coral reefs

A New Deep-Sea Reef In The Galapagos | Earth Wise

June 2, 2023 By EarthWise Leave a Comment

Like in many other places around the world, ocean warming has mostly destroyed the shallow-water reefs in the Galapagos Islands. The islands are some of the most carefully protected places in the world, but they can’t escape the effects of a warming planet.

Recently, however, scientists have discovered a healthy, sprawling coral reef hidden deep under the sea in the Galapagos. More than 1,300 feet underwater, the reef extends for several miles along the ridge of a previously unknown volcano in the Galapagos Marine Preserve.

The reef is pristine and is teeming with all sorts of marine life including pink octopus, batfish, squat lobsters, and a variety of deep-sea fish, sharks, and rays.

The expedition that discovered the new reef was led by the University of Essex in the UK. Prior to this discovery, scientists thought that coral reefs were all but gone from the Galapagos. A period of ocean warming in 1982 through 1983 wiped out more than 95% of the corals in the archipelago. Only a few reefs in shallow waters remained. The newly discovered reefs are sheltered deep under the sea and would have been protected from the deadly heat.

According to the scientists from the expedition, the newly discovered reef potentially has global significance because it represents a site that can be monitored over time to see how such a pristine habitat evolves with the ongoing climate crisis. Reefs like this are clearly very old because coral reefs take a long time to grow. Finding this one means that it is likely that there are more healthy reefs across different depths that are waiting to be discovered.

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Pristine Deep-Sea Reef Discovered in the Galápagos

Photo, posted March 28, 2009, courtesy of Derek Keats via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Reef Insurance | Earth Wise

January 4, 2023 By EarthWise Leave a Comment

Coral reefs around the world face multiple dangers from warming waters, acidification, human activity, and more. Powerful storms often cause tremendous damage to reefs. When possible, snorkelers and divers are deployed to try to repair damage to reefs. But philanthropy and government grants are basically the only resources available to fund such actions.

Three years ago, tourist businesses and the government in the Mexican state of Quintana Roo purchased an insurance policy to offset costs of protecting the local parts of the Mesoamerican Reef. The environmental group the MAR Fund later took out an insurance policy on the rest of the reef in Mexico, Belize, Guatemala, and Honduras.

With this precedent, the Nature Conservancy recently purchased an insurance policy on behalf of the state of Hawaii to help offset repair work on its coral reefs. It is the first U.S. coral insurance contract.

Coral reefs are more than just hosts for marine life. They provide barriers against ocean storm surges, which is a major financial incentive for protecting them and hence an incentive to invest in insurance.

The new Hawaiian insurance policy has a premium of $110,000 a year and will provide $2 million in protection. Payouts occur when wind speeds go above 50 knots. No further proof of damage is required.

The Nature Conservancy has created teams called ‘Reef Brigades’ composed of snorkelers and divers who recover reef fragments, store them in ocean or shore-based nurseries, and then re-attach them when conditions are safe. It can be very expensive to do this sort of work, particularly when new corals grown in a nursery are required.

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Analysis: First U.S. coral insurance marks the rise of the reef brigades

Photo, posted September 14, 2011, courtesy of Greg McFall/NOAA Office of National Marine Sanctuaries via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Climate Resilient Microalgae | Earth Wise

July 21, 2022 By EarthWise Leave a Comment

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

April 19, 2022 By EarthWise Leave a Comment

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

December 23, 2021 By EarthWise Leave a Comment

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.

Coral Reefs And Ecosystem Services

October 18, 2021 By EarthWise Leave a Comment

A new study led by the University of British Columbia provides the first comprehensive look at what climate change, overfishing, and habitat destruction of coral reefs mean for their ecosystem services. For humans, this means how the global decline in coral reefs has affected their ability to provide essential benefits including food, livelihoods, and protection from storms.

The study found that global coverage of living corals has declined by about half since the 1950s and the diversity of reef species has declined by more than 60%. So, it is no surprise that there has been a significant loss in the ability of reefs to provide ecosystem services.

The study analyzed data from coral reef surveys around the world, fisheries catches, indigenous consumption, and more. Apart from the declines in reef coverage and biodiversity, the study found that fish catches on coral reefs peaked in 2002 and has steadily declined since then, despite increased fishing efforts.

The findings of the study led the researchers to conclude that continued degradation of coral reefs in the years to come threaten the well-being and sustainable development of millions of people in communities on the coast that depend on coral reefs. Fish and fisheries provide essential nutrients in places with few alternative sources of nutrition. Coral reef biodiversity and fisheries have added importance for indigenous communities, where important cultural relationships exist with reefs.

