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An anti-malaria breakthrough

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The deadliest animal in the world is the mosquito.  Mosquitos infected 263 million people with malaria in 2023, leading to 600,000 deaths, 80% of which were children.  Malaria is caused by infection from Plasmodium parasites.  The parasites are transmitted to humans from the bite of infected female mosquitos.

Researchers at the University of California San Diego, Johns Hopkins University, UC Berkeley, and the University of Sāo Paulo have developed a new method that genetically blocks mosquitos from transmitting malaria.

The study was published in the journal Nature.  They used gene editing to change a single molecule within mosquitos.  The genetically altered mosquitos can still bite people with malaria and can still acquire parasites from their blood, but the parasites can no longer be spread to other people.  The switching of one specific amino acid known as L224 with a genetic alternative called Q224 prevents malarial parasites from reaching the salivary glands of the mosquito, thereby preventing the spread of infection.  In extensive tests, the researchers found that while the genetic switch disrupted the parasite’s infection capabilities, the mosquitos’ normal growth and reproduction remained unchanged.

The hope is that the replacement of a single amino acid in mosquitoes that prevents them from being infected with malarial parasites is a beneficial trait that can spread throughout a mosquito population.  The researchers believe that the trait can be spread across diverse mosquito species and populations and can pave the way for adaptable, real-world strategies to control malaria.

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Stealth Genetic Switch in Mosquitoes Halts Malaria Spread

Photo, posted June 20, 2014, courtesy of John Tann via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Polar bear population decline

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Researchers from the University of Toronto have directly linked the population decline in polar bears living in Canada’s Western Hudson Bay to climate change.  Between 1979 and 2021, the polar bear population in this region has declined by nearly 50%.

The monitoring data over this period shows that the average size of polar bears has declined, the size of cub litters has dropped, and cub survival rates are reduced.

The primary factor is the declining amount and duration of sea ice.  When there is less ice, bears have less feeding time and less energy overall.  The loss of sea ice means that bears spend less time hunting seals and more time fasting on land.  The lack of food leads to reduced reproduction, cub survival, and, ultimately, population decline. 

The average body mass of adult females has dropped by 86 pounds and of cubs by 47 pounds.  With shorter hunting periods and less food, mothers produce less milk.  Not only have cub litter sizes dropped over the monitoring period, but mothers are keeping their cubs longer because they are not strong enough to live on their own.  The bottom line is that the survival of cubs directly impacts the survival of the population.

Western Hudson Bay is considered to be a bellwether for polar bear populations globally.  It is one of the southernmost populations of polar bears and it has been monitored for a long time.  With the Arctic warming at a rate four times faster than the global average, polar bear populations in other Arctic regions are likely to be experiencing similar declines. 

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Polar bear population decline the direct result of extended ‘energy deficit’ due to lack of food

Photo, posted October 23, 2015, courtesy of Anita Ritenour via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Growing safer potatoes

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We are often advised to avoid eating green areas on potatoes.  The green comes from chlorophyll that occurs naturally when potatoes are exposed to light.  It is harmless but when it is there, it can be accompanied by a natural toxin – a substance called solanine, which is a steroidal glycoalkaloid or SGA.  Sunlight can produce solanine as well as chlorophyll.  Solanine is produced by plants to protect them from insects. 

Solanine is bitter tasting so one is unlikely to consume much of it.  But consuming enough of it can lead to gastrointestinal complications like diarrhea, abdominal pain, vomiting, and sweating. 

Researchers at the University of California Riverside have discovered a way to eliminate toxic compounds from potatoes, making them safer to eat and easier to store.  They have identified a key genetic mechanism in the production of SGAs.  They found a specific protein that controls the production and believe it will be possible to control where and when SGAs are produced.  Thus, it may be possible to have SGAs present in the leaves of potato plants, thereby protecting them from insects, while having none in the potatoes themselves.  By limiting SGAs to non-edible parts of plants, they can be safer and more versatile plants.  For example, modified potatoes could be stored in sunny places without worry and would always be safe to eat.

Plants have evolved ingenious ways to balance growth, reproduction, and defense.  Our growing understanding of these mechanisms can allow people to redesign crops to meet modern needs, increase food safety, and reduce food waste.

