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Corals Saving Corals | Earth Wise

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A new study by researchers at the University of California, Davis, has found that under the right circumstances, disease-resistant corals can rescue corals that are more vulnerable to disease.

The researchers monitored a disease outbreak at a coral nursery in the Cayman Islands.  They tracked the presence of disease in 650 coral fragments in various arrangements over a period of five months.  They found that some corals are more resistant to disease just by being around other corals that are particularly resistant.  In general, when there are only corals of the same genetic makeup, they are more vulnerable to disease than corals that grow among a mixture of genotypes.  But beyond that, some vulnerable corals become more resistant to disease just by being around other corals that are particularly resistant.  Proximity to the resistant genotypes helped to protect the susceptible corals from the effects of disease.

These findings provide new evidence that genetic diversity can help reduce disease transmission among corals and furthermore, it is important to consider how corals are arranged in coral nurseries or in reef restoration projects.

The ability of resistant coral to help protect vulnerable individuals appears to be similar to how vaccinations work among humans.  Vaccinated individuals resist a disease, which effectively erects a barrier that weakens a disease’s ability to move through a population.

The researchers hope that the findings of this study will be integrated into coral nursery and reef restoration projects.  By intentionally arranging corals with mixtures of genotypes, it will help rebuild coral resilience and help those corals that are vulnerable to disease to thrive.

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Corals Saving Corals

Photo, posted December 30, 2014, courtesy of NOAA’s National Ocean Service via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Making Cotton More Sustainable | Earth Wise

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In the United States, cotton is a $7 billion annual crop grown in 17 states.  Cotton plants in the largest producing countries in the world – India, China, and the U.S. – are genetically very similar and, like other crops that lack diversity, can be at risk.

Cultivated cotton around the world has been bred to look and act very similar.  It is high yielding and easy to harvest using machines.  But it is also wildly unprepared to fight disease, drought, or insect-borne pathogens.

Researchers are looking beyond breeding for ways to combat the low genetic diversity of cultivated cotton.  There are new approaches that combine breeding with elements of genetic modification.  Most cotton in the U.S. has already been genetically modified to resist caterpillar pests.  But as new problems emerge, new solutions will be needed that may require complicated changes to the cotton genome.  Getting regulatory approval for a genetically modified crop is a long and expensive process.

However, ordinary genetic modification is not the only possibility.  Modern genetic sequencing technology can allow researchers to examine various wild cotton varieties and identify the genetic markers for desirable traits.  Once valuable genes in wild species have been identified, traditional plant breeding techniques could be used to produce cultivated cotton varieties that are more resistant to disease and drought.

Climate change is raising average global temperatures and some important cotton-producing regions such as the U.S. Southwest are becoming drier.  Researchers are hoping to produce cultivated cotton that can tolerate drought at the seedling stage.  The ultimate goal is to create more sustainable and genetically diverse cotton that can thrive in a changing world.

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Cotton Breeders Are Using Genetic Insights To Make This Global Crop More Sustainable

Photo, posted November 9, 2008, courtesy of BP Takoma via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Healthy Soil Is Healthy For People | Earth Wise

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A new study by researchers at the University of Washington looked at the impact of regenerative farming practices on the nutritional content of the food that is grown. 

Regenerative agriculture involves farming practices that not only “do not harm” to the land but actually improve it by regenerating and revitalizing the soil.  The practices focus on topsoil regeneration, increasing biodiversity, improving the water cycle, and enhancing ecosystem services.  Examples are soil-building techniques that minimize plowing, the use of cover crops, and the planting of diverse crops rather than monocultures.

The study included 10 farms across the U.S. that followed soil-friendly practices for at least five years. The results were that the crops from those farms had a healthier nutritional profile than the same crops grown on neighboring, conventional farms.  In particular, there was a boost in certain minerals, vitamins and phytochemicals that are beneficial to human health.  Across the board, regenerative practices resulted in crops with more anti-inflammatory compounds and antioxidants.

