Ecological Response of Plankton to Environmental Change – Thresholds for Extinction

Abstract

Severe climatic and environmental changes are far more prevalent in Earth history than major extinction events, and the relationship between environmental change and extinction severity has important implications for the outcome of the ongoing anthropogenic extinction event. The response of mineralized marine plankton to environmental change offers an interesting contrast to the overall record of marine biota, which is dominated by benthic invertebrates. Here, we summarize changes in the species diversity of planktic foraminifera and calcareous nannoplankton over the Mesozoic-Cenozoic and that of radiolarians and diatoms over the Cenozoic. We find that, aside from the Triassic-Jurassic and Cretaceous-Paleogene mass extinction events, extinction in the plankton is decoupled from that in the benthos. Extinction in the plankton appears to be driven primarily by major climatic shifts affecting water column stratification, temperature, and, perhaps, chemistry. Changes that strongly affect the benthos, like acidification and anoxia, have little effect on the plankton, or are associated with radiation.

Early Paleocene Paleoceanography and Export Productivity in the Chicxulub Crater

“…At the end of the Cretaceous Period (66.0 Ma), the impact of an asteroid on the Yucatán carbonate platform in the southern Gulf of Mexico caused the extinction of 75% of marine species (Alvarez et al, 1980;Smit et al, 1980;Hildebrand et al, 1991;Jablonski, 1995;Schulte et al, 2010), including ~90% of pelagic calcifiers such as planktic foraminifera and calcareous nannoplankton (Bown, 2004;Fraass et al, 2015;Lowery et al, 2020). Dust and sulfate aerosols ejected from the evaporite-rich carbonate target rock and soot from widespread wildfires blocked the sun, resulting in severe short-term cooling (Wolbach et al, 1985;Pope et al, 1994;Vellekoop et al, 2014Vellekoop et al, , 2016Bardeen et al, 2017Brugger et al, 2017Artemieva et al, 2017;Gulick et al, 2019;Artemieva and Morgan, 2020) and collapse of the food chain due to a sharp decline in photosynthesis (Zachos et al, 1989;Kring, 2007).…”

Subtropical to temperate late Neogene to Quaternary planktic foraminiferal biostratigraphy across the Kuroshio Current Extension, Shatsky Rise, northwest Pacific Ocean

“…Such robust biostratigraphic schemes and detailed speciation histories for marine plankton have allowed for investigations into the drivers of speciation and diversity through time (e.g. [ 7 – 9 ]). However, by comparison, detailed investigations of mid-latitude plankton biostratigraphy and speciation are underrepresented.…”

Enhanced fish production during a period of extreme global warmth

“…Despite consistent model-based predictions of declining primary and higher trophic-level production with anthropogenic-scale ocean warming, geological records are less clear regarding the relationship between global ocean temperature and marine productivity on long timescales, with some records showing positive correlations, and others showing negative correlations or no relationship at all 15 – 19 . Furthermore, the sedimentary record of marine production is limited to the tiny fraction of the ecosystem that makes it to the seafloor 17 , primarily the fossils of biomineralizing phytoplankton 20 (calcareous coccolithophores and siliceous diatoms) which make up less than half of modern primary production 21 . Thus quantitative information on primary and higher trophic level production is largely absent from the geologic record, leaving a gap in our understanding of how fixed carbon may transfer up the food web during periods of long-term global warming.…”