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Growing safer spuds: Removing toxins from potatoes

Photo, posted October 14, 2013, courtesy of Elton Morris via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Climate change and an iconic Florida bird

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The Florida scrub-jay is a medium-sized bird native to Florida, known for its striking blue plumage and distinctive call. It is the only bird species that is entirely endemic to Florida, found mainly in the scrubby, sandy habitats of the central and southern part of the Sunshine State.

But extensive development, habitat fragmentation, and habitat degradation have caused the scrub-jay population to decline significantly over the past century. 

Another threat facing the Florida scrub-jay is climate change.  According to a new study by researchers from the Archbold Biological Station and the Cornell Lab of Ornithology, warmer winters driven by climate change are causing Florida scrub-jays to nest one week earlier than they did in 1981.  This seemingly innocuous change has reduced the number of offspring raised annually by 25% since 1981. 

The research team examined 37 years of data to assess the impacts of warming on reproductive efforts.  From 1981 to 2018, the average winter temperature at Archbold Biological Station in Florida increased by 2.5 degrees Fahrenheit.  Despite increases in the number of nests built and eggs laid over the longer breeding season, Florida scrub-jays are not producing more young. 

The researchers hypothesize that warmer temperatures make the nests susceptible to predation by snakes for a longer period of the Florida spring than in the past.  The findings, which were recently published in the journal Ornithology, suggest that climate change could dampen the success of conservation efforts for this threatened species.

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Long-term study reveals warming climates threaten Florida scrub-jay

Florida Scrub-Jay

Photo, posted October 15, 2018, courtesy of Judy Gallagher via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Tracking down PFAS toxins

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PFAS – per- and polyfluoralkyl substances – are a group of organic compounds that have been extensively used to provide water-, oil-, and dirt-resistance to a wide range of products ranging from non-stick pans, clothing, and packaging to paint, car polish, and fire-suppressant foam.  Exposure to specific PFAS compounds is associated with multiple adverse health effects, including altered immune and thyroid function, liver disease, kidney disease, poor reproductive and developmental outcomes, and cancer.  PFAS compounds do not break down in the environment and therefore, over time, become concentrated in plants, animals, and people.

Government agencies such as the EPA in this country and the EU have set strict limits for allowable levels of PFAS in drinking water.  Testing water for the trace amounts of PFAS that constitute the limits is time-consuming and expensive and requires complex equipment and experienced personnel.

Researchers at MIT have now introduced a technique for making a portable, inexpensive test that can easily and selectively detect PFAS in water samples.  The test makes use of a special polymer containing fluorinated dye molecules that cause the polymer to fluoresce red.  If PFAS are present in the sample, they enter the polymer and displace the dye molecules and switches off the red fluorescence. 

The new technique is suitable for on-site detection in highly contaminated regions.  Detecting smaller concentrations can be achieved with sufficient precision after pre-concentrating the samples using the process of solid-phase extraction.

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Tracking down Environmental Toxins

Photo, posted October 16, 2021, courtesy of Nenad Stojkovic via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Wild pigs in the U.S.

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In the U.S., there are as many as nine million feral swine living in 38 states.  A conservative estimate indicates that they cause about $1.5 billion in property and agricultural damage each year in this country. 

Pigs were introduced to the United States centuries ago as a food source, but they quickly established wild populations. Feral domestic pigs bred with purebred Eurasian boar that were introduced for hunting, and these hybridized wild pigs spread across the landscape thanks to their prolific reproductive rates and willingness to eat just about anything.

When wild pigs forage, they upturn roots and soil with their snouts, damaging natural habitats and other animals. A 2021 study found that wild pigs are releasing over five million tons of carbon dioxide annually by uprooting carbon trapped in soil. 

As a result, many programs were implemented nationwide to try to reduce populations, usually through lethal methods. 

According to new research from the University of Georgia’s Savannah River Ecology Laboratory and Warnell School of Forestry and Natural Resources, recent conservation efforts have proven effective at controlling wild pig populations in the Southeastern U.S.  Within 24 months of the start of control efforts in the study area in South Carolina, the research team found a reduction of about 70% in relative abundance of pigs, and a corresponding decline in environmental rooting damage of about 99%.

