Earth Wise

A look at our changing environment.

You are here: Home / Archives for coral reefs

coral reefs

Sea turtles and climate change

By Leave a Comment

Life is a struggle for survival from the moment a sea turtle hatches.  In fact, only one sea turtle out of every 1,000 typically reaches adulthood as a result of natural predators and other challenges.  Those fortunate enough to make it to adulthood face serious threats from humans. For example, sea turtles are hunted for their meat, eggs, and shells in some regions. Their beach habitats get developed. Harmful marine debris and oil spills pollute their waters and beaches.

Now, climate change is exposing sea turtles to even greater threats.  Rising sea levels and stronger storms threaten to erode and destroy their nesting beaches. Warming oceans disrupt currents, potentially exposing sea turtles to new predators, and damaging the coral reefs that some depend on to survive.

As these environmental challenges intensify, sea turtles are beginning to adapt in surprising ways.  According to a new study by researchers from the University of Exeter in England and the Society for the Protection of Turtles in Cyprus, sea turtles are responding to climate change by nesting earlier.  Researchers monitoring nesting green and loggerhead turtles in Cyprus have discovered they are returning to their regular nesting spots earlier each year to compensate for rising temperatures.

Temperature plays a crucial role in determining the biological sex of sea turtles.  Warmer nest temperatures produce more female hatchlings than males.

But at least for now, sea turtles seem to be doing enough to ensure their eggs continue to hatch by nesting earlier in more ideal temperatures.  While this is good news, there’s no guarantee that it will continue. 

**********

Web Links

Turtles change nesting patterns in response to climate change

Photo, posted December 20, 2021, courtesy of Cape Hatteras National Seashore via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Corals and climate change

By Leave a Comment

Climate change is a major threat to coral reefs around the world.  Ocean warming triggers coral bleaching – a stress response where corals expel the symbiotic algae essential for their survival.  If coral bleaching is severe, it can lead to coral death.

A new study led by scientists from Newcastle University in England suggests that corals are unlikely to adapt to ocean warming quickly enough to keep pace with global warming, unless there are rapid reductions in global greenhouse gas emissions.

The study, which was recently published in the journal Science, found that coral heat tolerance adaptation via natural selection could keep pace with ocean warming, but only if the climate goals of the Paris Agreement are realized.  In the Paris Agreement, countries agreed to limit global warming by the end of the century to two degrees Celsius above pre-industrial levels.  

However, current climate policies around the world have the globe on track to warm by three degrees Celsius.  According to the research team, this could lead to significant reductions in reef health, elevated risks of local coral extinctions, and considerable uncertainty in the so-called “evolvability” of corals. 

Coral reefs are among the most biologically diverse ecosystems on Earth.  They are often referred to as the “rainforests of the sea” because they support an incredible variety of marine life.  They provide essential ecosystem services, such as protecting coastlines from erosion and storm surges, supporting fisheries, and serving as a source of income through tourism. Coral reef health is vital for the health of the planet.

**********

Web Links

Coral adaptation unlikely to keep pace with global warming

Photo, posted June 9, 2012, courtesy of Bokissa Private Island Resort via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Tourism and climate action

By Leave a Comment

Australia’s Great Barrier Reef is one of the foremost natural wonders of the world and is a major tourist attraction.  It is well-known that the changing climate is threatening the survival of the Great Barrier Reef as well as other coral reefs around the world.  A recent study by researchers at the University of Queensland looked at the reactions of tourists to being informed about the impact of the changing climate on the reef.

The Great Barrier Reef faces many challenges.  Unprecedented marine heatwaves have triggered repeated mass coral bleaching events over the past decade. These climate driven disturbances are compounding the cumulative effects of chronic problems such as unsustainable fishing, pollution, and sedimentation as well as acute disturbances such as tropical cyclones and outbreaks of crown-of-thorns starfish.

Operators of five reef tourism boats assisted in the study.  As part of their boat trips, tourists were given climate information via a marine biology presentation and there were also posters around the vessel as well as regular mentions of climate change impacts and actions throughout the trip.

