Noelle Swan

Posts Tagged ‘University of Delaware’

Getting to the Guts of Autism

In Healthcare on May 6, 2013 at 7:42 pm

This article first was published by the online arm of Delaware’s NPR News Station, on April 29, 2013.

autismTo roughly two million Americans struggling with autism, chronic stomach problems have long been just another side effect. Now, it looks like the issues in their guts could actually be aggravating—or even triggering—their symptoms of autism.

A new arm of autism research has begun to explore the possibility that problems in the gut microbiome—an entire ecosystem of bacteria residing within the digestive tract that is responsible for extracting energy from food—could actually play a role in exacerbating or even causing behaviors and symptoms associated with autism.

While researchers from a variety of disciplines around the world are turning their attention to the stomach, University of Delaware Professor of Chemical and Biomolecular Engineering Prasad Dhurjati is helping to put their work into context.

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Violence halts UD researcher’s snow leopard project in its tracks

In Wildlife and Ecology on February 11, 2013 at 5:42 pm

Snow leopardWhen University of Delaware graduate student Shannon Kachel headed to Tajikistan last summer in search of the endangered snow leopard, he was prepared to contend with rugged terrain, high altitudes, and even possibly Afghan drug and weapons smugglers. However, he did not expect to have to take shelter in a bathtub while government troops swept through the streets and mortar shells streaked by his hostel window.

Kachel was in bed when machine gun fire erupted outside his window.

“I rolled off of the bed and onto the floor then belly-crawled over to the bathtub. I spent 13 hours huddling there with shrapnel and bullets flying through windows, buildings burning, and tanks rolling through the streets below,” he said.

The UD wildlife ecology major had come to Tajikistan two months earlier as part of a research project funded by the University of Delaware and Panthera, an international wildcat conservation organization. He aimed to piece together a rough census of snow leopards, mountainous wildcats known for their gray-white fur and black rosette markings, and to explore the effect of human hunting of hoofed animals, or ungulates, on the predatory cats.

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Underwater robots track sand tiger sharks

In Wildlife and Ecology on November 25, 2012 at 12:56 pm

This article first was published by, Delaware’s NPR News Station on November 25, 2012.

Photo Credit: Tim Sackton

The sand tiger shark’s telltale silhouette and jagged rows of teeth may strike fear into the hearts of aquarium visitors, but Delaware State University fisheries biologist Dewayne Fox thinks this large gray fish with reddish-brown spots on its back is “just absolutely awesome.”

Fox started studying sand tiger sharks in the Delaware Bay in 2006, in an effort to understand why their numbers have declined between 70 and 95 percent in recent years.

This fall, thanks to some high tech support from researchers at the University of Delaware, Fox got his first real-time glimpse of the migration patterns and environmental preferences of these elusive sharks – information that may help him find answers to the shark’s dwindling presence.

Continuing a longtime partnership between Delaware’s two land-grant universities, Fox called upon University of Delaware assistant professor of oceanography Matt Oliver to convert a remote-controlled underwater glider used to monitor water conditions into a satellite receiver and transmitter.

Over the last six years, Fox has tagged more than 500 sand tiger sharks with acoustic transmitters that send radio signals to an array of 70 receivers positioned along the Atlantic coastline as the sharks swim by them.

By combining data gathered through those acoustic transmitters with sightings reported by marine biologists in other coastal states, Fox has started to piece together an outline of the sand tiger shark’s migration habits.

Mother sand tiger sharks seem to prefer to give birth off the coast of the Carolinas. Young pups spend their summers in Cape Cod before graduating to Delaware Bay, Fox said. Both young and adult sand tigers spend the winters in the warmer waters of Florida and the Gulf of Mexico.

“One of the things we have been able to figure out is that the Delaware Bay probably has the largest concentrations of sand tiger sharks in the summer,” Fox said.

The sand tiger sharks likely fill a vital ecological niche at the top of the bay’s food chain, Fox said. Should their numbers continue to decline, he said he worries that the ecosystem as a whole could suffer.

This wouldn’t be the first time the declining shark populations rippled down to impact neighboring species, Fox said. The decline of sand bar sharks in the Chesapeake Bay led to an explosion of cownose rays that in turn decimated the bay’s oyster population, and fractured Maryland’s oyster industry.