The participating farms grew one acre of a test crop – peas, sorghum, corn, or soybeans – for comparison with the same crop grown on a neighboring farm using conventional agriculture.  Analysis showed that the farms practicing regenerative agriculture had healthier soils, as measured by their organic matter – or carbon – content and by other tests. 

Organic farms avoid chemical pesticides, but they operate with a variety of farming processes.  Nonetheless, they have also been found to produce crops with higher levels of beneficial nutrients.  The biology of the soil in which crops are grown is an important factor for human health.  It isn’t just what we eat that matters; it is how we grow it.

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Farms following soil-friendly practices grow healthier food, study suggests

Photo, posted January 10, 2020, courtesy of Les via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Fighting Disease in Cavendish Bananas | Earth Wise

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Cavendish bananas account for about half of global banana production and the vast majority of bananas entering international trade.  The plant is unable to reproduce sexually and instead is propagated via identical clones.  So, the genetic diversity of the Cavendish banana is exceedingly low. 

In 2008, Cavendish cultivars in Sumatra and Malaysia started to be attacked by Panama disease, a wilting disease caused by a fungus.  In 2019, Panama disease was discovered on banana farms in the coastal Caribbean region, its first occurrence in the Americas.  In the 1950s, Panama disease wiped out the Gros Michel banana, the commercial predecessor of the Cavendish.

Scientists at the University of Cambridge have found a novel way to combine two species of grass-like plants – which include bananas, rice, and wheat – using embryonic tissue from their seeds.  The technique allows beneficial characteristics, such as disease resistance, to be added to the plants.

Joining the shoot of one plant to the root of another to grow as one plant is known as grafting.  It was thought to be impossible to do with grass-like plants – called monocotyledonous  grasses – because they lack a certain tissue type in their stems.  But the new research, published in the journal Nature, showed it can be done with the plants in their earliest embryonic stages.

Cavendish bananas are sterile, so disease resistance can’t be bred into future generations.  But the grafting technique may provide a way to produce Cavendish banana plants that are resistant to Panama disease.  It may be possible to save an important food crop before it is too late.

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New grafting technique could combat the disease threatening Cavendish bananas

Photo, posted July 1, 2015, courtesy of Augustus Binu via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Crops Threatened With Extinction | Earth Wise

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Crop variety and diversity are critically important for global food security as well as for the livelihoods of millions of people.  This diversity entails both the different species of food crops as well as the so-called farmer varieties of crops that in many cases have been cultivated and safeguarded for millennia.

It is well-known that many of these crops and varieties have been rapidly disappearing, but data has been scarce on just how many have been lost, how many we are losing, and which ones are the most threatened going forward.

A new study utilizes a methodology known as the Varietal Threat Index, which was developed by the Alliance of Bioversity International and CIAT, the International Center for Tropical Agriculture.  The study assessed about 600 farmers from seven Indian states, covering five different agroecological areas.  The farmers were selected based on their knowledge of crops and varieties across the 17 study sites.

The farmers listed the crops and varieties grown in their households, noted their uses, and indicated their spread and abundance, including information on varieties grown during the previous ten years which were no longer grown.

The results of the study showed that while there is a significant diversity of landraces – which are local varieties of species developed over time – more than 50% are threatened.  The trend is that crops and varieties mostly used for consumption are most often under threat, whereas varieties with multiple uses are less likely to be threatened.

Studies of this type can aid the development of targets and indicators to monitor the global status of plant genetic resources for food and agriculture and help inform urgent priority conservation actions.

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More than half of surveyed crop varieties are under threat of extinction, according to study in India

Photo, posted February 21, 2014, courtesy of Atibordee Kongprepan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Coral Reefs And Ecosystem Services

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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

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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.

Transmission Lines And Wildlife Habitat Connectivity | Earth Wise

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Electrical transmission lines and their support towers tend to be a blight on the landscape but are something modern society cannot avoid.  Power transmission networks – with towers every 200 meters or so of line – are in place throughout the world’s developed nations.  Another common feature of developed nations is the fragmentation of animal species caused by human activity breaking up their natural habitats.

