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Climate Resilient Microalgae | Earth Wise

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The plight of the world’s coral reefs has been a growing environmental crisis for many years.  Coral reefs provide sustenance and income to half a billion people, are major tourist attractions, protect coastlines, and are important centers of biodiversity.   And because of the warming climate as well as other effects of human activity, more than half of the world’s coral reefs are under stress.

The primary threat is coral bleaching, which is the disruption of the symbiotic relationship between coral polyps (which are tiny animals) and the heavily pigmented microalgae that live within the coral structures and provide most of the energy for the polyps. When corals are stressed, often because water temperatures are too high, they expel the microalgae within them.  The structures then become transparent, leaving only the white skeletal corals.  Bleached corals aren’t dead, but they are at great risk of starvation and disease until and unless new symbiont algae are acquired.

A new study by scientists at Uppsala University in Sweden investigated how different species of coral symbiont algae react to temperature stress.  They discovered differences among symbiont cells that enable the prediction of how temperature stress tolerant the cells are.  Such predictive ability could provide the means to identify and select more temperature-tolerant coral symbionts that could conceivably be introduced into coral host larvae in order to make corals more robust against climate change.

The research has a ways to go, but the new tools may help coral reef monitoring and increase the speed at which reef restoring efforts can create stocks of climate-resistant symbionts.

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Climate resilient microalgae could help restore coral reefs

Photo, posted September 28, 2009, courtesy of Matt Kieffer via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Training Corals To Tolerate Heat | Earth Wise

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When ocean water is too warm, corals expel the algae that lives in their tissues, which causes the coral to turn completely white.  This is called coral bleaching.   When this happens, the coral is not dead.  However, corals are dependent upon the symbiotic relationship with algae and if conditions don’t improve, they don’t let the algae back in and the corals will die.

According to the National Oceanic and Atmospheric Administration, between 2014 and 2017, around 75% of the world’s tropical coral reefs experienced heat stress severe enough to trigger bleaching.  For 30% of the world’s reefs, the heat stress was enough to kill the coral.

According to new research by the University of Miami published in the journal Coral Reefs, corals subjected to a stressful regimen of very warm water in the laboratory came to be more tolerant of high temperatures, offering a potential tool for preserving ailing coral reefs.

In the study, some corals were kept in water at a constant temperature of 82 degrees while others saw water temperatures fluctuating between 82 degrees and 88 degrees.  After 90 days of this treatment, the corals exposed to variable temperatures were able to tolerate high heat for longer periods before bleaching.  This training regime is akin to an athlete preparing for a race.

The findings suggest a possible approach for restoring coral reefs.  Nursery-raised corals that are “trained” to tolerate heat could be planted onto reefs endangered by warming waters.  Reefs populated by corals with boosted stamina to heat stress could have a greater chance of surviving the warming waters of the oceans.

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Some Corals Can Be Conditioned to Tolerate Heat, Study Finds

Photo, posted December 16, 2015, courtesy of Big Cypress National Preserve via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Coral Reef Status Report | Earth Wise

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In October, the Global Coral Reef Monitoring Network released the first-ever report collecting global statistics on the world’s corals.  It documents the status of reefs across 12,000 sites in 73 countries over 40 years.  Overall, the news is not good, but there were some bright spots.

From 2009 to 2018, the world has lost 14% of its corals, corresponding to about 4,500 square miles of coral.  Global warming has led to prolonged marine heatwaves that trigger coral bleaching.  Local pollution has also damaged reefs.   The International Panel on Climate Change has reported that 2 degrees Celsius of global warming would wipe out 99% of the world’s corals.

The report does show that corals can recover globally if given a decade of cooler waters.  Some places in the world – particularly the Coral Triangle in Asia, which contains nearly a third of the world’s coral – have actually seen coral growth over the past decade. 

The Global Coral Reef Monitoring network started collecting data in 1978.  Coral health was fairly steady until 1998 when the first mass bleaching event occurred, triggered by a powerful El Niño event.  For the next 12 years, corals recovered nicely, but then bleaching events in 2010 and 2015-17 took their toll.

The Pacific, Australia, and the Caribbean have all seen major decreases in coral.  The Coral Triangle is a major exception which is thought to be a result of genetic diversity among the region’s corals.

Coral conservationists globally are working to protect corals and to actively restore them.  The situation is fairly dire, but there continue to be reasons for hope.

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Finding Bright Spots in the Global Coral Reef Catastrophe

Photo, posted October 13, 2015, courtesy of Albert Straub via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Marine Heatwaves And Fish | Earth Wise

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Marine heatwaves are periods of abnormally high temperatures in the ocean that can trigger devastating impacts on ecosystems, including coral bleaching, toxic algal blooms, and mass mortality events.  Marine heatwaves can occur in any ocean and in any season.  They are defined based on the differences between actual and expected temperatures for the location and time of year.     

According to several studies, even under moderate climate warming scenarios, oceans will experience more frequent and longer-lasting marine heatwaves in the years to come.

