Articles | Volume 14, issue 4
Biogeosciences, 14, 885–900, 2017
Biogeosciences, 14, 885–900, 2017

Research article 27 Feb 2017

Research article | 27 Feb 2017

Ecological response to collapse of the biological pump following the mass extinction at the Cretaceous–Paleogene boundary

Johan Vellekoop1,2,*, Lineke Woelders2,*, Sanem Açikalin3, Jan Smit4, Bas van de Schootbrugge1, Ismail Ö. Yilmaz5,6, Henk Brinkhuis1,7, and Robert P. Speijer2 Johan Vellekoop et al.
  • 1Marine Palynology, Laboratory of Palaeobotany and Palynology, Faculty of Geosciences, Utrecht University, Utrecht, 3584 CD, the Netherlands
  • 2Division of Geology, Department of Earth and Environmental Sciences, KU Leuven, Leuven-Heverlee, 3001, Belgium
  • 3School of Civil Engineering and Geosciences, Newcastle University, NE1 7RU, Newcastle upon Tyne, UK
  • 4Department of Sedimentology and Marine Geology, Faculty of Earth and Life Science, Vrije Universiteit Amsterdam, Amsterdam, 1018HV, the Netherlands
  • 5Department of Geological Engineering, Middle East Technical University, Ankara, Turkey
  • 6Department of Geological Sciences, University of Texas at Austin, Austin, TX 78712, USA
  • 7Royal Netherlands Institute for Sea Research (NIOZ), Landsdiep 4, 't Horntje, Texel, 1797 SZ, the Netherlands
  • *These authors contributed equally to this work.

Abstract. It is commonly accepted that the mass extinction associated with the Cretaceous–Paleogene (K–Pg) boundary (∼ 66 Ma) is related to the environmental effects of a large extraterrestrial impact. The biological and oceanographic consequences of the mass extinction are, however, still poorly understood. According to the Living Ocean model, the biological crisis at the K–Pg boundary resulted in a long-term reduction of export productivity in the early Paleocene. Here, we combine organic-walled dinoflagellate cyst (dinocyst) and benthic foraminiferal analyses to provide new insights into changes in the coupling of pelagic and benthic ecosystems. To this end, we perform dinocyst and benthic foraminiferal analyses on the recently discovered Tethyan K–Pg boundary section at Okçular, Turkey, and compare the results with other K–Pg boundary sites in the Tethys. The post-impact dominance of epibenthic morphotypes and an increase of inferred heterotrophic dinocysts in the early Paleocene at Okçular are consistent with published records from other western Tethyan sites. Together, these records indicate that during the early Paleocene more nutrients remained available for the Tethyan planktonic community, whereas benthic communities were deprived of food. Hence, in the post-impact phase the reduction of export productivity likely resulted in enhanced recycling of nutrients in the upper part of the water column, all along the western Tethyan margins.

Short summary
The Cretaceous–Paleogene boundary, ~ 66 Ma, is characterized by a mass extinction. We studied groups of both surface-dwelling and bottom-dwelling organisms to unravel the oceanographic consequences of these extinctions. Our integrated records indicate that a reduction of the transport of organic matter to the sea floor resulted in enhanced recycling of nutrients in the upper water column and decreased food supply at the sea floor in the first tens of thousands of years after the extinctions.
Final-revised paper