FORT LAUDERDALE, Fla. (AP) — Some coral reefs in the Florida Keys are losing color weeks earlier than usual this summer due to record high water temperatures, meaning they’re under stress and their health may be at risk, federal scientists say.
The corals should be vibrant and colorful this time of year, but turn white quickly, said Katey Lesneski, research and monitoring coordinator for Mission: Iconic Reefs, which the National Oceanic and Atmospheric Administration launched to protect Florida’s coral reefs.
“The corals are pale, it seems like the color is draining,” said Lesneski, who has spent several days on the reefs over the past two weeks. “And some people are stark white. And there is more to come.”
Scientists with NOAA this week raised their coral bleaching alert to Alert Level 2 for the Keys, their highest heat stress level of the five. That level is reached when the average water surface temperature is about 1.8 degrees Fahrenheit (1 degree Celsius) above the normal maximum for eight consecutive weeks.
Surface temperatures around the Keys average about 91 degrees (33 degrees Celsius), well above the normal mid-July average of 85 degrees (29.5 degrees Celsius), said Jacqueline De La Cour, operations manager of NOAA’s Coral Reef Watch program. Previous alert level 2s were reached in August, she said.
Coral reefs are made up of small organisms that are connected to each other. The reefs get their color from the algae that live in them and are the food of the corals. When the temperature gets too hot, the coral expels the algae, leaving the reefs looking white or bleached. That doesn’t mean they’re dead, but the corals can starve and are more susceptible to disease.
Andrew Bruckner, research coordinator at the Florida Keys National Marine Sanctuary, said some coral reefs started showing the first signs of bleaching two weeks ago. Then in recent days some reefs lost all their color. That had never been registered before August 1. The peak for bleaching usually falls in late August or September.
“We are at least a month ahead, if not two months,” Bruckner said. “We’re not at the point where we’re seeing any mortality… from bleaching. It’s still a small number that are all white, certain species, but it’s much sooner than we expected.”
Still, it is difficult to predict what will happen for the rest of the summer, according to De La Cour and Bruckner. While water temperatures can continue to rise — which can be devastating — a tropical storm or hurricane can cause the water to swirl and cool. Dusty air from the Sahara Desert moving across the Atlantic Ocean and settling over Florida can dampen the sun’s rays, lowering temperatures.
Due to climate change and other factors, the Keys waters have lost 80% to 90% of their coral over the past 50 years, Bruckner said. That not only affects the marine life that depends on the reefs for survival, but also people – coral reefs are a natural buffer against storm surges from hurricanes and other storms. There is also an economic impact as tourism through fishing, diving and snorkeling relies heavily on coral reefs.
“People get in the water, let’s fish, let’s dive — that’s why protecting Florida’s coral reef is so important,” De La Cour said.
Both scientists said it’s not “all doom and gloom”. A 20-year, large-scale effort is underway to rebuild Florida’s coral to about 90% of where it was 50 years ago. Bruckner said scientists are growing corals that are more resistant to the heat and using simple things like shade covers and underwater fans to cool the water to help them survive.
“We’re looking for answers and we’re trying to do something, rather than just look away,” Bruckner said.
Growing corals could promote the heat resistance of future generations of the animals, said Jason Spadaro, coral reef restoration program manager for Mote Marine Laboratory & Aquarium in Sarasota, Florida. That could be vital to saving them, he said.
Spadaro and others who have visited the corals said they have noticed that the coral bleaching is worse in the lower Keys than in the more northerly parts of the area. The Keys have had some bad years in the past, but this year it’s “really aggressive and it’s really persistent,” he said.
“It will be a tough year for the reef. It underscores the need to continue this important work,” he said.
The early bleaching occurs during a year when water temperatures rise earlier than normal, said Ross Cunning, a research biologist at Shedd Aquarium in Chicago. The Keys are experiencing water temperatures in excess of 32 degrees Celsius, which would normally not occur until August or September, he said.
The hot water could lead to a “disastrous bleaching event” if it doesn’t subside, Cunning said.
“We are now seeing temperatures that are even higher than what we normally see at peak times, which makes this particularly scary,” Cunning said.
De La Cour said she has no doubt that the warming waters are caused by human-induced global warming and that this needs to be fixed for coral to survive.
“If we don’t reduce the greenhouse gas emissions that we emit and reduce the greenhouse gases that are already in the atmosphere, we will create a world where coral reefs cannot exist no matter what we do,” she said.
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Whittle reported from Portland, Maine.
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