When it comes to the world's coral reefs, the news these days is rarely good. Rising water temperatures, increasing acidification, mass tourism and plastic pollution pose threats to the planet's besieged reefs. However, every now and then good news comes.
One such example is a scientific report that coral reefs in the Eastern Tropical Pacific region have been resisting climate change better than expected. Scientists say reefs in the area have adapted well to heat stress, which is raising hope that reefs elsewhere can also survive a changing climate for decades to come.
An international team of researchers examined data on coral cover in an area stretching from Baja California to the Galapagos Islands for a period of more than four decades, between 1970 and 2014. During that time, various El Niño events, that brought unusually high temperatures, battered local reefs, leading to the death of symbiotic algae that coexist with corals. The results were episodes of massive bleaching that decimated the corals.
However, within 10 to 15 years, many of the local corals recovered. How they did it is still a mystery, as many corals elsewhere never recover from mass bleaching.
Scientists postulate that one reason could be that most local corals are pocilloporids, which reproduce at high speeds, so that after an episode of mass bleaching, the surviving corals can repopulate the area quickly. Local corals also support symbiotic algae species that are especially tolerant of high water temperatures. Additionally, some local areas of the ocean have thicker cloud cover or cooler water outcrop, helping corals survive and regenerate even at higher temperatures.
"The key to future reef survival may not be immunity to stress, but rather the ability to recover and grow back after stress," said James W. Porter, professor emeritus at the Odum School of Ecology. University of Georgia. "Discovering a large area of the tropics where the coral reefs stand firm is very rewarding."
Elsewhere around the tropics, many coral reefs have been experiencing changes in their environment less well, but even there not all hope has been lost yet. Some corals in other areas are also naturally better able to recover from bleaching episodes. Scientists say planting stressed reefs with hardier coral species could also help.