Get Regular Updates!
Search

Earth

image|

Bernard Dupont, Wikimedia Commons

How rats are killing our coral reefs

How rats are killing our coral reefs

It’s an invasion of rats! Some remote islands are crawling with these rodents, and even the coral reefs are suffering from it.

How rats are killing our coral reefs

Rats eat pretty much anything, and that’s a problem for coral reefs.

On islands, rats feed on lots of things, including bird eggs, chicks and even adult birds. Now, a new study by researchers from UWA, Lancaster University, ARC Centre of Excellence for Coral Reef Studies and Dalhousie University found that the rats’ appetite for birds spells serious trouble for surrounding coral reefs.

But wait, what do rats’ dining habits have to do with coral reefs? To answer this question, the researchers studied a group of remote tropical islands in the central Indian Ocean called the Chagos Islands. Some of these islands were inhabited in the 1800s but not any more, except for black rats, a legacy from their past human occupation.

View Larger
Image|Charles and Anne Sheppard/ University of Warwick
Rats may have done some serious damage to Chagos Island wildlife, both on and offshore

Back in 2015, researchers compared islands infested with rats with islands where no human or rat had ever set foot or claw. They found clear evidence that rats were bad news for other island life.

The rat, the bird and the reef

“At Chagos, rats have decimated native bird populations by feeding on eggs and chicks and preventing nesting on some islands, but on islands where there are no rats, there are huge numbers of seabirds,” says Shaun Wilson, co-author of the new study and researcher at the Department of Biodiversity, Conservation and Attractions.

View Larger
Image|Shaun Wilson
On islands with rats, chicks make easy prey for the hungry rodents

It turns out that rats feasting on birds sets off a devastating chain of events. When there are fewer birds around, there is less poop on the soil, which means less nitrogen and other nutrients available on the islands. Some of these nutrients also leach out of the island soils into the sea, where they benefit marine organisms, like macroalgae, filter-feeding sponges, turf algae and fish.

“The bird droppings nourish island soils and can be detected in coastal plants. We found that nutrients from bird droppings can also be found in seaweed, sponges and fish on reefs that are adjacent to islands where there are no rats and high bird numbers,” Shaun says.

Video|Daily Mail
There are more fish in the waters near islands with no rats. Some species, such as the parrotfish, help maintain healthy coral ecosystems

Researchers also found that there are more fish in the waters near islands where there were no rats and lots of birds. Fish have an important job keeping coral reefs healthy and helping them recover from disturbances. For example, some fish eat seaweeds, removing them from the reef and creating space for corals to grow. Others, like parrotfish, remove both seaweed and a chunk of hard reef when they feed. This provides a nice clean surface for new corals to settle.

New research shows that rats have a negative impact on the coral reef's ecosystem, and it is mainly their appetite for birds that puts coral reefs in danger.
“Introduced pests, like rats, can have a detrimental effect on both the terrestrial and marine environment"

So, fewer rats means more birds, more birds means more fish and more fish means healthier reefs.

Plans for the future: “kill them all”

The findings of this new study provide convincing evidence that rats are not only a pest for us humans but also for birds, fish and coral reefs.

“Our research highlights that introduced pests, like rats, can have a detrimental effect on both the terrestrial and marine environment and may compromise the health of coral reefs, which are already threatened by global warming,” says Shaun.

“Hence the need to eradicate rats from islands. This has been done successfully in a number of places around the globe and could be extended to islands in the Chagos Archipelago,” he adds.

View Larger
Islands without invasive black rats are lively with plant & bird life

We know the rats need to go, and we hope their days of feasting on bird eggs are numbered. But it’s up to authorities to take action. The Chagos Islands are part of the British Indian Ocean Territory, and according to Shaun, there are ongoing efforts to get these rats off the map.

Tracking WA Science VIDEO

Republish

Creative Commons Logo

Republishing our content

We want our stories to be shared and seen by as many people as possible.

Therefore, unless it says otherwise, copyright on the stories on Particle belongs to Scitech and they are published under a Creative Commons Attribution-NoDerivatives 4.0 International License.

This allows you to republish our articles online or in print for free. You just need to credit us and link to us, and you can’t edit our material or sell it separately.

Using the ‘republish’ button on our website is the easiest way to meet our guidelines.

Guidelines

You cannot edit the article.

When republishing, you have to credit our authors, ideally in the byline. You have to credit Particle with a link back to the original publication on Particle.

If you’re republishing online, you must use our pageview counter, link to us and include links from our story. Our page view counter is a small pixel-ping (invisible to the eye) that allows us to know when our content is republished. It’s a condition of our guidelines that you include our counter. If you use the ‘republish’ then you’ll capture our page counter.

If you’re republishing in print, please email us to let us so we know about it (we get very proud to see our work republished) and you must include the Particle logo next to the credits. Download logo here.

If you wish to republish all our stories, please contact us directly to discuss this opportunity.

Images

Most of the images used on Particle are copyright of the photographer who made them.

It is your responsibility to confirm that you’re licensed to republish images in our articles.

Video

All Particle videos can be accessed through YouTube under the Standard YouTube Licence.

The Standard YouTube licence

  1. This licence is ‘All Rights Reserved’, granting provisions for YouTube to display the content, and YouTube’s visitors to stream the content. This means that the content may be streamed from YouTube but specifically forbids downloading, adaptation, and redistribution, except where otherwise licensed. When uploading your content to YouTube it will automatically use the Standard YouTube licence. You can check this by clicking on Advanced Settings and looking at the dropdown box ‘License and rights ownership’.
  2. When a user is uploading a video he has license options that he can choose from. The first option is “standard YouTube License” which means that you grant the broadcasting rights to YouTube. This essentially means that your video can only be accessed from YouTube for watching purpose and cannot be reproduced or distributed in any other form without your consent.

Contact

For more information about using our content, email us: particle@scitech.org.au

Copy this HTML into your CMS
Press Ctrl+C to copy

We've got chemistry. Want something physical?