Resilience of primary and export productivity in a eutrophic ecosystem following the Cretaceous-Paleogene mass extinction

The recovery time of marine productivity following the Cretaceous-Paleogene (KPg) mass extinction varies tremendously with location (hundreds to millions of years), with possible delays in the tropics as compared to higher latitudes. This heterogeneity is based on prevalent oligo- to mesotrophic marine environments. While highly productive eutrophic environments are less prevalent, they play a greater role in the carbon cycle. Here we present data from a eutrophic region within the tropical southern Tethys. Records of both organic matter and calcite production in this locality exhibit stability across the KPg boundary. In addition, our study points to a remarkably rapid recovery (<11 kyr), even possibly continuous high productivity across the KPg boundary, despite the tropical location. Moreover, the characteristic KPg δ¹³C negative excursion is observed in our locality, but is independent of high productivity, possibly indicating a reduction in the δ¹³C of the DIC of the ocean due to the input of light carbon from the atmosphere. Thus, this study provides new insight into the functioning of eutrophic ecosystems during environmental stress imposed by the ecological crisis.