The study’s authors say that the results are a call to action. The level of destruction happening all over the world’s coral reefs is threatening people’s culture, their daily food, and their history. It is not just an environmental issue; it is a human rights issue.

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Photo, posted September 22, 2010, courtesy of David Burdick / NOAA Photo Library via Flickr.

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Coral Reefs And Fish Survival | Earth Wise

August 25, 2021 By EarthWise Leave a Comment

The precarious state of the world’s coral reefs has been a highly visible subject for a decade or more. Mostly what we hear about is the loss of some of the most beautiful sights on the planet. But there is far more at stake than scenic wonders.

The warming and acidifying of ocean waters are causing corals to increasingly bleach and often die. Corals provide a unique food source for some species of fish and a three-dimensional habitat for many others. The fish that depend on corals are often prey for fish that don’t depend directly on corals and so on up the food chain.

What happens to fish when coral reefs disappear? The fish species that feed on corals will starve while others will seek alternative rocky habitats.

A new study by the University of Helsinki uses statistical methods to predict how fish diversity will respond to declines in coral diversity. It concludes that a future coral loss might cause a 40% reduction in reef fish diversity globally. This is more than a loss of colorful sights for snorkelers; reef fishes provide essential protein for millions of people around the world.

The estimate of potential loss of fish species greatly exceeds the number of species known to depend directly or even indirectly on coral. The implication is that coral reef food webs will begin to unravel if corals go extinct. This unraveling is expected to be worse in some places than others. The Central Pacific, for example, could lose 60% of its reef fish.

For both snorkelers and for the millions who depend upon reef fishes for food, the need for greater efforts to conserve and restore coral reefs is apparent.

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A future ocean that is too warm for corals might have half as many fish species

Photo, posted September 27, 2009, courtesy of Matt Kieffer via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Offsetting Reef Acidification | Earth Wise

August 13, 2021 By EarthWise Leave a Comment

The Great Barrier Reef is the world’s largest coral reef system. It is composed of nearly 3,000 individual reefs and 900 islands covering an area of more than 130,000 square miles. In recent times, it has been under unprecedented stress from ocean warming, tropical cyclones, sediment and nutrient runoff, marine pests, and ocean acidification.

Among these stressors, ocean acidification is one of the most significant threats to the long-term viability of the reef because acidification affects the ability of corals to rebuild and repair their structures and recover from bleaching events.

New research from CSIRO, Australia’s national science agency, studied the impact of artificial ocean alkalinization on the acidity of the waters in the Great Barrier Reef. The idea is to inject a source of alkalinity into the ocean, an accelerated version of a natural process that occurs from the chemical weathering of minerals under the sea.

The results of the study, published in the journal Environmental Research Letters, are that injecting an alkalinizing agent into the ocean along the length of the Reef would make it possible to offset ten years’ worth of ocean acidification based on the present rate of human-generated carbon emissions. Such an effort could use an abundant mineral resource like olivine, which is already mined near the Great Barrier Reef. Releasing 30,000 tons a day of the alkalinizing agent from an existing shipping line from a bulk carrier would reach almost the whole of the Great Barrier Reef.

In response to the declining health of coral reef ecosystems, many different intervention concepts and technologies are under consideration. The goal of these would be to minimize environmental pressures and enhance the resilience of the ecosystems.

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Projected acidification of the Great Barrier Reef could be offset by ten years

Photo, posted August 4, 2019, courtesy of Larry Koester via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Sunscreen For Corals | Earth Wise

August 6, 2021 By EarthWise Leave a Comment

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.

Sunscreen And Coral Reefs | Earth Wise

May 18, 2021 By EarthWise Leave a Comment

The dangers of overexposure to UV solar radiation have led to the extensive production and use of sunscreen products. It is generally understood that many of the chemical compounds used in sunscreen products have toxic effects on marine organisms, but research in this area is relatively limited.

There are estimates that as many as 82,000 kinds of chemicals from personal care products have made their way into the world’s oceans. In 2015, it was estimated that around 14,000 tons of sunscreen are ending up in the world’s coral reefs per year and causing irreparable damage.

Eighty-five percent of the Caribbean’s coral reefs died before the turn of the century, not as a result of global warming, but because of pollution. Oxybenzone and octinoxate are two of the common sunscreen ingredients that are most toxic to corals. Preservatives like parabens are also toxic.