Wild pigs are basically a human-caused problem, and controlling their populations will require continued cooperation and collaboration. 

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Wild pig populations in U.S. can be managed

Wild Pigs And The Environment

Photo, posted January 28, 2013, courtesy of Don and Janet Beasley via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Shrinking Birds | Earth Wise

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A new study by researchers at Yale University looks at the way bird morphology is changing in response to the warming climate.  As temperatures rise, birds’ bodies are growing smaller, but their wings are growing longer.

In the study, published in the Proceedings of the National Academy of Sciences, the scientists analyzed two independently collected datasets containing 40 years of morphology changes in 129 bird species comprising 52 migratory species in North America and 77 South American species.

In both datasets, similar changes were observed over the 40-year period.  The overall trend makes sense given that being smaller and having longer wings both would help birds to stay cool in warmer weather.  What was less obvious was that the changes to the birds were much greater among the smallest bird species.

One possible explanation is that smaller species tend to reproduce on a shorter time scale and therefore evolve more quickly.  However, the study found no link between generation length and the changes in body size.

Another possible explanation is that smaller species tend to have larger populations, which means there is a greater chance of having individuals with desirable new traits that can get passed on.  But the scientists found no link between population size and shifts in body size either.

At this point, it is unclear why smaller birds are shrinking more.  More research is needed to figure out why larger birds are slower to adapt to climate change.  In general, larger species of animals have an increased risk of extinction.  This new research suggests that larger body size exacerbates extinction risk by limiting the ability for birds to adapt to the changes we are making to the climate.

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Birds Are Shrinking as the Climate Warms — and Small Birds Are Shrinking Faster

Photo, posted October 30, 2018, courtesy of N. Lewis / National Park Service via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Heatwaves And Bird Populations | Earth Wise

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The increased occurrence and intensity of heatwaves around the world is affecting most living things.  Heatwaves can be lethal for warm-blooded animals – including people – but the behavioral and physiological effects of sub-lethal heat have not been extensively studied.  Heat that doesn’t kill animals can still impact their ability to adapt and thrive as the climate changes.

Researchers at the University of Tennessee in Knoxville recently published a new study that examined how heat impacts the behavior and physiology of Zebra finches.  They exposed the birds to a four-hour heat challenge, similar to what wild birds might experience during a hot summer afternoon.   They used Zebra finches because these songbirds experience extreme temperature fluctuations in their native Australia.

The team measured heat effects on thermoregulatory behavior, how heat alters gene activity in tissues critical to reproduction, and how heat affects the area of the brain that controls singing.  The evidence showed that even sub-lethal heat can change a bird’s ability to reproduce both from the functioning of its reproductive system and its motivational circuits for mating behavior.

The researchers found that some individual birds were better able to minimize the physiological effect of heat, for example by adjusting their behavior to dissipate heat.  Some individuals and even some species are likely to be able to adapt to increasingly extreme temperatures.

Global bird populations have been dramatically declining over the past few decades.  Previous studies have shown that birds sing less during heatwaves. Based on the new study, it appears that increasing heatwaves may be a potential underlying mechanism for the decline in bird populations.

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New Research Suggests Heat Waves Could Lead to Avian Population Decline

Photo, posted August 22, 2017, courtesy of Dennis Jarvis via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

American Robins And Climate Change | Earth Wise

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American robins are migratory songbirds that can be found throughout much of North America.  Named after European robins because of their reddish-orange breast, American robins are often found hopping across lawns and nesting on porches.  Their rich caroling is among the first pre-dawn bird songs heard in spring and summer.  

While some overwinter in northern parts of the United States and southern Canada, most American robins migrate south to overwinter in places like Florida and the Gulf Coast, as well as central Mexico and the Pacific Coast.  They typically head south by the end of August and return north sometime between February and March to their breeding grounds in Canada and Alaska.  They spend their short time there trying to find a mate, build a nest, raise a family, and consume enough food to sustain themselves on their long return journey south.