The tourism industry often has the idea that providing information on climate change might be detrimental to people’s enjoyment – basically a buzzkill.  But based on surveys conducted at the end of the trips, the researchers found that informing tourists about climate impact didn’t negatively affect their experience.  In fact, most tourists actually wanted more information, particularly about how they can take meaningful actions of their own.

The researchers believe that their study provides further opportunity to improve climate communication and effectively promote climate change engagement among tourists.

**********

Web Links

Reef tourism encourages climate action

Photo, posted October 7, 2008, courtesy of eGuide Travel via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Natural solutions for coastal defense

By Leave a Comment

Protecting coastal cities and towns from the dangers of tsunamis, storm surges, and sea-level rise has become an ever-increasing challenge.  There are so-called hard coastal defenses as well as nature-based solutions.  A new study by the University of Tokyo has found that combining the two types of defenses may be the most effective way to protect, support, and enrich coastal communities.

Sea walls, dikes, dams, and breakwaters are the traditional hard measures.  They are popular and have proven track records but are facing challenges to keep pace with increasing climate risks.  They are expensive to build and require continuous upgrades and repairs.  While they do provide protection from many disaster risks, they also can cause significant disruption to coastal ecosystems as well as to coastal communities.

Nature-based coastal defenses include such things as mangroves and coral reefs.  So-called soft measures involve restoring, rehabilitating, reforesting, and nourishing natural ecosystems that protect coastal areas.

The Tokyo researchers analyzed the defense strategies in terms of risk reduction, climate change mitigation, and cost-effectiveness over a 20-year period. The results of the study were that among all coastal defense options in lower-risk areas, hybrid measures provide the highest risk reduction and can harness the advantages of both hard and soft measures. 

The findings provide strong evidence for integrating nature-based components into coastal defenses, but these approaches have not yet been adequately tested in circumstances of extreme events and high-risk urgency.  Research in this area has important implications for policy makers, coastal planners, and communities looking to make evidence-based decisions.

**********

Web Links

A natural touch for coastal defense

Photo, posted October 22, 2021, courtesy of Kevin Dooley via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Global coral bleaching

By Leave a Comment

The world’s coral reefs are in the midst of a global bleaching event being driven by extraordinarily high ocean temperatures.  This is the fourth such global event on record and is predicted to be the largest one ever.  Coral bleaching occurs when corals are stressed by heat and eject the symbiotic algae within them that they need to survive.  Bleached corals can recover if water temperatures cool soon enough.  Otherwise, they die.

Each of the three previous coral bleaching events has been worse than the last.  The first, in 1998, affected 20% of the world’s reefs.  The second, in 2010, affected 35%.  The third, from 2014 to 2017, affected 56% of reefs.

The current bleaching event was confirmed by satellite observations early in April and was already seen to be affecting more than half of the world’s coral areas across the Pacific, Indian, and Atlantic Oceans.  The ongoing event is expected to be the worst bleaching ever experienced by Australia’s Great Barrier Reef.  A small saving grace is that the current bleaching event is not expected to be of extremely long duration because the El Niño in the Pacific has abated.

Coral bleaching events are becoming more severe and frequent due to increased marine heat waves driven by climate change.  Last year was particularly difficult for corals as global sea temperatures reached record high levels for several months.

Widespread coral bleaching impacts economies, livelihoods, food security, and more.  Coral reefs provide ecosystem services essential to marine life and human populations as well.  Global action will be needed for coral interventions and restorations.

**********

Web Links

Satellites watch as 4th global coral bleaching event unfolds

Photo, posted March 23, 2012, courtesy of Oregon State University via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Artificial reefs

By Leave a Comment

The coral reefs that surround tropical islands are a refuge for a wide variety of marine life and also form a natural buffer against stormy seas.  The changing climate is bleaching coral reefs and breaking them down.  Extreme weather events are becoming more common and are threatening coastal communities with flooding and erosion.

Researchers at MIT are designing architected reefs – sustainable offshore structures that mimic the wave-buffering effects of natural reefs and can also provide habitats for fish and other marine life.

