Biogeochemical significance of pelagic ecosystem function: an end-Cretaceous case study.
Pelagic ecosystem function is integral to global biogeochemical cycling, and plays a major role in modulating atmospheric CO2 concentrations (pCO2). Uncertainty as to the effects of human activities on marine ecosystem function hinders projection of future atmospheric pCO2 To this end, events in the geological past can provide informative case studies in the response of ecosystem function to environmental and ecological changes. Around the Cretaceous-Palaeogene (K-Pg) boundary, two such events occurred: Deccan large igneous province (LIP) eruptions and massive bolide impact at the Yucatan Peninsula. Both perturbed the environment, but only the impact coincided with marine mass extinction. As such, we use these events to directly contrast the response of marine biogeochemical cycling to environmental perturbation with and without changes in global species richness. We measure this biogeochemical response using records of deep-sea carbonate preservation. We find that Late Cretaceous Deccan volcanism prompted transient deep-sea carbonate dissolution of a larger magnitude and timescale than predicted by geochemical models. Even so, the effect of volcanism on carbonate preservation was slight compared with bolide impact. Empirical records and geochemical models support a pronounced increase in carbonate saturation state for more than 500 000 years following the mass extinction of pelagic carbonate producers at the K-Pg boundary. These examples highlight the importance of pelagic ecosystems in moderating climate and ocean chemistry.
Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT 06511, USA michael.henehan@yale.edu.
Michael J
0000-0003-4706-1233
MJ
Henehan
Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT 06511, USA.
Pincelli M
0000-0001-8607-4817
PM
Hull
Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT 06511, USA.
Donald E
DE
Penman
Department of Earth Sciences, University of St Andrews, Irvine Building, St Andrews KY16 9AL, UK.
James W B
JW
Rae
Department of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol BS8 1RJ, UK.
Daniela N
0000-0001-8419-2721
DN
Schmidt
D057486:Carbon Cycle; D002254:Carbonates / Q000032:analysis; D017753:Ecosystem; D053476:Extinction, Biological; D009792:Oceans and Seas; D012623:Seawater / Q000737:chemistry*
D002254:Carbonates
Cretaceous–Palaeogene extinction; LOSCAR; biogeochemical cycling; bolide impact; ecosystem function; mass extinction