But climate change is making these seasonal rhythms less predictable.  According to a new study recently published in the journal Environmental Research Letters, American robin migration is kicking off earlier by about five days each decade.  The birds now migrate 12 days earlier than they did in 1994.  

For 25 years, researchers at Canada’s Slave Lake have been recording the timing of American robin spring migration.  They attached GPS devices to 55 robins, tracking their movements from April through June. The researchers linked the birds’ movement with weather data, including air temperature, snow depth, wind speed, and precipitation.  The results showed that robins start migrating north earlier when winters are warm and dry. 

Understanding the influence over the timing of migratory events is important because the timing of migration can influence reproductive success.

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A Migration Mystery

American robins now migrate 12 days earlier than in 1994

Photo, posted January 1, 2020, courtesy of Becky Matsubara via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Tough Times For Fireflies | Earth Wise

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Fireflies or lightning bugs are soft-bellied beetles known widely for their use of bioluminescence – the biochemical emission of light – to communicate and to attract mates.  There are more than 2,000 species of these beetles globally.  They can be found in temperate and tropical climates, like marshes or wet, wooded areas, all throughout the world.   

But if you are seeing fewer fireflies each summer, you’re not alone.  Like many insects, firefly populations are under duress from threats like pesticides, pollution, and habitat loss.  But fireflies are also facing another threat unique to luminous bugs: light pollution.  Light pollution is making it harder for fireflies to reproduce because the artificial light is outshining their mating signals. 

Male fireflies light up to signal availability and female fireflies respond with patterned flashes to indicate they’re interested.  But artificial bright light from things like billboards, streetlights, buildings, and homes, is interfering with the fireflies reproduction communications. 

The study, by researchers at Tufts University and the IUCN, warned that these threats facing fireflies could lead them globally to extinction. 

The researchers also point to habitat loss as another major threat to fireflies.  Firefly populations are especially vulnerable because they need special conditions to complete their life cycle.  Mangrove forests and marshes around the world are being removed in favor of cash crops like palm oil.   

Insects like fireflies are crucial components of many ecosystems where they perform important functions, like aerating soil, pollinating plants, and controlling pests.  Firefly larvae feed on snails, slugs and mites, and many fireflies are effective pollinators. 

We can’t afford for fireflies to go dark. 

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A Global Perspective on Firefly Extinction Threats

Fireflies Have a Mating Problem: The Lights Are Always On

Photo, posted June 5, 2010, courtesy of Matt MacGillivray via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Climate Change And Dolphins

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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.

Thoreau And Climate Change

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Henry David Thoreau was a 19th-century American naturalist, philosopher, poet, essayist, and social reformer.  He is best known for “Civil Disobedience,” an essay advocating for the rebellion against an unjust government, and for “Walden,” a book about his experiences living simply in nature.  Now, Thoreau’s observations from “Walden” are the foundation of a new study exploring the effects of climate change on tree leaf-out and the emergence of spring wildflowers. 

This research, which was recently published in the journal Ecology Letters, relies on Thoreau’s scientific observations gathered during the 1850s when he spent 26 months living in isolation at Walden Pond in Concord, Massachusetts.  These observations from Thoreau were combined with current research to measure tree and wildflower leaf-out dates for 37 different years between 1852 and 2018.  “Leaf out” refers to the time in spring when plants and trees begin producing leaves.  An alteration in this timing can have a domino effect throughout an ecosystem.

Over the past century, temperatures in Concord, Massachusetts have warmed five degrees Fahrenheit.  As a result, leaf-out dates have changed significantly.  According to researchers, wildflowers are leafing out about one week earlier, while trees are leafing out about two weeks earlier than they did 160 years ago. 

Ground-dwelling plants like wildflowers have a narrow window to accomplish growth, photosynthesis, and reproduction, before the canopy trees leaf out and block the sunlight.  Temperature-driven shifts in the timing of tree leaf-out between Thoreau’s time and now are likely already hindering wildflower abundance and flowering. 

As the climate continues to warm, the already small window of time between wildflower emergence and tree leaf-out will likely shorten further. 

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Using Thoreau, scientists measure the impact of climate change on wildflowers

Photo, posted August 13, 2008, courtesy of Adam Pieniazek via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

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