There are already artificial reefs in a number of places used to protect coastlines.  These are typically made from sunken ships, retired oil and gas platforms, and even assemblies of concrete, metal, car tires, and stones.  Generally, it takes quite a lot of material to form an effective barrier to waves.

The MIT group has developed a cylindrical structure surrounded by four rudder-like slats.  Their experiments have shown that when this structure stands in the way of a wave, it efficiently breaks the wave and creates turbulent jets that dissipate the energy in the wave.  The engineers calculated that the new design could reduce as much wave energy as existing artificial reefs but use 10 times less material.

Based on the initial experiments with lab-scale prototypes, these artificial reefs would reduce the energy of incoming waves by more than 95%.

Coral reefs are only found in tropical waters, whereas these artificial reefs don’t depend on temperature and could be placed along any coastline for protection.  In a time of rising seas and increasingly frequent storms, these artificial reefs may be just what coastlines need.

**********

Web Links

Artificial reef designed by MIT engineers could protect marine life, reduce storm damage

Photo, posted December 9, 2010, courtesy of Phoenix Wolf-Ray via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Seabirds rescuing coral reefs

By Leave a Comment

A new study by researchers at Lancaster University in the UK has found that the presence of seabirds on islands adjacent to tropical coral reefs can more than double the coral growth rates on those reefs.

The study found that when coral reefs grow faster, they can bounce back more quickly from bleaching events that occur when the seas become too warm.  The focus of the study was a type of coral called Acropora, which provides complex structures supporting fish populations and reef growth. 

The researchers found that Acropora around islands populated by seabirds recovered from bleaching events about 10 months faster than reefs located away from seabird colonies.  Speeding up coral recovery times could prove the difference between continuing to bounce back from bleaching events and dying off.

The seabirds are helping the coral reefs with their droppings.  The birds feed on fish in the open ocean far from islands and then return to the islands to roost.  They deposit nitrogen- and phosphorus-rich nutrients in the form of guano, some of which is washed off of the islands by rain and into the surrounding seas.  The nutrients fertilize corals and other marine species.

To determine whether the faster growth rates were really due to the bird-supplied nutrients, the researchers studied rat-infested islands that had no bird populations.  The study confirmed that it was the presence of seabirds that provided enhanced nutrients for the coral reefs.  In fact, a primary outcome of the study was to add further weight to the growing body of evidence of the ecological damage across ecosystems on land and sea from invasive rats on tropical islands.

**********

Web Links

Feathered friends can become unlikely helpers for tropical coral reefs facing climate change threat

Photo, posted September 15, 2019, courtesy of Rickard Zerpe via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Deeper corals bleaching

By Leave a Comment

When ocean waters get too warm, corals – which are actually tiny animals – eject the colorful algae that inhabit their tissues.  The symbiotic relationship between coral polyps and algae is essential to coral survival   When the algae is ejected, previously colorful coral turns white, and the coral can ultimately die.  If waters cool off, the algae can reestablish themselves and the coral can regain its color and health.

The world’s oceans have been warming at an unprecedented rate, making coral bleaching and die-off a global phenomenon.  It is estimated that half of the planet’s reefs have already disappeared.  Some places are worse off than others.  For example, almost 95% of coral reefs in Southeast Asia are threatened.  Florida’s reefs are especially threatened, particularly since there have been unprecedented marine heatwaves off its coast.

It has long been assumed that deeper reefs, where water is cooler, would remain safe from the effects of warming, but a few years ago researchers recorded coral bleaching some 300 feet underwater along the Egmont Atoll in the western Indian Ocean.  At one point, bleaching affected 80% of corals in some areas.  This discovery came as a huge surprise to oceanographers.  It was probably associated with an El Niño-like phenomenon in the waters and those reefs have mostly recovered in the intervening years.

Fairly recently, researchers have found pristine coral reefs deep down in the waters off the Galapagos Islands, where shallow reefs have largely disappeared.  There are likely to be similar reefs in the ocean depths around the world, but scientists are expressing concern that even coral reefs lying deep beneath the ocean surface may not ultimately be protected from the warming seas.