There are much safer sunscreens such as those based on zinc oxide or titanium oxide. In some places, such eco-friendly sunscreens are mandatory. Sunscreens with SPF values above 30 contain a higher percentage of chemicals and have been shown to not really provide any more protection than SPF 30 products.

Apart from the choice of sunscreen product, if one really wants to reduce the negative impact sunscreen has on reefs and marine life, wearing sun-protective clothing such as rash-guards will allow the use of much less sunscreen and therefore result in less of it entering the ocean.

Products that can help protect against the harmful effects of UV radiation on human health are extremely important, but it is also important to identify and quantify the risks associated with these products to reef ecosystems.

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How to Know If Your Sunscreen Is Killing Coral Reefs — and the Brands to Try Instead

Impacts of sunscreen on coral reefs needs urgent attention, say scientists

Photo, posted January 11, 2015, courtesy of Elch Korallen via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Restoring Coastal Ecosystems | Earth Wise

February 1, 2021 By EarthWise Leave a Comment

Research published by CSIRO, Australia’s national science agency, examined the positive effects of restoration efforts for coastal ecosystems in terms of biodiversity, local economies, and human wellbeing.

Coastal ecosystems include saltmarshes, mangroves, seagrasses, oyster reefs, kelp beds, and coral reefs. All of these have suffered declines of up to 85% over recent decades. The research identified a number of successful coastal and marine restoration projects in recent years that indicate the likelihood that such efforts could be expanded by as much as a factor of ten to support human health and wellbeing, boost the adaptation response to climate change, and generate jobs.

Some of the successful efforts identified included projects in the Great Barrier Reef to harvest coral larvae to boost large-scale coral restoration efforts. Simple changes to how saltmarshes are planted have resulted in doubled survivorship and biomass. In the U.S., the propagation of seagrass seeds has resulted in seagrass meadows recovering in areas where they had been lost decades ago. In Indonesia, recovery of reefs impacted by blast fishing has been achieved by placing rocks or other hard structures underwater to help with coral colonization.

Investing in coral restoration creates jobs and can be used as a strategy to boost economic recovery and coastal marine health. Restoration of marine habitats like kelp forests and oyster reefs has improved commercial and recreational fishing.

The United Nations has recognized the importance of coastal restoration and has declared the Decade on Ecosystem Restoration to start from 2021.

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Scientists shine light on ‘bright spots’ to restore coastal ecosystems

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

Earth Wise is a production of WAMC Northeast Public Radio.

Sharks On The Decline | Earth Wise

September 4, 2020 By EarthWise Leave a Comment

During the past 70 years, global shark populations have been on the decline. Many species have become threatened or endangered. Conservation efforts have been underway in many places, but shark populations continue to be at risk because of over-fishing and habitat loss.

A comprehensive study by marine biologists at Texas A&M University deployed more than 15,000 baited remote underwater video stations on 371 coral reefs in 58 countries. The study included 59 different shark species in the Atlantic, Pacific and Indian Oceans. The researchers were surprised to find that no sharks at all were detected in almost 20% of the locations surveyed and were almost completely absent from coral reefs in several nations.

Scientists believe that demand for shark products, such as fins and meat, and bycatch (that is, sharks captured in nets by fisherman trapping other kinds of fish) are strong contributors to the widespread declines in shark numbers around the world.

The study shows that if corrective steps are not taken in regions where marine management is still ineffective, continued depletion of shark populations is highly likely.

Sharks have important roles in marine ecosystems. When their habitats deteriorate and their populations decrease, ecosystem stability and health is degraded because sharks help regulate prey populations.

Some countries, notably the Bahamas, are combating the problem by providing sanctuaries for sharks where fishing and harvesting is prohibited. Such places support some of the healthiest shark populations in the world. However, the decline of coral reefs is just another challenge facing shark populations around the world.

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Study Shows Alarming Decline In Shark Numbers Around The World

Photo, posted January 9, 2017, courtesy of Kris-Mikael Krister via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Heat-Resistant Coral | Earth Wise

June 23, 2020 By EarthWise Leave a Comment

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 Giant Marine Preserve | Earth Wise

May 4, 2020 By EarthWise Leave a Comment

The Seychelles islands are located east of Kenya, near the equator. Its beautiful beaches, virgin jungles, thriving coral reefs, and UNESCO-listed nature reserves are among the many attractions of the archipelago’s 115 islands. The larger inner islands are quite developed for tourists, studded with many luxurious five-star resorts. The natural wonders of the Seychelles are clearly its prime asset.