While Fox’s acoustic transmitters have provided a rough sketch of the sand tiger sharks’ migration path, many questions linger about what environmental cues might trigger migration and reproduction, Fox said.

That’s where Oliver’s suped-up glider comes in.

Known as OTIS, short for Oceanographic Telemetry Information Sensors, the glider resembles a bright yellow rocket with fins and houses multiple sensors capable of measuring temperature, salinity, oxygen levels, and chlorophyll concentrations in the water.s

Oliver’s adaptation can also pick up signals given off by special Radio Frequency Identification (RFID) tags attached to marine animals, alter its course to follow those animals, and head to the surface to place a satellite telephone call to Oliver’s lab with information about which animals it has encountered and the corresponding environmental conditions.

“The idea is to actually get the data that shows what types of water conditions sharks are using so that you can eventually build a model and make predictions based on water parameters,” Oliver said.

University of Delaware graduate student of oceanography Danielle Haulsee also helped to broaden the kind of information available to Fox by internally implanting sand tiger sharks with VEMCO mobile transceivers (VMTs).

These high-tech tags are capable of not only transmitting their location but also of receiving information from other VMTs implanted in other marine life, such as other sharks, striped bass, or sturgeon.

“[I]f anything with a [VMT] tag swims by a shark, it can pick that up and tell us about it. By looking at the data that comes from those tags, you can start to see not only where the shark goes but what else is around that shark,” Haulsee said.

Haulsee received special training from marine veterinarians from the Georgia Aquarium to surgically implant VMT tags into sand tiger sharks. This summer, she, Fox, and Oliver headed out into the bay fishing for sharks.

The three drew sand tiger sharks alongside the boat, one at a time, in a kind of underwater stretcher that folds around the animal and holds it in place just under the surface of the water. Haulsee made a small incision in the abdomens of 20 sand tiger sharks, placing tags in the body cavity, before stitching them back up and sending them on their way.

Fox hopes that gathering diverse data about sand tiger sharks from OTIS and the VMT tags could not only expand knowledge about sand tiger shark behaviors and habits, but also lead to the identification and reduction of factors that might be contributing to their decline.

However, because sand tiger sharks have one of the lowest reproductive growth rates of all sharks, recovery likely will be slow.

Female sand tiger sharks do not fully mature until their teens and typically only live until they are around 25 years old. Sand tiger embryos begin learning to hunt in the womb, first eating unfertilized eggs, and then their would-be siblings until only one remains. Females give birth to a single pup every two years or more. That means a single female probably will only have four pups in her lifetime.

“This is an animal that even if everything is right, it’s going to take a long time for them to come back,” Fox said.

UD Apiary research aims to take sting out of nationwide bee colony collapse

In Honeybees, Wildlife and Ecology on August 2, 2012 at 1:56 pm

This article first was published by, Delaware’s NPR News Station on August 2, 2012.

Bee colonies across the country began mysteriously collapsing in 2006, and have had scientists urgently seeking a cause of the meltdown ever since. Now, researchers at the University of Delaware believe they’ve uncovered clues to solving this problem that threatens the delicate natural balance on which the nation’s food supply depends.

At UD’s Newark apiary, where 22 hives are home to more than 1.3 million bees, researchers are focusing on an invasive parasite that can be as devastating to a bee colony as its Latin name, Varroa destructor, implies. The mites are one of several culprits that may be combining to cause Colony Collapse Disorder, which has resulted in the die-off of tens of billions of bees nationwide.

Debbie Delaney, a UD assistant professor of entomology and wildlife ecology, says combating one possible source of the decline might be as simple as mimicking a bee’s natural behavior, at least for small-scale beekeepers like the 300 apiarists in Delaware who host the majority of the state’s honeybees in their backyards.

While State Apiarist Robert Mitchell describes the status of the honeybee population in Delaware as “adequate,” he adds that colony losses have taken a toll at a time when the demand for pollination services continues to grow.

“Honeybees are responsible for the pollination of $10 million worth of wholesale fruit and vegetable value in the state,” said Secretary Ed Kee of the Delaware Department of Agriculture in an email reply. “This valuable resource must be protected.”

