great barrier reef

Pesticides In The Great Barrier Reef

November 7, 2019 By EarthWise Leave a Comment

Australia’s Great Barrier Reef is one of the greatest natural wonders in the world and it has been under siege by warming waters and ocean acidification. Widespread coral bleaching has damaged or destroyed large portions of the 1,400-mile long coral reef system. But the effects of climate change are not the only threat to the reef. Pesticides found in waterways that flow into the Great Barrier Reef are another serious problem.

According to a new study by the University of Queensland, the combined toxicity of 22 of the most common pesticides that flow into the Reef are not meeting pollution reduction targets.

Different pesticides affect different organisms. Herbicides affect organisms that photosynthesize such as seagrass, corals, mangroves, and algae. Insecticides affect insect larvae in freshwater, and crustaceans such as crabs, prawns, and lobsters. Previous assessments have only examined individual pesticides and only for limited times. The new study has utilized a methodology that estimates the combined toxicity of multiple pesticides found in the waterways that discharge into the Reef and does it for the entire wet season.

The research revealed that the pesticide reduction target set in the Australian Government’s Reef 2050 Water Quality Improvement Plan is not being met. Only one natural resource management region – the Cape York region – was found to be meeting its target.

By having estimates of the risk posed by pesticides in the various regions and individual waterways, governments, farmers, and conservationists can see which areas pose the greatest risk and where to maximize efforts. Stakeholders have to come together to reduce pesticide concentrations through better management practices and by using less toxic pesticides.

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High pesticide concentrations continue to enter Great Barrier Reef

Photo, posted July 29, 2010, courtesy of Kyle Taylor via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A New Kind Of Coral Nursery

October 22, 2019 By EarthWise Leave a Comment

Coral reefs around the world are struggling from warming waters and increasing ocean acidification driven by excess carbon dioxide. Many of the world’s greatest reefs – such as Australia’s Great Barrier Reef – have seen steep declines over the past decade.

But apart from the global environmental threat, reefs also are often damaged by various marine accidents such as ships grounding on them. Such events can severely damage a reef and scatter countless small coral fragments onto the seafloor. These small pieces of coral are not actually dead; they can continue on with their lives if they are relocated to a suitable environment such as a coral nursery.

Coral nurseries are generally small installations that allow coral fragments – typically pieces about 4 inches in length – to recover from their reef breaking up and to grow until they are large enough for conservation managers to replant them into reefs that need them. This strategy works well in places where corals grow relatively quickly – such as Florida and the Caribbean – but not as well in places where coral grows more slowly, such as Hawaii.

Recently, coral experts at the National Oceanic and Atmospheric Administration working with mechanical engineering students at the University of Hawaii have developed a new type of coral nursery that can save fully formed coral colonies as opposed to small coral fragments.

The nurseries are large, carefully designed structures that can be loaded up with corals that have become detached from their reefs. Some of these new structures were installed in the waters of Oahu in the summer of 2018 and were populated with corals. The relocated corals, which would have otherwise died, are now recovering nicely in their new coral daycare centers and will soon be replanted back into the reef.

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NOAA Develops A New Type of Coral Nursery

Photo, posted July 29, 2010, courtesy of Kyle Taylor via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Another Problem For Coral Reefs

April 5, 2019 By EarthWise Leave a Comment

Coral reefs around the world have been suffering in recent years from warming ocean temperatures as well as from increasing ocean acidification. Corals are very sensitive organisms that can only tolerate relatively slight changes in their environment. Thus, the majority of reef-building corals are found in tropical and subtropical waters with favorable conditions.

New research has confirmed that drastic changes in ocean salinity from, for example, severe freshwater flooding, provoke similar stress responses in corals as the heating that has resulted in freshwater bleaching and, eventually, coral death.

The coast of northeast Queensland in Australia has experienced abnormal monsoon-related freshwater flooding that caused extreme and sudden changes in the ocean salt concentration. In places, nearshore reefs were exposed to water with only half the normal ocean salinity. The result has been a shock response in corals that prevents normal cell function. Unlike their response to heat stress, corals exposed to reduced salinity experience a complete collapse of their internal cellular protein balance.

The central Great Barrier Reef has actually been relatively free from mass thermal bleaching events this Australian summer, but many coastal reefs instead have been battling dramatic changes in water conditions as a result of massive plumes of floodwater.

The wild weather in Australia is undoubtedly associated with the changing climate and this new research shows that it is leading to yet another threat to the world’s coral reefs. With the frequency and severity of heavy rainfall and runoff events predicted to continue to increase over the next few decades, proactive measures to increase the resiliency of coral reefs are needed more than ever.

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Reduced salinity of seawater wreaks havoc on coral chemistry

Photo, posted December 12, 2010, courtesy of Gareth Williams via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Disease On Coral Reefs

February 19, 2019 By EarthWise Leave a Comment

The warming oceans have led to bleaching events in coral reefs around the world, but bleaching is not the only problem corals face. Disease outbreaks are also becoming more frequent, severe, and widespread.

Many factors are contributing to the problem, including pollution and nitrogen runoff from fertilizers and coastal sewer and septic systems. However, the key culprit is likely the steadily increasing ocean temperatures, which are the cause of coral bleaching. Elevated water temperatures can cause coral polyps to expel the algae that sustains them and gives them color.

According to scientists, bleaching makes corals more susceptible to illness. In the Caribbean, a coral disease hotspot, about 80% of coral cover has disappeared, largely from outbreaks of “white band disease”, so called because of a white band of dead tissue that forms in affected corals. Two crucial reef-building species, elkhorn and staghorn coral, are now nearing extinction in the regions. The reef extending along the Florida coastline is the third largest reef ecosystem in the world and nearly 35% of it has been lost to disease.

