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The extermination of black rats on the tropical islands is the best way to help coral reefs, including their fish, established an international team of scientists
The extermination of rats should therefore be an urgent conservation priority. Scientists have studied tropical ecosystems in the remote islands of the Indian Ocean to discover how rats impact on surrounding reefs. They compared islands with and without rats.
Their findings – published in the last issue of the journal Nature – confirmed that rats decimate seabirds, but also damage the ecology of the coral reefs that surround and protect the islands.
"Rats on the islands are reducing fish life and coral reef health," said Dr. Nicholas Graham, author of the article, at the Open Forum EuroScience of Toulouse. The study was conducted at the Chagos Archipelago in the Indian Ocean.
The islands were a perfect "laboratory", some were rat-free, while others were infested with black rats – allegedly introduced in the late 1700s and early 1800s. [19659008] The free island, the sky is full of birds, it's noisy and it smells, since their guano is so spicy, said Dr. Graham. The islands with rats are much quieter, with almost no seabirds: rodents eat seabird eggs, chicks and sometimes adult birds. "The difference is like chalk and cheese, with thousands of seabirds in the hectare [on rat-free islands] where there are rats," said Dr. Graham. The lack of birds was expected. What was more surprising was the dramatic impact of their excrement on adjacent coral reefs.
Huge pressure
The birds were feeding off, resting on the islands and fertilizing them with rich fish excrement, with a good balance of nitrogen and phosphorus. These nutrients flow at sea and benefit the fish of the coral reefs
Most of the world's coral systems are under enormous pressure due to global warming.
The size of this fertilizing effect surprised scientists, he said. The fish around the ratless islands grew faster and was more abundant. Coral reefs around the "birdy islands" have about 50 percent more fish biomass than those around the "islands".
Scientists have calculated that seabirds, such as terns and noddies, lose 251 times more nitrogen per hectare. islands only on islands infested with rats. Dr. Aaron MacNeil, of Dalhousie University, Nova Scotia, Canada, said the rat slaughter is an effective way to help coral reefs. change. "We knew that seabirds had a great influence on the islands, but they did not know they were influencing coral reefs. The level of productivity has been amazing, "said Dr. Graham, who insisted that" bird islands "are what the islands should be.
Unfortunately, 90% of the world's islands have been decimated invading species such as rats, mice and cats.It is possible to reverse this trend
The eradication of rats has been completed on 580 islands worldwide.Gr. Chagos islands of black bird-killer rats would cost 2 or 3 million dollars.
Many islands around Ireland and the United Kingdom have rats that could benefit from "said Dr. Graham, but after docking boats on the island should be carefully controlled so that the rats do not return.
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