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UniGib lecturer helps shed light on mass extinction event

A University of Gibraltar lecturer has contributed to a study that sheds light on the last mass extinction event. In an article published last week in the influential scientific journal Science Advances, scientists revealed how some marine plankton managed to survive the Cretaceous/Paleogene mass extinction.
The extinction, which was triggered by an asteroid impact 66 million years ago, is well known for the loss of dinosaurs, ammonites and many other groups. It also had a massive effect on the marine plankton that underpin the ocean ecosystem. What has puzzled researchers up to now is how some plankton survived and recolonised the ocean, while many others perished.
The team, which includes University of Gibraltar lecturer Dr Sarah Alvarez and collaborators from Southampton, London, Paris, Edinburgh and California, present remarkable fossil evidence combined with results from a new eco-evolutionary model to examine the species that survived the impact and thrived in the aftermath.
‘The post-impact darkness was a key cause of extinction in calcareous nannoplankton, which are a key marine plankton group’ says Dr Alvarez. ‘There was so much debris in the atmosphere following the asteroid impact that these organisms, which typically photosynthesise to produce energy, were starved of sunlight. By examining fossil remains obtained from deep sea sediments, we were able to identify a common feature of the successful species, which gave us a clue as to how they managed to survive and recolonise the ocean.’
The feature that Dr Alvarez refers to is a particular skeletal structure, which indicates that the successful plankton were able to hunt and consume other organisms instead of relying on photosynthesis. ‘We have grown used to thinking of these plankton as plant-like organisms, which is typically how they behave in the ocean today’ says Dr Alvarez. ‘Our new observations show that the ancestors of modern calcareous nannoplankton had a predatory capacity, and this has been a real game-changer.’
Dr Alvarez is enjoying sharing her latest research insights and fascination of microplankton and their fossil remains with the new cohort of MSc Marine Science & Climate Change students at University of Gibraltar. ‘It’s important that we use evidence from the past to fully appreciate the effects of ongoing environmental change’ she says.

Image credit: P. Bown at UCL

Read the full study:

Gibbs, Bown, Ward, Alvarez et al. (2020) Algal plankton turn to hunting to survive and recover from end-Cretaceous impact darkness. Science Advances Vol. 6, no. 44, eabc9123 DOI: 10.1126/sciadv.abc9123 .