Each year, the worlds coral reefs are shrinking at an increasingly frightening pace. Scientist have been trying to figure out how to protect reefs through different methods such as coral frag farming, reducing agricultural run-off, and killing species that are causing intensive damage to reef systems.
Now, scientists have come up with a brand new idea that could potentially be a major player in saving reefs near tropical islands, kill all the rats.
Studying the Chagos Archipelago in the Indian Ocean, the researchers found a surprising link between invasive rats on the island, the local seabird populations, and the health of the nearby reefs. They realized that the introduction of rats have decimated the local bird populations and is impacting the health of the reefs.
Published in Nature, The study outline that it is estimated that invasive predators like rats, which feed on bird eggs and chicks, have hugely impacted bird populations on about 90 percent of the world’s tropical islands, but this is the first time rats have been identified as the enemies of reefs too.
“Seabirds are crucial to these kinds of islands because they are able to fly to highly productive areas of open ocean to feed. They then return to their island homes where they roost and breed, depositing guano – or bird droppings – on the soil,” Professor Nick Graham of Lancaster Universtiy explained in a statement.
“This guano is rich in the nutrients, nitrogen and phosphorus. Until now, we didn’t know to what extent this made a difference to adjacent coral reefs.”
The researchers decided to survey the Chagos Islands as they were the perfect place to carry out the study as 18 of the 55 islands are rat-free wile the others have been infiltrated by black rats.
By examining soils, algae, and fish numbers from six infested islands and six rat-free ones they found that the devastation caused by the rats didn’t just stay on the islands but spread out into the surrounding seas too.
The rat-free islands had more abundant bird life, and the nutrients from their guano made the soil rich in nitrogen that filtered its way into the sea, providing food for the abundance of life including sponges, algae, and fish that live on the coral reefs. The team estimated that bird population densities are 800 times higher and fish populations 50 percent higher on these islands that did not have rats.
They also found that the grazing of algae on reefs of the rat-free islands was much higher, which is vital to helping clear the dead coral from the reef and prove a stable base for new coral to grow on.
On the rat-infested islands, the reefs and their inhabitants were in much worse shape as show the opposite effect that was seen on islands with no rats.
The researchers hope that by identifying this unusual chain of events, it may help in the fight for coral reefs around the world. They estimate the cost of exterminating the infested islands of the Chagos Archipelago at around $2-3 million, but as we haven’t found a way yet of protecting the world’s reefs against the impact of climate change, we need to carry out all measures to protect reefs so the amount is not significant when looking at the bigger picture.