Researchers from the University of British Columbia’s Institute for the Oceans and Fisheries in Canada have found that extremely hot years will wipe out hundreds of thousands of tons of fish globally this century.  These losses are in addition to the projected decreases to fish stocks from long-term climate change. 

Under a worst-case scenario where no action is taken to curb greenhouse gas emissions, the research team’s model predicts a 6% drop in the amount of potential catches per year.  In addition, the biomass (or amount of fish by weight) is projected to decrease in 77% of exploited species due to the extreme temperatures.

As a result of climate change and these extreme heat events, the research team projected that fisheries’ revenues would decrease by an average of 3% globally, and employment would fall by 2% globally – a loss of likely millions of jobs.

The research team says active fisheries management is critical.  Catch quotas, for example, need to be adjusted in years when fish stocks are suffering from marine heat events.  In severe cases, the fisheries may need to be shuttered in order to allow fish stocks to rebuild.  

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Fevers are plaguing the oceans — and climate change is making them worse

Marine heatwaves could wipe out an extra six per cent of a country’s fish catches, costing millions their jobs

Photo, posted October 11, 2016, courtesy of Kahunapule Michael Johnson via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Sunscreen For Corals | Earth Wise

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Sunscreen from beachgoers entering ocean waters is one of the greatest threats to coral reefs and there are global efforts to reduce or eliminate the use of many of the most harmful chemicals people use to protect themselves from the sun’s rays.  However, scientists at the Smithsonian Conservation Biology Institute have found that some corals have a natural sunscreen of their own that helps protect them from the effects of climate change.

Hawaiian blue rice corals feature a deep blue pigment that is created by chromoprotein that filters out harmful ultraviolet radiation from the sun.  UV damage has harmful impacts to reproduction in many coral species, but it appears not to have the same effect on blue rice coral.

In a study published in Scientific Reports, Smithsonian researchers studied the devastating effects that bleaching had on brown rice coral in the Hawaiian bleaching events of 2014 and 2015.  During the same events, blue rice coral either recovered quickly or was not affected by the elevated ocean temperature at all.

The blue-pigmented corals had dramatically greater reproductive vigor than the brown-pigmented version.  The key factor appears to be the sun-screening ability of the blue pigment in the particular symbiotic algae that lives inside the coral tissue known as zooxanthellae.  The coral protects the algae and in turn the algae provide the coral with food in the form of sugars produced as a waste product from photosynthesis.  In the case of the blue version, the algae also produce sunscreen for the coral.

By better understanding the role UV-protective pigments play in mitigating the adverse effects of climate change and warming oceans, scientists can learn why some species are better equipped to survive in a changing environment.

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Smithsonian Conservation Biology Institute Scientists Find Corals’ Natural “Sunscreen” May Help Them Weather Climate Change

Photo, posted September 28, 2009, courtesy of Matt Kieffer via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Helping Out Corals With Cool Water | Earth Wise

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Coral bleaching is happening five times more frequently than it did forty years ago.  Its increasing occurrence is a result of global warming which leads to marine heat waves – periods of higher ocean water temperatures.  Heat stress on living coral animals causes them to expel the algae that live symbiotically within the coral structure.  As the algae is expelled, the coral fades in color looking like it is bleached.  Without its algae partner, the coral eventually dies.

Given the increasing occurrence of marine heat waves, scientists are seeking novel ways to decrease heat stress in corals.  A new study by the Bermuda Institute of Ocean Science is investigating the use of artificial upwelling – the application of cooler, deep water – as a way to mitigate thermal stress on corals.

Upwelling is a natural process in the ocean in which winds push surface water away from a region – for example, a coastline – which then allows the uplift of deeper, colder waters to the surface.  Because such deeper waters are typically rich in nutrients, upwelling is important for supporting many of the world’s important commercial fisheries.  For this reason, artificial upwelling has sometimes been used to increase fish stocks in certain locations.

The new work placed coral colonies in aquaria in Bermuda and tested the effects of varying amounts and temperatures of deep cold-water pulses upon corals subjected to thermal stress.  The results showed that even short intrusions of cooler deep water (less than two hours per day) can mitigate thermal stress in corals.  The next steps are to find suitable parameters for artificial upwelling that maximize the benefits while minimizing potential harmful side effects on the corals and the ecosystems they support.

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Can pumping up cold water from deep within the ocean halt coral bleaching?

Photo, posted February 24, 2008, courtesy of Roderick Eime via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Heat-Resistant Coral | Earth Wise

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Coral reefs are in decline all over the world.  Corals are under increasing pressure as water temperatures rise and the frequency and severity of coral bleaching events increase.  Nowhere is this more evident than in Australia’s Great Barrier Reef system, where severe bleaching events have happened in three of the past five years. Long-term prospects for the survival of the world’s largest reef system are now considered to be poor.

A team of scientists at Australia’s national science agency – the Commonwealth Scientific and Industrial Research Organization – along with the Australian Institute of Marine Science and the University of Melbourne have successfully produced in a laboratory setting a coral that is more resistant to increased seawater temperatures.

