article_snippet.sent: This is according to a British study that has discovered a catastrophic condition called 'marine photic zone euxinia' took place in one of the prehistoric oceans.
article_snippet.sent: This happens when the sun-lit surface waters of the ocean become devoid of oxygen and are poisoned by hydrogen sulphide.
article_snippet.sent: Pictured is an artist's impression of what may have happened in the oceans 200 million years ago.  
article_snippet.sent: Hydrogen sulphide is a by-product of micro-organisms that live without oxygen and is extremely toxic to most other lifeforms.
article_snippet.sent: The experts found signs of bacteria which had suffered severe oxygen depletion and hydrogen sulphide poisoning which would have been caused by massive volcanic rifts in the Earth's tectonic plates. '
article_snippet.sent: These changes have the potential to disrupt nutrient cycles and alter food chains essential for the survival of marine ecosystems.
article_snippet.sent: Our data now provides direct evidence that anoxic, and ultimately euxinic, conditions severely affected food chains. '
highlights_snippet.sent: This created disastrous condition dubbed 'marine photic zone euxinia'
  
highlights_snippet.sent: This happens when surface ocean waters become devoid of oxygen .