It is important for biodiversity conservation for animals to get their environments connected.   It turns out that transmission line infrastructure can provide an important tool for reconnecting wildlife habitats.

In a study conducted in Spain’s Andalusia region, scientists planted native shrubs and seedlings under six towers along power lines running through cereal cropland.  The area of each tower base was 100 square meters.

Compared to four control sites, the researchers measured increased population density and diversity among arthropods and small mammals observed in the four-year study. 

Enhancing connectivity through networks of habitat corridors or stepping-stone patches has become a key concept in conservation biology and landscape ecology.  Renting or buying large parcels of land to connect protected natural areas to one another would be cost prohibitive but planting suitable native shrubs and other flora under existing transmission line networks can provide many of the same benefits.

In general, power companies pay rent to landowners – often farmers or agribusinesses – for the rights to place towers on their land.  Because it is difficult to work the areas under towers with farm equipment, that space is typically unused, which opens the door to low-cost efforts by environmentalists.

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Electrical transmission lines have power to enhance habitat connectivity for wildlife

Photo, posted April 29, 2018, courtesy of Georgi Todorov/digitalnovas.com via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Living On Trash | Earth Wise

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Litter is persistent and widespread in rivers worldwide.  The world’s major rivers and estuaries are hotspots for plastic waste.  Trash and microparticles wash down tributaries and build up before rivers enter oceans.

New research published in the journal Freshwater Biology has found that as this waste accumulates, aquatic river species like insects and snails are increasingly choosing to settle on plastic rather than on natural features like rocks and fallen branches.

Researchers from the University of Nottingham in the UK collected plastic waste from three rivers in eastern Britain along with rocks from the same rivers.  Their analysis of all the macroinvertebrates on the items’ surfaces found that the surfaces of plastic waste items had nearly four times the diversity of the small animals as did the rocks.  In addition, the more complex the plastic’s surface was, the higher the diversity.

The growing abundance of plastic waste coincides with a decline in natural habitat features in urban rivers.  This is a result of increasing amounts of sedimentation from development that blankets riverbeds in silt and sand, restricting the supply and movement of rocks, fallen tree branches, and aquatic plants.

Clearly litter can serve as a place for various species to colonize, but trash is not a good environment for them.  Trash can release toxic chemicals and entangle animals.  Microplastics pose risks for the animals if ingested.

Estimates are that between 1.15 and 2.41 million tons of plastic waste enter the ocean every year from rivers around the world.  Natural habitats have become rare in urban rivers.  River ecosystems built around piles of trash are not a good thing.

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As Plastic Pollution in Rivers Gets Worse, Species Are Increasingly Living on Litter

Photo, posted August 17, 2010, courtesy of Renee_McGurk via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Why Have Crocodiles Changed So Little Over Time? | Earth Wise

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Crocodiles today look very similar to ones from the Jurassic period some 200 million years ago.  In fact, there are very few species of crocodilians alive today – approximately two dozen to be exact.  Many other species have achieved a diversity of many thousands of species in the same amount of time. 

During prehistoric times, many more types of crocodiles roamed the earth, including some as big as dinosaurs and other serpentine forms that lived in the sea.  

According to findings by scientists at the University of Bristol in the U.K., a stop-start pattern of evolution could explain why crocodiles have changed so little over time. In the study, which was recently published in the journal Nature Communications Biology, researchers describe how crocodiles follow a pattern of evolution known as “punctuated equilibrium.”  In other words, crocodiles’ rate of evolution is generally slow, but occasionally picks up because the environment has changed.     

According to the research team, this slow rate of evolution is how crocodile diversity became so limited.  It appears crocodiles arrived at a body that was efficient and versatile.  They didn’t need to continue to change in order to survive.