Estimates are that disease outbreaks have wiped out at least 6% of the corals on the Great Barrier Reef in Australia. In that region, diseases are more prevalent in areas where corals were damaged by fishing and other human activity because wounded coral provides an entry point for pathogens and bacteria.

In the face of climate change and mounting disease outbreaks, scientists are scrambling for solutions to stave off catastrophe. Assisting the migration of hardier coral species and breeding so-called “super corals” are among the strategies being pursued. It is unknown whether these and other forms of intervention can be used on a wide enough scale to really make a difference.

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As Disease Ravages Coral Reefs, Scientists Scramble for Solutions

Photo, posted November 29, 2012, courtesy of Robert Linsdell via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Is There Hope For Coral Reefs?

January 16, 2019 By EarthWise Leave a Comment

News about the world’s coral reefs has been relentlessly bad for a number of years. Warming, acidifying oceans have wreaked havoc with coral reefs leading to enormous losses. Nowhere have things been more dire than in Australia’s Great Barrier Reef. Coral bleaching events have been increasingly common and severe over the past two decades. In fact, only 7% of the Great Barrier Reef has escaped bleaching entirely since 1998.

While the future of the world’s coral reefs is very much uncertain as global heating continues, there is a recent bit of hopeful news. According to a study published in Nature Climate Change, the response of the Great Barrier Reef to the extreme temperatures in 2017 was quite different from that of the previous year in the aftermath of back-to-back bouts of coral bleaching.

Surprisingly, corals that bleached in 2016 but managed to survive were more resistant to the recurrence of hot conditions in 2017.

Many corals don’t survive bleaching events at all and, of course,those corals don’t bleach for a second time. But the surviving corals from the 2016 bleaching event were tougher species. As a result of bleaching, the mix of coral species on the reef is changing very rapidly. The net result was that there was less bleaching in 2017 even though the temperatures that year were even more extreme than in 2016.

There have now been four mass bleaching events on the Great Barrier Reef over the past 20 years and it is only a matter of time before another one occurs triggered by the next marine heatwave. Almost half of the corals on the northern two-thirds of the reef have been killed. But at least some of the reef is showing impressive survival skills.

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A glimmer of hope for the world’s coral reefs

Photo, posted November 29, 2012, courtesy of Robert Linsdell via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Heat-Resistant Corals

August 31, 2018 By EarthWise Leave a Comment

All over the world, coral reefs are being wiped out by rising sea temperatures brought about by climate change. When sea temperatures get too high, the symbiotic relationship between coral polyps and microscopic algae living within the coral breaks down and the coral either digests or expels the algae. The result is coral bleaching which weakens, and if it persists, kills the coral.

Can The Great Barrier Reef Be Saved?

August 17, 2017 By EarthWise

There have been many stories in the media about the ongoing environmental crisis at Australia’s Great Barrier Reef. Over the past two years, the reef has lost almost half of its coral because of bleaching events. Faced with this situation, the Australian government created the Reef 2050 Plan, a strategy to protect and maintain the reef through the year 2050.

Could Coral Reefs Be Wiped Out?

August 8, 2017 By EarthWise

A new study warns that coral reefs are in danger of disappearing forever. According to U.N. research, the world’s coral reefs could die out completely by mid-century unless carbon emissions are reduced enough to slow ocean warming.

Threats To Coral Reefs

May 12, 2017 By EarthWise

There has been much news recently about the growing bleaching events going on in the world’s coral reefs associated with ocean warming and acidification. The massive damage to Australia’s Great Barrier Reef is an ongoing tragedy.

The Great Barrier Reef

April 27, 2017 By EarthWise

According to a new paper published in the journal Nature, global warming has damaged huge sections of Australia’s Great Barrier Reef. The authors of the paper warn that the resilience of the reef – which is the world’s largest living structure – is waning rapidly.

Bleached And Dying

February 23, 2017 By EarthWise

Climate change is posing a major threat to the future of coral reefs. According to a recent United Nations-backed study, if swift action is not taken to curb greenhouse gas emissions, annual coral bleaching events will affect nearly all of the world’s coral reefs. And coral bleaching can result in serious coral mortality – as Australia’s Great Barrier Reef has recently illustrated.

[Read more…] about Bleached And Dying

Some Good News For Coral Reefs

August 12, 2016 By WAMC WEB

Most recent news about coral reefs around the world has been bad news. There has been unprecedented coral bleaching in places like Australia’s Great Barrier Reef. The effects of climate change – including warming temperatures and rising seas – as well as the recent El Niño event have led to damaged reefs across the globe.

Coral Bleaching On The Great Barrier Reef

May 9, 2016 By WAMC WEB

It was already well-known that coral bleaching was a serious problem in the Great Barrier Reef, but extensive aerial surveys and underwater dives have now revealed the shocking extent of the problem.

Natural World Heritage Sites

May 5, 2016 By WAMC WEB

Natural world heritage sites exemplify the world’s greatest areas of natural beauty, ecology, geology, and biodiversity. They are recognized internationally for their value as places with significance that is “so exceptional as to transcend national boundaries and be of common importance for present and future generations of all humanity.” Many of these areas also are a vital source of food, fuel, and water for rural communities, and provide a revenue stream for national economies through tourism and recreation. The livelihoods of some 11 million people are directly dependent on these areas.