Given this, the Seychelles have now established 154,000 square miles of marine protected areas, fulfilling a pledge to protect nearly a third of its vast territorial waters. This is an area twice the size of Great Britain.

About half of the newly protected areas will be “no-take zones” in which economic activity such as fishing and mining will be prohibited. Only limited economic activities will be permitted in the other half of the protected areas.

The President of the Seychelles signed the decree establishing the marine reserve in mid-March. The reserve will help protect the nation’s fisheries resources and safeguard a host of species including endangered sea turtles, sharks, and the Indian Ocean’s last remaining population of dugongs, which are marine mammals similar to manatees.

The funding for managing and protecting the new marine reserves will come from what is termed a debt-for-nature deal. It is an agreement that was worked out with the help of The Nature Conservancy that allows the country to restructure nearly $22 million in foreign debt in exchange for protecting marine resources and enacting climate adaptation measures.

This major expansion of the Seychelles’ marine protected area is a major step in the conservation of the archipelago’s biodiversity. The success of that conservation will ultimately depend upon enforcement, public-private partnerships, and innovative management.

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Seychelles Creates a Marine Reserve Twice the Size of Great Britain

Photo, posted October 22, 2017, courtesy of Falco Ermet via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Climate Change And Dolphins

May 27, 2019 By EarthWise Leave a Comment

We don’t think of heatwaves as something that affects the ocean, but increasingly, as the planet warms, there have been instances where ocean water temperatures become much higher than normal for extended periods of time. There has been much discussion of this phenomenon with regard to coral reefs where the catastrophic rise in coral bleaching events has been the result.

Recently, a study at the University of Zurich looked at the effects of ocean heatwaves on marine life higher in the food chain. They studied the well-known dolphin population in Shark Bay, Western Australia.

In early 2011, a heatwave caused water temperatures in Shark Bay to rise more than 4 degrees above the annual average for an extended period. This led to a substantial loss of seagrass, which is a driving factor in the Shark Bay ecosystem.

The researchers investigated how this environmental damage affected survival and reproduction of dolphins, using long-term data on hundreds of animals collected over a ten-year period from 2007 to 2017.

Their analysis showed that dolphins’ survival rate dropped by 12% and female dolphins were giving birth to fewer calves. That phenomenon that began in 2011 lasted at least until 2017.

The researchers were surprised by the extent and the duration of the influence of the heatwave, especially the fact that the reproductive rate of dolphins had not returned to normal even after 6 years.

This study shows for the first time that marine heatwaves not only affect organisms at the lower levels of the food chain, but also might have considerable long-term consequences for the animals at the top, such as dolphins.

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Climate change is a threat to dolphins’ survival

Photo, posted December 14, 2014, courtesy of Ed Dunens via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

How Much CO2 Can The Oceans Hold?

May 2, 2019 By EarthWise Leave a Comment

The carbon dioxide that enters the atmosphere doesn’t necessarily stay there. As part of the natural carbon cycle, much of it goes into plants, soil and, very significantly, the ocean. In fact, the world’s oceans are a sink for human-generated carbon dioxide without which the extent of global climate change would be far worse.

Oceans takes up CO2 in two steps: first the CO2 dissolves in the surface water. Then, the ocean’s overturning circulation distributes it. Currents and mixing processes transport the dissolved CO2 from the surface deep into the ocean’s interior, where it accumulates over time.

A long-standing priority for climate researchers is to determine how much of the CO2 we produce is being absorbed by the oceans and, ultimately, how much can they hold?

An international team of scientists has recently provided some answers. As reported in Science, the researchers have determined that the oceans have taken up from the atmosphere as much as 37 billion tons of human-made carbon between 1994 and 2007. This figure corresponds to nearly a third of all the anthropogenic CO2 emitted during that time.

Furthermore, they found that the percentage of CO2 taken up by the oceans has remained relatively stable compared to the preceding 200 years even as the absolute quantity has increased. So, evidently, the oceans’ capacity for carbon dioxide has not yet been saturated.

That’s the good news. The bad news is that putting all that CO2 into the oceans has a steep price: the dissolved CO2 acidifies the water. The consequences for a wide range of marine life including coral reefs are serious and getting worse. We need to drastically reduce carbon emissions.

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Ocean sink for human-made carbon dioxide measured

Photo, posted November 5, 2018, courtesy of 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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