Posted on Jul 23, 2017
A new documentary came out on Netflix last week. It’s called "Chasing Coral," and it looks at the impact of coral bleaching on reefs unless CO2 emissions are reduced. At World Heritage-listed reefs, including Australia’s Great Barrier Reef or Phoenix Islands protected Area in Kiribati, marine biologists have been working hard to reduce pollution and other stressors and boost resilience, says Fanny Douvere of UNESCO World Heritage Marine Program. But the record-breaking bleaching event that stretched from 2014 to last month made it clear that local management is no longer sufficient to protect these iconic rainforests of the sea. We are facing a global problem that demands global solutions says Douvere.
Last month, UNESCO released the first global scientific assessment of climate change impacts on World Heritage coral reefs. While international media has regularly reported on bleaching at the Great Barrier Reef, Fanny Douvere of UNESCO World Heritage Marine Program says that was just the tip of the iceberg. The El Nino and climate-fueled temperature spikes that were wiping out corals in Australia were also causing serious damage to reefs in Costa Rica, Mexico, France, the United States, the Philippines, and the Seychelles. And that is just the beginning of the story.
Dr. Mark Eakin, who runs the Coral Reef Watch program for the National Oceanic and Atmospheric Administration, and served as a chief scientific advisor for the NetFlix film says "living inside the tissues of this animal are microscopic algae, the plant or vegetable portion. These algae in their tissues are photosynthesizing, making energy from the sun just like leaves on trees or grass. And so these provide the primary food for the corals. The coral itself is clear so the light can get through to these algae. When the high temperatures cause a breakdown in the relationship between the coral animal and these algae, the corals are forced to spit them out into the water, because the algae actually start producing toxins that would kill the coral. So they spit these out. It leaves the tissue clear and you can see right through the clear tissue to the white skeleton underneath."
"Because corals are building a limestone skeleton," Eakin adds, they have actually ejected their food source. "They’re now starving; they’re injured but trying to survive. If the stress lasts long enough, then the coral will die and the whole thing will get covered over with mossy algae and look really ugly and start to break down very quickly."
It only takes a spike of 1 to 2 degrees, concludes Douvere "to threaten the health of coral reefs. As seawater heats up, coral animals expel the microscopic algae they rely on for energy. If heat stress lasts too long, and corals don’t reabsorb the algae, they can die. Reefs can recover from bleaching, but it takes 15 to 25 years, and with climate change causing more frequent heat waves, we are approaching the breaking point of these fragile systems."
The Daily Galaxy via National Geographic and WLRN