Diversity decoupled from ecosystem function and resilience during mass extinction recovery.

Area of Science:

• Paleoceanography
• Marine Ecology
• Biogeochemistry

Background:

• The Chicxulub bolide impact 66 million years ago caused a mass extinction event, leading to the collapse of ocean ecosystems and disruption of global biogeochemical cycles.
• Understanding the timescale and mechanisms of ocean ecosystem recovery and restoration of biogeochemical functions post-impact has been limited by a lack of detailed biotic data.

Observation:

• Analysis of a 13-million-year nannoplankton time series reveals a 1.8-million-year period of significant community instability following the Chicxulub impact.
• A shift towards a more stable, equilibrium-state community with a wider range of cell sizes was observed.
• This transition coincided with the restoration of carbon cycle processes and a fully functioning biological pump.

Findings:

• Ocean ecosystems exhibited 1.8 million years of volatility before achieving a resilient equilibrium state after the Chicxulub impact.
• The emergence of community stability and biological pump function was linked to the restoration of the carbon cycle.
• Ecological functions, rather than just species richness, appear crucial for community resilience and biogeochemical recovery.

Implications:

• Ecosystem recovery and biogeochemical cycling are fundamentally linked over long timescales, with functional restoration occurring faster than the return of full taxonomic richness.
• The study suggests that ecological functions, such as those supporting the biological pump, are key indicators of ocean resilience post-disturbance.
• These findings refine estimates of ecosystem recovery duration, highlighting the importance of functional processes in marine environments after major extinction events.