Diversity decoupled from ecosystem function and resilience during mass extinction recovery

Abstract

The Chixulub bolide impact 66 million years ago drove near-instantaneous oceanic ecosystem collapse. Devastating diversity loss at the base of ocean food-webs likely triggered cascading extinctions across all trophic levels 1-3 and caused severe disruption of ocean biogeochemical function, especially the cycling of carbon between the surface and deep sea 4,5. The absence of sufficiently detailed biotic data spanning the postextinction interval has limited our understanding of how ecosystem resilience and biochemical function was restored, with estimates of 'recovery' varying from <100 years to 10 million years 6-8. Using a 13-million-year long nannoplankton time-series we show that post-extinction communities exhibited 1.8 million years of exceptional volatility before a more stable equilibrium community emerged displaying hallmarks of resilience. The transition to this new equilibrium-state community with a broader cellsize spectrum coincides with indicators of carbon cycle restoration and a fully functioning biological pump 9. This finding implies a fundamental link between 93 perturbation (i.e., the significant linear trend between carbon isotope excursion and variance) 94 and rapid recoveries following each event (return of variance to the background state within 95 <200 kyrs of the excursion, Fig. 1c and ref 21). 96 Tantalisingly, the shift to more stable communities approximately 64.2 Myr ago (the end of 97 Regime 1) also falls towards the top of the interval of biological pump recovery 9 (Fig. 3f). 98 Ocean biogeochemical function was profoundly disrupted by the end-Cretaceous mass 99 extinction, most obviously through weakening of the biological pump 2,5,9. The scale and duration of this productivity reduction is contentious, ranging from scenarios of a lifeless Strangelove Ocean to a partially functioning Living Ocean state 4 , but the long, multimillionyear delay in restoration of the biological pump is well established 2,22 , and indicated by both the gradual increase in vertical carbon isotope gradient to pre-extinction values 9 and changing community structures of benthic primary-consumer communities (benthic foraminifera) 23. Carbon isotope gradients finally returned to pre-extinction values by ~1.77 Myrs after the event 9 providing an upper limit on full recovery of the biological pump. This broad

No Cretaceous‐Paleogene Boundary in Exposed Rajahmundry Traps: A Refined Chronology of the Longest Deccan Lava Flows From40Ar/39Ar Dates, Magnetostratigraphy, and Biostratigraphy

“…Ecological community stability was highly variable for the first ~700 ka of the Paleocene, until ~65.3 Ma (Alvarez et al, 2019; see also Birch et al, 2016; Smith et al, 2018). There are several periods of climate change during this time interval, including the Danian‐C2 (Dan‐C2) and lower‐C29n hyperthermal events (Coccioni et al, 2010; Dinarès‐Turell et al, 2014).…”

The origin and diversification of pteropods precede past perturbations in the Earth’s carbon cycle

“…2). Many pelagic groups disappeared during the well-known mass extinction at the K-Pg boundary (51,52), and, though it is difficult to pinpoint a specific cause of these changes (17), recent evidence from boron isotopes in foraminifers shows that rapid surface ocean acidification was associated with the impact (53). The PETM also had an impact on marine calcifiers, as shown by a rapid decrease in calcium carbonate content in marine sediments (54) and the recording of one of the largest extinctions among deep-sea benthic foraminifers (49,55).…”

Time Machine Biology: Cross-Timescale Integration of Ecology, Evolution, and Oceanography

“…Ecological interactions in addition to climate, for example, have been found to influence the macroevolution of planktonic foraminifera (Ezard et al, 2011). Continued study of biotic traits will allow for examination of the relative roles of abiotic (e.g., climate) versus biotic factors in shaping ecosystems and their changes through time (Schmidt et al, 2004), as well as of the relationship between biodiversity and ecosystem function (Henehan et al, 2016;Alvarez et al, 2019).…”