**********

Web Links

As Oceans Warm, Coral Bleaching Seen at Greater Depths

Photo, posted June 5, 2023, courtesy of Ryan Hagerty / USFWS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Cryopreserving Corals | Earth Wise

By Leave a Comment

Recent climate models estimate that if the effects of climate change are not mitigated soon enough, 95% of the world’s corals could die by the mid 2030s.  Given the current rate of greenhouse gas emissions, this is an increasingly likely outcome.  Coral reefs are estimated to have a $10 trillion economic value apart from their essential role in marine ecosystems.

Researchers at the University of Hawaii at Manoa have demonstrated a successful technique for cryopreserving entire coral fragments; in other words, preserving coral using cold temperatures and successfully reviving them.

Existing coral cryopreservation techniques rely on freezing sperm and larvae, which can only be collected during spawning events, which occur only a few days each year for coral species.  This makes it logistically very challenging for researchers and conservationists.

The Hawaiian researchers focused on a process called isochoric vitrification, which is a method of freezing with liquid nitrogen that prevents the formation of ice crystals.  They tested the technique with thumbnail-sized fragments of coral, freezing them in small aluminum chambers which restrict the growth of ice crystals that would otherwise damage delicate polyp tissues.  Once the chambers were warmed, the fragments were transferred to seawater and allowed to recover.  They found that the revived corals behaved the same as those that were never cooled.

The process holds great promise to conserve the biodiversity and genetic diversity of coral.  If the process can be scaled up, it may be possible to preserve as many species of coral as possible by 2030, when it may no longer be viable for them to survive in the warming and acidifying oceans.

**********

Web Links

Cryopreservation breakthrough could save coral reefs

Photo, posted June 2, 2023, courtesy of USFWS – Pacific Region via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The Value Of Seagrass | Earth Wise

By Leave a Comment

Seagrasses are found in shallow salty and brackish waters in many places around the world, from the tropics to the Arctic Circle.  They get their name from their long green, grass-like leaves.  They are not seaweeds at all but are more closely related to flowering plants on land. 

We hear a lot about threatened ocean ecosystems and most of the attention is on coral reefs and coastal mangrove forests.  Seagrass meadows get much less press, but they in fact provide wide-ranging services to society and store a great deal of carbon.

A new study by the University of Michigan demonstrates that seagrass ecosystems should be high up on the global conservation agenda.  The study puts a dollar value on the many services – which include storm protection, fish habitat, and carbon storage – provided by seagrasses in the Caribbean.  The numbers are enormous.

The researchers estimate that the Caribbean holds up to half of the world’s seagrass meadows by surface area, and it contains about a third of the global carbon storage by seagrasses.  They calculated that the Caribbean seagrasses provide about $255 billion in services to society each year, which includes $88 billion in carbon storage.

In the Bahamas alone, ecosystems services provided by seagrasses are valued at more than 15 times the country’s 2020 gross domestic product.

Blue carbon is the name used to describe carbon stored in coastal and open-ocean ecosystems.  The idea of selling blue carbon offset credits, which monetize the carbon stored in this way, is gaining traction.  For many Caribbean nations, this is likely to provide impetus for protecting seagrass ecosystems from human impacts, including nutrient pollution and overfishing.

**********

Web Links

Caribbean seagrasses provide services worth $255B annually, including vast carbon storage, study shows

Photo, posted June 27, 2023, courtesy of Daniel Eidsmoe via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

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

By 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.

**********

Web Links

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

By 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.

**********

Web Links

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

By 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.

**********

Web Links

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

By 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.

**********

Web Links

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

By 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.

**********

Web Links

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

By 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.

**********

Web Links

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

XXXXXXXXXXX

Coral Reefs And Fish Survival | Earth Wise

By 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.

**********

Web Links

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

By 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.

**********

Web Links

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

By 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.

**********

Web Links

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

By 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.

**********

Web Links

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.

WAMC Northeast Public Radio

WAMC/Northeast Public Radio is a regional public radio network serving parts of seven northeastern states (more...)