Curio Cabinet

With spring comes gardening, but these “gardeners’ best friends” have been hiding a dastardly secret. Believe it or not, practically all earthworms in North America are invasive. Many worm species, originally brought to the continent from Europe and Asia, are doing active harm to forests in the U.S. and Canada. Oddly, some of the same traits that make worms so helpful to gardens make them a devastating force in wild forests.
 
At first glance, worms may seem like simple creatures with little destructive potential. They have no eyes. Their brains contain a mere 300 or so neurons, compared with a dog’s 530 million. Worms have a simple body layout, sometimes described as a “tube in tube” system: a digestive tube inside a muscular tube, with five heart-like organs called aortic arches to pump their blood. Once upon a time, there were many native species of earthworms in North America. Their demise came not by man-made means, but by unprecedented natural events. Around 15,000 years ago, during the ice age of the Pleistocene epoch, glaciers formed over much of North America. This included Canada and the northern United States, stretching as far south as midwestern states like Illinois and Ohio. The glaciers eroded soil, severely impacting native earthworm populations. Around 3,700 years later, as the ice age ended, the glaciers retreated. This left behind a lot of barren land that gradually grew into worm-free ecosystems. Trees and other plants in these areas evolved to live without worms, meaning that they were adapted for a particular kind of soil, with particular levels of nutrients like nitrogen, phosphorus, and potassium. Things were going great until explorers, traders, and settlers from Europe and Asia brought new worms to North America with them. The wriggly invaders likely hid out in the roots of imported crops and other organic materials. These included several species in the Acanthodrilidae family and the Lumbricidae family, which today make up the majority of earthworms in North America.
 
In the confines of a garden, non-native worms help aerate soil with their tunneling. Their droppings, called castings, are water-soluble, so plants that live in soil with a lot of castings can more easily absorb water. In a forest, however, trees and native plants have adapted to live in dryer soil with fewer nutrients. When worms move in, the soil changes, and invasive plants often reap the benefits while trees and other native plants suffer. Worms also love to eat leaf litter—dead leaves on forest floors which would otherwise compost into soil. This causes many species of insects, which rely on the leaf litter for shelter and food, to die out. Even some bigger species, like salamanders, can’t survive without adequate leaf litter. With fewer insects, many kinds of birds can’t survive. From top to bottom, invasive worms affect every part of an ecosystem they touch. In an interview with The Atlantic, Anise Dobson, a forest ecologist at Yale University, said of the worm invasion, “If you were to think about the soil food web as the African savanna, it’s like taking out all the animals and just putting in elephants—a ton of elephants.”
 
So, can anything be done to stop these tunneling troublemakers? There are no easy answers, since pesticides can’t be used in forests, and removing invasive species is notoriously difficult once they’re well-established. For now, some ecologists suggest that people hiking or traveling through forests check their shoes before entering and after leaving, to prevent further spread of worms. Education and outreach can also help ensure that people don’t release worms used for fishing bait into wild areas. Here’s hoping that we can avoid a worm-pocalypse.

 
[Image description: An earworm crawls on top of soil.] Credit & copyright: PortalJardin, Pixabay

It's Flashback Friday! This week we’re throwing things waaay back with these curios all about ancient times and practices.
 
Alright, who ordered the roast duck and cauliflower skewers with a side of Mount Vesuvius eruption? This past month, archaeologists uncovered a frescoed street food stand in the ancient city of Pompeii near Naples, Italy. The well-preserved artifact was known then as a thermopolium or "hot drinks counter" in Latin. There is a fresco painting of a sea nymph in blue hues to the left of the stall; at the forefront are images of chickens and ducks which may indicate what was on the menu in 79 C.E.: remnants of poultry as well as pig, goat, and snails were found in clay pots at the site along with containers for wine. Researchers have uncovered about 165 acres of Pompeii's remains, which were buried under Mount Vesuvius' volcanic debris. The food stalls and their contents will provide further insights into the daily diets of ancient Roman culture. But what we really want to know is what time the food chariots came around to serve lunch!
 

