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CAPTAIN COOK, Hawaii – At the edge of an ancient lava flow where jagged black rocks reach the Pacific, oversized little houses overlook the calm, blue waters of Papa Bay on Big Island, Hawaii – without tourists or hotels. Here, one of the most abundant and dynamic coral reefs grows just below the surface.
Yet even this remote shoreline, far removed from the impact of sunscreen, trampling feet and industrial sewage, is already showing the first signs of a catastrophic coral season in Hawaii.
Just four years after a major sea heat wave killed nearly half of the coast's corals, federal researchers predict that a new wave of hot water will provoke one. the worst coral bleaching in the region.
"In 2015, we reached temperatures we had never recorded in Hawaii," said Jamison Gove, oceanographer at the National Oceanic and Atmospheric Administration. "What is really important – or alarming, probably more appropriate – about this event, is that we have previously followed the evolution of our current situation in 2015."
Researchers using high-tech equipment to monitor Hawaii's reefs are seeing the first signs of bleaching in Papa Bay and elsewhere caused by a sea heat wave that has pushed temperatures to record highs for months . The months of June, July and August have all experienced the warmest ocean temperatures ever recorded around the Hawaiian Islands. Until September, ocean temperatures are lower than those observed in 2015.
Forecasters predict that high temperatures in the north Pacific will continue to inject heat into Hawaiian waters until October.
"The temperatures have been hot for quite a long time," said Gove. "It's not just the temperature, but the length of time that the ocean temperatures stay warm."
Ocean temperatures are not uniformly warm across the state, noted Gove. Local wind patterns, currents and even features on the land can create hot spots in the water.
"There are things like two giant volcanoes on the big island blocking the prevailing trade winds," making the west coast of the island, where Papa Bay is located, one of the hottest parts of the island. State, said Gove. He said to expect a "serious" coral bleaching in these places.
"This is common, whitening 100% of most corals," said Gove. And many of these corals are still recovering from the bleaching of 2015, which means they're more susceptible to heat stress.
According to NOAA, the heat wave originated from a persistent low pressure climate regime between Hawaii and Alaska, characterized by weak winds that could otherwise mix and cool surface waters across much of the North Pacific Ocean. . The cause of this is unclear: this could reflect the usual chaotic motion of the atmosphere, or could be related to the warming of the oceans and other effects of climate change caused by the atmosphere. ;man.
Beyond this event, ocean temperatures will continue to rise in the coming years, Gove said. "There is no doubt that global climate change is contributing to what we are going through," he said.
For corals, warm water is synonymous with stress, and prolonged stress kills these creatures and can leave reefs in shambles.
Bleaching occurs when stressed corals release algae that provide them with essential nutrients. This seaweed also gives color to the coral. So, when it is expelled, the coral becomes white.
Coral reefs are vital around the world because they are not only a habitat for fish – the base of the marine food chain – but also a food and medicine for humans. They also create an essential shoreline barrier that separates large ocean swells and protects densely populated shorelines from storm surges during hurricanes.
In Hawaii, reefs are also an important part of the economy: tourism is developing mainly through coral reefs that contribute to the creation and protection of iconic white sand beaches, offer snorkeling and diving sites and help to form waves that attract surfers from around the world.
Gove said the researchers had a technological advantage for monitoring and understanding money laundering this year, data that could help save the reefs in the future.
"We are trying to track this event in real time via satellite, which is the first time this has happened," said Gove.
In the remote bay of Papa Bay, most corals have recovered after the bleaching of 2015, but scientists are worried that they will not perform as well this time around.
"Almost all the species we monitor are suffering at least a little whitening," said ecologist Greg Asner, director of the Center for Global Discovery and Conservation Science of Arizona State University, after a dive into the bay at the beginning of the month.
Asner told Associated Press that sensors showed the bay was about 3.5 degrees Fahrenheit above normal for this time of year.
It uses advanced aircraft-based imaging technologies, satellite data, underwater sensors and public information to provide national and federal researchers like Gove with the information they need.
"What's really important here is that we take these measurements (under water), connect them to the data of our aircraft, and then connect them back to the satellite data", said Asner. "It allows us to zoom in to get an overview so we know the truth about what's going on here."
Scientists will use this information to research, among other things, why some species of corals are more resistant to heat stress. Some of the latest research suggests that a slow exposure of coral to heat in the labs can condition them to withstand hotter water in the future.
"Once the heat wave is over, we will have a good map to plan restoration efforts," Asner said.
Hawaii residents, such as Cindi Punihaole Kennedy, contribute to educating tourists. Punihaole Kennedy is director of Kahalu's Bay Education Center, a non-profit organization created to help protect Kahalu's bay, a popular snorkeling site located near the tourist hub of Kailua-Kona. , on the big island.
The bay and the surrounding beach park are home to more than 400,000 visitors a year, she said.
"We share with them what to do and what not to do when they enter the bay," she said. "For example, avoid walking on the corals or feeding the fish."
The bleaching and death of corals was widespread in the region in 2015.
"It was devastating for us to not be able to do anything," said Punihaole Kennedy. "We just watch the corals die."
– The Associated Press
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