Scientists Say Coral Reefs Are Moving Away from Tropical Waters Due to Climate Change

Once synonymous with tropical destinations, vibrant corals are now found growing more frequently in cooler regions farther away from equatorial waters, according to new research published in the journal Marine Ecology Progress Series. A team of researchers from the Bigelow Laboratory for Ocean Sciences worked alongside an international team comprised of 17 different institutions from six different countries to discover the newfound trend, mostly studying the corals found in the wild near French Polynesia. Together, the teams comprised a database of information dating back to 1974, finding that young corals on tropical reefs have declined by 85 percent. Meanwhile, in the same span of time, it seems that the amount of coral specimens thriving on subtropical reefs have doubled.

"Climate change seems to be redistributing coral reefs, the same way it is shifting many other marine species," Nichole Price, a senior research scientist at Bigelow Laboratory for Ocean Sciences and lead author of the paper, said in a statement. "The clarity in this trend is stunning, but we don't yet know whether the new reefs can support the incredible diversity of tropical systems."​

Because much of the ocean has experienced some form of warming due to climate change, researchers found that corals are growing in cooler waters as far as 35 degrees north and south of the equatorial stretch of ocean where they've historically thrived. This change may also lure other ocean wildlife, including fish and other aquatic species, to new ecosystems away from tropical regions. Not all coral is able to adapt in new locations, however, because only some coral larvae can swim farther and drift in currents to new areas away from traditional breeding grounds.

"We are seeing ecosystems transition to new blends of species that have never coexisted, and it's not yet clear how long it takes for these systems to reach equilibrium," Satoshi Mitarai, a co-author of the study and a professor at the Okinawa Institute of Science and Technology Graduate University, said in the same press release. "The lines are really starting to blur about what a native species is, and when ecosystems are functioning or falling apart."

While the study reports promising findings for those worried about the gradual decline in healthy ocean corals, researchers are unsure if all of the species that enable corals to thrive will be able to migrate as well. The teams behind this sweeping study hope that other scientists will add to their newly created database in the future. "So many questions remain about which species are and are not making it to these new locations, and we don't yet know the fate of these young corals over longer time frames," Price said. "The changes we are seeing in coral reef ecosystems are mind-boggling, and we need to work hard to document how these systems work and learn what we can do to save them before it's too late."