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The much-maligned rat is not a creature that many would badociate coral reefs.
But scientists studying tropical island reefs say that animals directly threaten the survival of these ecosystems.
A team working on the Chagos Islands in the Indian Ocean found that invasive rats on the islands are a "big problem" for coral reefs.
Rats decimate seabird populations, decimating in turn the volume of droppings. coral fertilizer.
Results are published in Nature
Scientists now advocate the eradication of rats from all islands to protect these delicate marine habitats.
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Nick Graham
How do rats harm coral reefs?
The Chagos Archipelago provided a large-scale natural laboratory to answer this question; Although the islands are uninhabited by humans, some of them are now home to invasive rats, brought by ships and wrecks. Other islands remained free of rats.
"The islands with and without rats are like chalk and cheese," said Professor Nick Graham of Lancaster University.
"The ratless islands are full of birds, they are noisy, the sky is full and they smell – because the guano that birds deposit on the island is very pungent. from sea, this study revealed that rats disrupt a healthy ecosystem that relies on seabird droppings, which fertilize the reefs surrounding the island.
The islands, seabirds, including fools, frigates, noddies, shearwaters and terns, travel hundreds of miles to feed in the ocean and deposit rich nutrients.
"These nutrients are leached on the reef", explains Professor Graham
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Nick Graham
Mad-like seabirds nest much more abundantly on rat-free islands
He and his team were able to trace the source of these nutrients to the fish that seabirds fed by badyzing the algae and sponges that grew on the reef.
"We also found that reef fish adjacent to islands with seabirds grew faster and were larger for their age than fish on reefs near rat-infested islands," explains Professor Graham
]. more fish on rat-free reefs than on those around "shabby islands".
Why is it important?
Coral reefs cover less than 0.1% of the ocean surface, but are home to about one – third of the ocean 's biodiversity.
"Coral reefs are also extremely endangered," Graham said. "All those who care about extinctions and biodiversity need to worry about the future of coral reefs."
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Nick Graham
Coral reef systems are in "crisis" change
The reefs and their abundance of marine life provide livelihoods for millions of people around the world, so the decline of coral reefs is fast becoming a humanitarian crisis.
This team of researchers advocates eradication projects. world.
"Coral reef systems are in crisis because of climate change," Graham said. "And we are desperately trying to find ways to improve the resilience of coral reefs and enable them to cope with climate change." 19659005 "It's one of the clearest examples up here, where the eradication of rats will cause an increase in the number of seabirds and this will strengthen the coral reef."
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