Image credit & copyright: Pompeii Archaeological Park/Ministry of Cultural Heritage and Activities and Tourism/Luigi Spina/Handout via REUTERS

Scientists are really shooting for the moon with these plants. Researchers at the University of Florida were recently able to grow plants on Lunar soil collected during the Apollo missions, according to a paper published in Communications Biology. The soil used is Lunar regolith, which is powdery and razor-sharp at the microscopic level. That’s challenging enough when cultivating crops, but the scientists also had a limited quantity of the soil. After several attempts to acquire Lunar regolith from NASA, the agency finally loaned them just 12 grams to be used in their experiments. To make the most of the soil, the scientists created thimble-sized wells filled with 1 gram each. They then planted arabidopsis, also known as thale cress, along with a mix of nutrients and water. Surprisingly, the plants were able to sprout in the alien soil, although they did appear to struggle compared to the control group. The sprouts in the Lunar regolith tended to grow slower and were smaller in size. Most importantly, the scientists were able to deduce how the plants reacted to the stressful environment at the genetic level. Lead author Anna-Lisa Paul told Science News, “By seeing what kind of genes are turned on and turned off in response to a stress, that shows you what tools plants are pulling out of their metabolic toolbox to deal with that stress.” This means that, if humanity ever does create livable colonies on the moon, plants might be able to be genetically engineered to grow better there. Such plants could provide oxygen and food to lunar explorers. Now that would be some out-of-this-world horticulture.

[Image description: Bean sprouts grow inside small cups.] Credit & copyright: KlausAires, Pixabay
 

This place is a hole. Literally! Cave explorers in China have found a massive sinkhole in the Guangxi Zhuang Autonomous Region that is home to an ancient forest. The area is known for large limestone formations, and caves and sinkholes in the region are common. Sinkholes are formed when water erodes away at the limestone, and in this case, the culprit is an underground river system. While sinkholes are a common occurrence, it’s rare to find one large enough to contain its own forest. In China, there are around 29 other known sinkholes like this, called Tiankeng, which means “heavenly pit” in Mandarin. This particular sinkhole appears to be about 500 feet wide, 1000 feet long and 630 feet deep. It’s so big that it took explorers hours to safely rappel down around 330 feet before trekking into the sunken forest.
 
Despite the size of the hole, there isn’t much sunlight at the bottom because of the limited angle at which light can enter from above. Nevertheless, the trees in the underground forest grow up to 130 feet, seemingly well-adapted to their unusual environment. On the forest floor are shade plants that fill every nook and cranny, potentially hiding future discoveries. Chen Lixin, the leader of the expedition that discovered the massive sinkhole, believes there might be undiscovered species lurking in the enclosed ecosystem. Lixin told the press, "I wouldn't be surprised to know that there are species found in these caves that have never been reported or described by science until now.” Lixin’s team was sent from the Institute of Karst Geology of the China Geological Survey. Its sister institute in the U.S. is the National Cave and Karst Research Institute (NCKRI). NCKRI’s executive director, George Veni, explained that China’s karsts, or limestone landscapes featuring heavily eroded areas, are different than those found in other parts of the world . "So in China you have this incredibly visually spectacular karst with enormous sinkholes and giant cave entrances and so forth. In other parts of the world you walk out on the karst and you really don't notice anything. Sinkholes might be quite subdued, only a meter or two in diameter. Cave entrances might be very small, so you have to squeeze your way into them." Sounds like China really is heavenly for sinkhole explorers.

 
[Image description: The Xiaozhai Tiankeng, the world's deepest sinkhole, in Chongqing Municipality, China.] Credit & copyright: Brookqi, Wikimedia Commons, image cropped for size, Public Domain

This is a big step toward helping little ones. Scientists might be moving closer to solving the mystery behind one of the most tragic syndromes known to man: Sudden Infant Death Syndrome (SIDS). Australian researchers recently published a study in eBioMedicine claiming that they’ve found the first ever biomarker, or genetic indicator, for SIDS. The Mayo Clinic defines SIDS as the unexplained death of an infant under one year old, usually during sleep. Past studies have not shown any genetic links, although SIDS is more likely to affect an infant who has had closely related family members die of it. It is also more likely to affect infants who are born premature, born to mothers under 20, or who live in a household where someone smokes. Around 3,400 babies die from it every year in the U.S. alone, and parents have long been desperate for answers on how to prevent it.
 
In this new line of research, scientists examined blood samples from infants that had died from SIDS, specifically to measure the levels of Butyrylcholinesterase (BChE), an enzyme in the cholinergic system, part of the body’s autonomic system that controls things like sleep, wakefulness, and blood pressure. They found that in the samples from infants that had died from SIDS, the BChE activity was lower than in healthy infants. This marks the very first measurable factor that can be tied to SIDS. In a press release by the Sydney Children's Hospitals Network, lead author of the study, Dr. Carmel Therese Harrington, stated, “Babies have a very powerful mechanism to let us know when they are not happy. Usually, if a baby is confronted with a life-threatening situation, such as difficulty breathing during sleep because they are on their tummies, they will arouse and cry out. What this research shows is that some babies don't have this same robust arousal response.” While this finding doesn’t yet point to a cure for SIDS, and there is currently no test available to search for low BChE in living infants, at least some light is finally being shed on this dark subject.

 
[Image description: An infant’s hand clutches and adult’s finger.] Credit & copyright: RitaE, Pixabay