Tag: Coral bleaching

Bleaching risk on the rise for Great Barrier Reef corals

Global warming is likely to overwhelm corals'
Global warming is likely to overwhelm corals’ built-in thermal tolerance mechanisms within the next few decades, leading to more bleaching and mortality. Photo courtesy Dr. Peter Mumby.

Study identifies bleaching and mortality thresholds for imperiled coral reefs

Staff Report

The steady rise in ocean temperatures projected for the next few decades will put more and more corals at risk of bleaching, as the warm water simply overwhelms their thermal tolerance mechanisms.

Recent research along the Great Barrier Reef shows that corals have been able to survive past bleaching events because they were acclimated to warmer temperatures by being exposed to a pattern of gradually warming waters in the lead up to each episode. But global warming is likely to change that, the scientists said.

Before long, temperature increases of as little as 0.5 degrees Celsius may push many corals over the edge as the warm water causes them to expel the algae-like dinoflagellates that help keep them alive and give them their color.

Lead author Dr. Tracy Ainsworth from Coral CoE said  bleaching is like a marathon for corals.

“When corals are exposed to a pre-stress period in the weeks before bleaching, as temperatures start to climb, this acts like a practice run and prepares the coral. Corals that are exposed to this pattern are then less stressed and more tolerant when bleaching does occur,” Ainsworth said. Continue reading “Bleaching risk on the rise for Great Barrier Reef corals”

Global warming kills a third of Great Barrier Reef’s corals

Similar mortality expected in other tropical oceans

Dead and dying staghorn co ral , central Great Barrier Reef in May 2016. Credit: Johanna  Leonhardt
Dead and dying staghorn coral, central Great Barrier Reef in May 2016. Photo by Johanna Leonhardt.
Great Barrier Reef mortality map
Map of mortality estimates on coral reefs along 1100km of the Great Barrier Reef. Map courtesy ARC Centre of Excellence for Coral Reef Studies at James Cook University.

Staff Report

For years, scientists have warned that global warming threatens to decimate the world’s coral reefs within our lifetimes and this week, the dire warnings played out in Australia, where new surveys showed that more than a third of the corals along the Great Barrier Reef died in the past few months after an extensive coral bleaching episode.

“We found, on average, that 35 percent of the corals are now dead or dying on 84 reefs that we surveyed along the northern and central sections of the Great Barrier Reef, between Townsville and Papua New Guinea,” said Professor Terry Hughes, director of the ARC Centre of Excellence for Coral Reef Studies at James Cook University.

Australian scientists have closely tracked the status of reefs along their coastline for the past few months as it became evident that this year’s strong El Niño would raise ocean temperatures above the limit of what most corals species can survive, and the latest survey results confirm their worst fears. In a press release, the researchers said the impacts are still unfolding along the 2,300-long reef, with the worst damage to the central and northern sections. Continue reading “Global warming kills a third of Great Barrier Reef’s corals”

Climate: Heat-adapted corals not immune to bleaching

Intertidal Acropora corals exposed to air at low tide.
Intertidal Acropora corals exposed to air at low tide. Photo courtesy Dr. Verena Schoepf.

A matter of degrees …

Staff Report

Even corals living in some of the warmest ocean waters on the planet are susceptible to bleaching and heat stress, according to Australian researchers who studied unique tidal species in the Kimberley region.

When the water gets too warm, it breaks down the symbiosis between coral and their zooxanthellae (the microscopic plants which gives coral most of its colour), which can be fatal for the coral.

In the new study by scientists at the ARC Centre of Excellence for Coral Reef Studies said they were surprised to find that corals around the Kimberley region in north Western Australia are just as sensitive to heat stress and bleaching as their counterparts from less extreme environments elsewhere. Continue reading “Climate: Heat-adapted corals not immune to bleaching”

NOAA says coral reefs worldwide hit by bleaching

Extensive stand of severely bleached coral at Lisianski Island in the Papahanaumokuakea Marine National Monument in Hawaii, documented during an August 2014 NOAA research mission. (Credit: NOAA).
Extensive stand of severely bleached coral at Lisianski Island in the Papahanaumokuakea Marine National Monument in Hawaii, documented during an August 2014 NOAA research mission. (Credit: NOAA).

Up to 95 percent of U.S. coral reefs may be affected

Staff Report

Global warming is causing global coral bleaching, ocean scientists said today, confirming that rising ocean temperatures are resulting in massive and widespread impacts to reefs around the world.

“The coral bleaching and disease, brought on by climate change and coupled with events like the current El Niño, are the largest and most pervasive threats to coral reefs around the world,” NOAA’s Coral Reef Watch coordinator, Mark Eakin, said in a statement. Continue reading “NOAA says coral reefs worldwide hit by bleaching”

Climate: Coral reefs taking a big hit this year

A diverse coral reef in the U.S. Virgin Islands. PHOTO BY CAROLINE ROGERS/USGS.
Coral reefs in the Caribbean, like this one in the U.S. Virgin Islands, are at risk of bleaching as global warming heats up the world’s oceans. Photo by Caroline Rogers/USGS.

Warm oceans leading to widespread reef bleaching

Staff Report

FRISCO — Ocean researchers have updated their warnings of potential coral reef bleaching based on unusually warm ocean temperatures across the north Pacific, equatorial Pacific, and western Atlantic oceans this summer.

Scientists with NOAA’s coral reef watch say they expect  bleaching of corals on Northern Hemisphere reefs through October, potentially leading to the death of corals over a wide area and affecting the long-term supply of fish and shellfish.

“The bleaching that started in June 2014 has been really bad for corals in the western Pacific,” said Mark Eakin, NOAA Coral Reef Watch coordinator. “We are worried that bleaching will spread to the western Atlantic and again into Hawaii.” Continue reading “Climate: Coral reefs taking a big hit this year”

NOAA reports major coral bleaching in 2014

Hawaii bleaching the worst on record

Coral reefs experienced major heat stress in 2014. Map courtesy NOAA Climate.gov – Dan Pisut.

Staff Report

FRISCO — Even without a surge of El Niño ocean heat, there was widespread coral bleaching across parts of the Pacific Ocean and the Caribbean this past summer.

Reefs in the Florida Keys saw their worst bleaching episode since 1997-1999, when a major El Niño was followed by strong La Niña conditions, NOAA scientists reported recently. The surprising intensity of bleaching across multiple ocean basins in 2014 has scientists wondering what to expect in 2015, when El Niño is forecasted to finally develop. Continue reading “NOAA reports major coral bleaching in 2014”

Global warming: Study maps coral reef vulnerability

Global warming threatens coral reef diversity. Photo courtesy NOAA.

74 percent of world’s reefs could see annual bleaching events by 2035

By Summit Voice

FRISCO — Using the latest data from the upcoming IPCC climate assessment, ocean researchers have concluded that about three-quarters of the world’s coral reefs could face annual bleaching events in just a short 30 years, and they’ve mapped out which areas will be hit first.

“This study represents the most up-to-date understanding of spatial variability in the effects of rising temperatures on coral reefs on a global scale,” said researcher Serge Planes, Ph.D., from the French research institute CRIOBE in French Polynesia. Continue reading “Global warming: Study maps coral reef vulnerability”