, 2160 Antwerpen, Belgium 
 
Most of the present-day oxygenated seafloor is colonised by fauna. Animal movement and feeding has 
a major effect on the sedimentarey biogeochemical cycles. We are starting to understand the effect 
of burrowing on modern-day sediments, but it is still unclear what the long-term effects are for the 
global biogeochemical cycles of carbon, oxygen, sulphur and phosphorus. 
 
Here we present a combination of in situ observations and diagenetic modelling results. Bioturbation 
stimulates the oxygen uptake of the sediment, decreases organic carbon burial and promotes 
phosphate burial. Furthermore, re-oxidation of reduced iron sulphides is stimulated, thereby 
promoting sulphur recycling. Modelling results indicate that these effects already occur at burrowing 
depths of the same magnitude that were present at the beginning of the Cambrian explosion. 
 
We apply these present day observations to a long-term box model of the geochemical evolution of 
the early earth. Results show that animal colonisation of the seafloor in the Early Palaeozoic 
significantly affected the global cycles of carbon and oxygen. The evolution of shallow burrowing 
contributed to a global low-oxygen state, which prevailed for ~100 million years until the evolution 
of land plants caused a rise in atmospheric O2 towards modern levels. Additionally, enhanced 
sedimentary phosphorus retention limited primary production, which led to an expansion in ocean 
anoxia, while decreased carbon burial allowed atmospheric CO2 levels to rise, giving rise to global 
warming. 
 
Keywords: modelling; bioturbation; global biogeochemical cycles; evolution  


The evolution of burrowing fauna triggered - a low-oxygen ocean and global warming

http://www.vliz.be/imisdocs/publications/311855.pdf

The evolution of burrowing fauna triggered - a low-oxygen ocean and global warming

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