Size was once a form of protection for the bigger marine animals – but now they are the ones most likely to become extinct.
So say scientists who have been comparing the associations between extinction threat and ecological traits in modern marine animals with those links observed during the Earth’s previous mass-extinction events.
Using a database of some 2500 marine vertebrates and molluscs, the researchers found that extinction threat is now strongly associated with large body size, whereas in the past either size was not relevant or it was the smaller animals most at risk.
In previous mass extinctions it was also pelagics that were more likely to be endangered, though this is no longer necessarily the case.
The difference was made by the arrival of human hunters, who seek out larger prey for greater rewards and are not intimidated by their size – and their influence does not bode well for the future.
“The differential importance of large-bodied animals to eco-system function portends greater future ecological disruption than that caused by similar levels of taxonomic loss in past mass-extinction events,” says the paper.
Terrestrial biodiversity is declining rapidly, and the oceans are poised to follow suit, say the scientists. Without human intervention, a sixth mass extinction could approach or exceed the magnitude of the five major extinctions of the past 550 million years, such as those that wiped out reef-building animals and non-flying dinosaurs.
Such an event would signal the start of a new geological epoch, period or even era.
“Ecological Selectivity of the Emerging Mass Extinction in the Oceans” by Jonathan Payne of Stanford University and four other US scientists is published in Science – read it here
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21-Sep-16