The team made the coral more tolerant to temperature-induced bleaching by bolstering the heat tolerance of the microalgae symbionts that live inside the coral tissue.  They isolated the microalgae from coral and cultured it in the laboratory using a technique called “directed evolution”.  Over the course of four years, they exposed the microalgae to increasingly warmer temperatures.  When the heat-adapted strain of algae was reintroduced into coral larvae, the newly established coral-algal symbiosis was more heat tolerant than the original one.  The heat-tolerant microalgae are better at photosynthesis and improve the heat response of the coral animal.

The next step is to further test the algal strains in adult colonies across a range of coral species.  This groundbreaking research provides a promising and novel tool to increase the heat tolerance of corals and might potentially lead to a way to save the Great Barrier Reef as the world continues to warm.

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Scientists successfully develop heat resistant coral to fight bleaching

Photo, posted September 22, 2010, courtesy of NOAA via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Devastating Threat To Coral Reef Habitats | Earth Wise

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According to new research from scientists at the University of Hawaii Manoa, the warming and acidifying oceans could wipe out nearly all existing coral reef habitats by 2100.  In fact, the researchers predict that 70-90% of coral reefs will disappear over the next 20 years alone as a consequence of climate change and pollution. 

Some organizations are attempting to save coral habitats by transplanting live corals from labs to reefs.  The idea is that the new young corals will help revive the reefs.  But after mapping where such restoration efforts would be most successful, the research indicates that there will be little to no suitable habitat remaining for corals by 2100.  Small portions of Baja California and the Red Sea are two of the sites that could remain viable by 2100, although neither are ideal due to their proximity to rivers.  Sea surfaces temperature and acidity are two of the most important factors in determining the viability of a site for restoration.  

Warming ocean waters stress corals, which cause them to expel the symbiotic algae living inside them.  This turns the often colorful corals white – an event known as coral bleaching.  Bleached corals are not dead corals, but they are at a higher risk of dying.  These coral bleaching events are becoming more frequent as a result of the changing climate. 

The projected increases in human pollution will only play a minor role in the future elimination of coral reef habitats.  Ironically, that’s because humans have already caused such extensive damage to coral reefs that there aren’t many locations left to impact.

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Warming, acidic oceans may nearly eliminate coral reef habitats by 2100

Photo, posted September 28, 2009, courtesy of Matt Kieffer via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Pesticides In The Great Barrier Reef

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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.

Saved By The Trees

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The island of Kokota, part of the Zanzibar Archipelago off the coast of Tanzania, is tiny – only one square kilometer and home to just 500 people.  For centuries, its residents subsisted by harvesting the islet’s natural resources, including its trees.

By the early 21st century, the deforestation had become unsustainable and the islanders faced a crisis.  Fisheries were depleted, and rivers ran dry.  The changing climate brought rising sea levels, more erratic rainfall, and coral bleaching in the surrounding waters.  The situation looked hopeless.

But in recent years, the island has come back from the brink of ruin.  Reforestation efforts began in 2008 on the larger island of Pemba and on Kokota itself, led by a Pemba local and a Canadian tree planter who formed the non-profit Community Forests International.  Since then, nearly 2 million trees have been planted on the two islands.  Enthusiastic volunteers on Kokota usually help plant trees during the rainy season, when water is plentiful.

Community Forests International, along with spearheading the tree planting effort, also built Kokota’s first school, and installed rainwater storage tanks for the community.

The conservation group is now devising ways for Kokota to make more money by diversifying its agriculture with crops that grow well in its climate including spices like cloves, cinnamon, and nutmeg.  They are also helping locals to grow more and different vegetables in their gardens.

Small, poor communities are often the most vulnerable to the effects of climate change, such as drought, powerful storms, and depleted fisheries.  Tiny Kokota provides an example of an environmental comeback.  Fighting climate change requires economic solutions along with environmental solutions.  For this one tiny island, it  appears to have been saved by the trees.

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This island was on the brink of disaster. Then, they planted thousands of trees.

Photo, posted July 18, 2015, courtesy of Marco Zanferrari via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Heat-Resistant Corals

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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.

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A Small Win For Coral

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The Belize Barrier Reef is the largest barrier reef system in the Northern Hemisphere.  It extends roughly 200 miles, and is made up of a series of coral reefs, cays and islands, many of which are covered with mangroves. It was designated a Unesco World Heritage Site in 1996, and added to its endangered list in 2009.  

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A Philippine Coral Reef Survives

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One of the greatest coral reef ecosystems in the world, the Tubbataha Reef in the Philippines, continues to prosper.  Undersea coral walls that plunge more than 300 feet deep are home to some 600 species of fish and 360 kinds of coral, about half of all known species.  According to experts, the ocean wilderness of Tubbataha Reef is about the closest thing to a true natural state for any reef in the world.

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Some Good News For Coral Reefs

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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.

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