A Resilient Ocean: New Insightsโฃ into Mass Extinction Recovery
The Earth has experienced five major โmass โextinction events, periods of catastrophic species loss driven by global โchange. Scientists now โคbelieve we โขare on โฃthe precipice of a sixth. Understanding how ecosystems rebound from such devastation is therefore critical, and a recent study led by โคDavid Jablonski atโค the University of Chicago is challenging long-held assumptions about โฃthe โrecovery process following the most recent extinction โข- the end of theโ Cretaceous period.
This event, famous for wiping out the dinosaurs, eliminated over three-quarters of all species.โฃ Jablonski’sโ team focused on marine mollusks – shellfish, โoysters, โand others – due toโค the โคexcellent fossil record provided โby their durable shells. By โmeticulously reconstructing the ecological landscape before the extinction and comparing it to the species present afterward, they uncovered a surprising result: despiteโ the massive loss โof โlife, the fundamental โecological structure of the marine environment remained remarkably intact.
“If 75% โof allโ species are extinct, you would โexpect that at least โฃa fewโ waysโ of life wouldโข be entirely lost, leavingโ onlyโ one orโค two species to fill thoseโฃ roles,” explains Katie Collins of the London Natural History Museum. โ”But that’s not what we see.”
This finding contradicts โprevious theories about extinction recovery.โข For decades,โ some scientistsโข believedโข mass extinctions โsimply accelerated โขpre-existing evolutionary trends – dinosaurs were destined to โคbe replaced by mammals,โ and the asteroid impact merely sped โขup the โฃprocess. Others proposed that extinctions acted as a selective pressure, favoring species capable of evolvingโค toโ fill newly availableโฃ niches.โ
Jablonski’s research doesn’t support either of these ideas. He โviews the resultsโ as a warning,highlighting a gap in our understanding โof howโ biodiversity โloss impacts ecological function. “we do not understand how the loss of functional groups relates to the loss of biodiversity,” he states.
further complicating the picture, โthe study revealed that the species which did โ survive didn’t โnecessarily thrive in a predictable manner. Contrary to expectations,survivors didn’t uniformly capitalize on opportunities and rapidly diversify. โคWhile this pattern โขmight hold true for mammals, Jablonski โfound it wasn’t the case inโ marine ecosystems, with recovery appearing โคmore random.
This โขresearch has meaningful implications for modern ocean conservation. โ With theโ seas facing threats like acidification, pollution, โคand overfishing, understanding how ecosystems respond to large-scale disruption is paramount. โคJablonski emphasizes the need to consider โคthe broader ecological structure, not โคjust individual species, when developing management policies and establishing marine reserves.โค โข”This is something we really โwant to understand โคif โคwe wantโข to โฃdiscuss โmodern extinction and recovery in the ocean, as well as how to manage it,” he explains. “Billions of people depend on the sea for food, โand we can see โthat nature โคreserves and management policies need to considerโค the wider biota ecological โฃstructure, not just individualโฃ species.”
The study,published in Science Advances โ on May โ21,2025,is titled “The end-Cretaceous โขmass extinction restructuredโ functional diversity but failed โคto configure the modern marine biota.”
(Original Content)