This efficiency and versatility could be an explanation for why crocodiles survived the meteor impact that wiped out the dinosaurs.  Since crocodiles can’t control their body temperature and rely on the environment for warmth, they generally fare better in warm conditions.  During the age of dinosaurs, the climate was warmer than it is today, which could explain why crocodile diversity was higher.  

The scientists next step is to try to figure out why some prehistoric crocodiles died out while others did not. 

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Why crocodiles have changed so little since the age of the dinosaurs

Photo, posted December 26, 2012, courtesy of Nicholas Smith via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Non-Native Plants And Insect Decline | Earth Wise

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Global insect populations have been in decline since the beginning of the 20th century.  The decline accelerated during the 1950s and 1960s, and it has reached alarming levels during the past 20 years.

The causes of plummeting insect populations include habitat destruction, deforestation, climate change, light pollution, and the rise of industrial agriculture.  This so-called insect apocalypse is being mirrored by a bird Armageddon because so many bird species depend on insects for their diets.

A still controversial, but increasingly likely factor in the decline of insect populations is the spread of non-native plants in agriculture, agroforestry, and horticulture.  A recent study published in the journal Ecological Entomology presents recent data supporting the proposition that the widespread displacement of native plants is a key cause of insect declines. 

Many insects depend on a limited number of plants for survival.  In many cases, insects’ diets are restricted to a single plant family.  When native host plants dwindle or disappear from an area, the population of insects that depend on those plants shrinks.

There are examples of insects that adopt introduced plants as food sources, such as silver-spotted skipper butterfly larvae feeding on invasive kudzu in the eastern U.S.  But generally, the widespread incursion of non-native plants is harmful to native insect populations.

Non-native plants are especially popular for horticulture.  Millions of acres of potential insect habitat have been transformed into food deserts for native insects.  The authors of the recent study recommend that Americans should extensively include native plants in their yards to help preserve insect diversity.

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How Non-Native Plants Are Contributing to a Global Insect Decline

Photo, posted May 2, 2004, courtesy of Bernard Spragg via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Crop Diversity

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A study at the University of Toronto suggests that on a global scale, we are growing more of the same kinds of crops, and this diminishing diversity presents major challenges for agricultural sustainability.

In some places, for example here in North America, crop diversity has actually increased.  Back in the 1960s, North Americans grew about 80 crops.  Now there are 93.

But on a global scale, more of the same kinds of crops are being grown on much larger scales.  Just four crops – soybeans, wheat, rice and corn – occupy nearly 50% of the world’s entire agricultural lands.  The remaining 152 crops cover the rest.  Large industrial farms often grow one crop species – usually just a single genotype – across thousands of acres of land.

This decline in global crop diversity is problematic in several ways.  On a cultural level, it threatens regional food sovereignty.  If regional crop diversity is threatened, it makes it more difficult for people to eat or afford foods that are culturally significant to them.

On an ecological level, the dominance by a few genetic lineages of crops makes the agricultural system increasingly susceptible to pests or diseases.  The deadly fungus that is threatening the world’s banana plantations is a prime current example.  The Irish potato famine in the 19th century is a tragic historical example.

As large industrial-sized farms in Asia, Europe and the Americas start to look more and more alike, the dangers of large monocultures of crops that are commercially valuable will only increase.  It will be important for global governments to consider the impact of policies that affect the diversity of the agricultural system and its sustainability in an increasingly hungry world.

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A small number of crops are dominating globally. And that’s bad news for sustainable agriculture

Photo, posted August 13, 2012, courtesy of Alasdair McKenzie via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Dietary Diversity And Health

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For decades, we have heard from public health sources that we should eat a variety of foods.  Dietary diversity is touted as important for health.  However, there has never really been a consensus about what so-called dietary diversity actually  is, how it is measured, or how it necessarily is healthy.

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Tracking Climate Opinions

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Public opinion about global warming is an important influence on decision making about policies to combat global warming and to be prepared for its consequences.  An extensive polling effort by Yale University has produced an estimate of public opinions down to state, congressional district, and county levels.  

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