UD Apiary research aims to take sting out of nationwide bee colony collapse
Various stages of varroa mites.
Photo by Zachary Huang,

The varroa mite is one of the “primary forces behind the decline of the honey bees,” said Katy Evans, a UD graduate student spearheading Delaney’s study.

These little external parasites attack both adult honeybees and their brood, or young, by latching onto them and feasting on their blood. That may sound familiar to people used to swatting at mosquitoes, but varroa mites are no minor nuisance.

Although we can just barely see them with the naked eye, Delaney explains that it is a whole different story from a bee’s perspective.

“It’s as if we had a dinner plate attached to us sucking our blood,” she said.

To get to that blood, mites have to penetrate the bee’s exoskeleton, leaving behind a wound that is open to infection from additional pests and pathogens. When feeding on drones, or male bees, the mites deplete the drones’ protein and sperm levels and eventually render the bee incapable of flying. In addition to feeding on drones, the mites attach themselves to the brood of young bees in the early stages of their development.

“To make it even more awful, they vector viruses,” Delaney added. Just like a mosquito carrying malaria, or a tick bearing lime disease, these mites can transport and deliver new diseases directly into their hosts’ bloodstreams.

Delaney’s research at the UD apiary stems from observations she made in her backyard hives. So far, her bees have been healthy: no signs of virus, good honey production, and a strong population. She says that some of her bees have varroa mites, but they haven’t damaged the colony overall. She believes that the few mites on her bees at home have not had a chance to multiply because she employs a technique called hive splitting, which is modeled after bees’ natural tendency to swarm and establish two separate hives if their population outgrows the hive.

UD Apiary research aims to take sting out of nationwide bee colony collapse
Bee larva with 5 varroa mites on one side.
Photo by Zachary Huang,

Delaney is currently testing a theory that some natural beekeepers have claimed for years. During a hive-splitting period, bees don’t reproduce, and varroa mites have no baby bees to feed on. So the mite population dies off and takes so long to rebound that they never achieve numbers large enough to harm the colony.

Bill Leitzinger, amateur apiarist from Middletown and president of the Delaware Beekeepers Association has used the hive-splitting technique to control varroa mites in his hives for ten years. Leitzinger says when he was growing up, his father used chemicals to address mites and other problems around his few hives. He decided to do things differently.

“I have never used chemicals,” he said. “It used to be I was the weird one. Now most beekeepers are trying not to use chemicals.” He noted that the natural beekeeping movement evolved in response to research showing that chemicals applied to the hive can seep into the wax and remain in the hive for several years.

Delaney points out that miticides are not the only chemicals that remain in the wax. Pesticides and fungicides applied to plants miles away can stick to honeybees’ bodies during nectar collection and hitch a ride back into the hive where they, too, remain in the wax for years to come.

Recent research indicates that insecticides and parasites in non-lethal amounts can have a combined effect that becomes lethal. Delaney speculates that the combination of miticides and insecticides could have a similar effect. She hopes that her research will confirm that hive splitting is a viable alternative to chemical miticide application.

“If we can reduce in any possible way any type of pest that gets into the hive matrices or that the bees come in contact with, then I think that’s a very good thing,” Delaney said.

Plastics in the Ocean May Be Grossly Underestimated

In Marine Ecology, Wildlife and Ecology on May 2, 2012 at 4:44 pm

This article first was published online by DFM News on May 2, 2012.

Photo Credit: Sea Education Association, Marilou Maglione

Surface trawling has long been used to estimate the level of plastic pollution in the ocean, from plastic soda bottles to disposable bags, but it turns out this method of measurement only scratches the surface of the problem… quite literally.

High winds cause plastic debris to mix well below the surface where more than half of the ocean’s plastic pollution has swirled about, uncounted, according to Tobias Kukulka, a University of Delaware assistant professor of physical ocean science and engineering.

In still water, plastic is buoyant, inevitably rising to the ocean surface, Kukulka explained in an email interview. “However, in a wind-driven turbulent ocean, this buoyant upward transport is balanced by a downward transport because plastic particles “catch a ride” with the turbulent motion,” he said.

Kukulka and co-lead author Giora Proskurowski, oceanography scientist at the University of Washington, published the results of a study of plastic pollution of the world’s oceans in the latest issue of Geophysical Research Letters.

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