Scientists Reveal the Epic Ocean Voyage of Coral Reef Larvae

When most people think of coral, they think of the beautiful tropical reefs that thrive in the Caribbean and along Australia. These corals are seen as stationary--immovable and part of the landscape. Yet corals are animals and, like many other seafaring creatures, are mobile when they're younger. Now, scientists have used computer simulations to reveal the epic, ocean-spanning journeys travelled by tiny coral larvae through the world's seas.

As sea temperatures rise and pollution increases, corals are under threat from disease, bleaching and a host of other factors. That's why it's more important than ever to understand how these corals could potentially respond to these changing conditions. In fact, it's very likely that corals will shift over time as environmental conditions shift.

"Dispersal is an extremely important process for corals," said Sally Wood, one of the researchers, in a news release. "As they are attached to the seafloor as adults, the only way they can escape harmful conditions or replenish damaged reefs is by releasing their young to the mercy of the ocean currents."

In order to find out exactly where these corals might end up, the researchers employed the Connectivity Modeling System (CMS). This allowed them to identify the billions of paths taken by corals and find out exactly where ocean currents might take coral larvae.

"Simulating an unprecedented number of mass spawning events from all known shallow reefs in the global ocean proved essential to identifying critical long dispersal distance events that promote the establishment of new coral colonies," said Claire Paris, one of the researchers, in a news release. "What we found using the CMS are rare long distance dispersers that are thought to contribute to species persistence in isolated coral reefs, and to geographic range shifts during environmental changes."

So where exactly did the larvae go? The majority of them settled close to home. Yet there were others that travelled almost the entire width of the Pacific Ocean. When considered over multiple generations, this means that corals could cross entire ocean basins, using islands and coastlines as "stepping stones." This means that corals may have a chance to move to areas that are more hospitable to their survival.

Currently, researchers are planning to study these corals further. While travelling the distance is possible, these larvae still have to overcome a host of difficulties when they settle on a location; they have to find a proper surface on which to live and compete fiercely for space to thrive and grow. Even so, the new research could allow scientists to better predict exactly where corals might be found in the future.

The findings are published in the journal Global Ecology and Biogeography.