Tag: Great Barrier Reef

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”

Australian scientists document massive coral bleaching along the Great Barrier Reef

Global warming impacts on reefs unfolding as projected

Great Barrier Reef coral bleaching 2016
Aerial surveys by Australian researchers shows that at least 40 percent of the Great Barrier Reef has been affected by bleaching. Photo courtesy ARC Centre of Excellence for Coral Reef Studies / Terry Hughes.

Staff Report

Global warming has been driving the worst and longest episode of coral reef bleaching on record, and the event is hitting the Great Barrier Reef especially hard. Australian scientists this week said their latest aerial surveys of more than 500 reefs show that the most pristine section of the Great Barrier Reef is currently experiencing the worst, mass bleaching event in its history, with the overwhelming majority of reefs being ranked in the most severe bleaching category.

Widespread coral reef bleaching started in 2014, even before El Niño kicked into high gear. As forecasts for this year’s El Niño became more certain, ocean scientists warned in advance that widespread bleaching, spurred by warm ocean temperatures, would occur. There’s plenty of research that enables scientists to project bleaching events, and last November, NOAA warned that reefs around the world would be affected this year. In February, NOAA announced that record and near-record ocean temperatures are prolonging the longest global coral die-off on record.

The latest data from the Australian researchers confirms all the projections and worst fears that global warming will likely decimate most coral reefs worldwide. That, in turn, could affect entire ocean ecosystems, since reefs are the nurseries of the seas.

“This has been the saddest research trip of my life,” said Prof. Terry Hughes, with Australia’s National Coral Bleaching Taskforce. “Almost without exception, every reef we flew across showed consistently high levels of bleaching, from the reef slope right up onto the top of the reef. We flew for 4,000 kilometers in the most pristine parts of the Great Barrier Reef and saw only four reefs that had no bleaching. The severity is much greater than in earlier bleaching events in 2002 or 1998,” Hughes said. Continue reading “Australian scientists document massive coral bleaching along the Great Barrier Reef”

Trouble ahead for the Great Barrier Reef?

A NASA satellite photo shows a slice of Australia's Great Barrier Reef.
A NASA satellite photo shows a slice of Australia’s Great Barrier Reef.

Ancient climate clues warn about impacts of modern human activities

Staff Report

FRISCO — Turbulent seas, loaded with sediment and nutrients at the end of the last ice age likely set back growth of the Great Barrier Reef by centuries, according to scientists who recently took a close look at the reef’s biological history.

The findings are important because those environmental conditions are similar to what the Great Barrier Reef is experiencing today as a result of human activities, including the controversial coal port dredging that’s seen as a huge threat to Australia’s cherished ocean landmark. Continue reading “Trouble ahead for the Great Barrier Reef?”

Environment: Top predatory fish needed to maintain balance in coral reef ecosystems


Australian study shows how recreational and commercial fishing affect reef health

Staff Report

FRISCO —Biologists have long known that removing key predators from the food chain has top-down impacts on ecosystems, and a new study by Australian researchers shows the same holds true for coral reefs. Fishing, they say, is having a big impact on the Great Barrier Reef.

The loss of species like coral trout and snappers has altered the balance and structure of the coral reef ecosystem, raising the number of herbivorous and small prey fish, the scientists concluded after comparing fish abundance in protected parts of the reef with other areas. Continue reading “Environment: Top predatory fish needed to maintain balance in coral reef ecosystems”

Environment: How to save the Great Barrier Reef

A section of the Great Barrier Reef photographed from the International Space Station.

Australian scientists offer common-sense plan to restore coral reef ecosystem

Staff Report

FRISCO — After a 40-year span when the Great Barrier Reef lost half its coral cover, and with global warming looming for the future, Australian scientists say fundamental changes are needed to protect the reef.

Better policies focusing on science, protection and conservation are the key, a team of leading researchers wrote this week in the journal Nature Climate Change, arguing that all the stressors on the Reef need to be reduced for it to recover. Continue reading “Environment: How to save the Great Barrier Reef”

Protected zones pay off for Great Barrier Reef

A NASA Earth Observatory view of the Great Barrier Reef.

Study shows rebound of coral trout in no-fishing zones

Staff Report

FRISCO — Long-term monitoring in the Great Barrier Reef ecosystem shows that marine protection pays off in a big way, as scientists said that coral trout biomass has more than doubled since the 1980s in the green zones.

The trout in the protected reserves are bigger and more abundant than those in fished “blue zones” of the Great Barrier Reef Marine Park, and they are also better able to cope with cyclone damage, according to a long-term study published today in Current Biology. Similar approaches may be beneficial for coral reefs around the world, the researcher concluded. Continue reading “Protected zones pay off for Great Barrier Reef”