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Dolphins Suffering From Lung Disease Due to BP Gulf Oil Spill

Dolphins Suffering From Lung Disease Due to BP Gulf Oil Spill

Bottlenose dolphins in Louisiana’s Barataria Bay have lung damage and adrenal hormone abnormalities not previously seen in other dolphin populations, according to a new peer-reviewed study published today in the journal Environmental Science & Technology.

The Deepwater Horizon spill heavily oiled Barataria Bay. The study was conducted in August 2011 as part of the Natural Resource Damage Assessment (NRDA) by a team of government, academic and non-governmental researchers. In the NRDA process, federal and state trustee agencies working cooperatively with BP identify potential injuries to natural resources and lost public uses resulting from the spill, along with restoration projects to ensure that the public is fully compensated for its loss.

Following the Deepwater Horizon oil spill, numerous dolphins were documented encountering oil, such as those in this photo from July 2010.

The publication details the first evidence that dolphins in heavily oiled areas are exhibiting injuries consistent with toxic effects observed in laboratory studies of mammals exposed to petroleum hydrocarbons. The dolphin health study concludes that the health effects seen in the Barataria Bay dolphins are significant and likely will lead to reduced survival and ability to reproduce.

Twenty-nine of the total 32 dolphins sampled in Barataria Bay received comprehensive physical examinations, including ultrasound examinations to assess lung condition. The researchers assigned almost half (48 percent) of the dolphins a guarded or worse prognosis. In fact, they classified 17 percent as being in  poor or grave condition, meaning the dolphins were not expected to survive.

These findings are in contrast to dolphins sampled in Sarasota Bay, FL, an area not oiled by the Deepwater Horizon spill. For Dr. Lori Schwacke, the study’s lead author and veteran of a number of similar dolphin health studies across the southeast, the findings are troubling: “I’ve never seen such a high prevalence of very sick animals—and with unusual conditions such as the adrenal hormone abnormalities.”

The NRDA researchers found that moderate to severe lung disease was five times more likely in the Barataria Bay dolphins, with symptoms including lung masses and consolidation. The researchers also found that 25 percent of the Barataria Bay dolphins were significantly underweight and the population overall had very low levels of adrenal hormones, which are critical for responding to stress.

The researchers examined alternative hypotheses for the dolphins’ disease conditions, such as exposure to other man-made chemicals that have previously been measured in high concentrations in marine mammals and also associated with impacts on health. Blubber samples from the Barataria Bay dolphins, however, showed relatively low concentrations for the broad suite of chemicals measured, including PCBs and commonly detected persistent pesticides, as compared to other coastal dolphin populations.

Based on the findings from the 2011 dolphin health study, researchers performed three additional health assessments in 2013 as part of the Deepwater Horizon NRDA. The studies were repeated in Barataria Bay and Sarasota Bay, and also expanded to Mississippi Sound, including both Mississippi and Alabama waters. Results from these more recent health assessments are still pending.

Researchers conducting the NRDA studies are collaborating closely with the team conducting an Unusual Mortality Event (UME) investigation in the northern Gulf of Mexico under the Marine Mammal Protection Act. Investigations of this type follow stranding events that are unexpected, involve a significant die-off and demand an immediate response.  The observed increase in the number of dolphin strandings now includes more than 1,050 animals that have stranded along the Gulf Coast from the Texas/Louisiana border through Franklin County, FL. Ninety-four percent of these animals have stranded dead.

The UME investigation, spanning from February 2010 to present, is the longest UME response since 1992, and includes the greatest number of stranded dolphins in an UME in the Gulf of Mexico.

Dr. Teresa Rowles, lead for the Marine Mammal Health and Stranding Response Program and a co-author on the dolphin health publication, indicates that “these dolphin health studies will contribute significant information for both the NRDA and the UME investigation as we compare disease findings in the wild, living dolphins to the pathologies and analyses from the dead animals across the northern Gulf.”

Visit EcoWatch’s BIODIVERSITY page for more related news on this topic.

A net-casting ogre-faced spider. CBG Photography Group, Centre for Biodiversity Genomics / CC BY-SA 3.0

Just in time for Halloween, scientists at Cornell University have published some frightening research, especially if you're an insect!

The ghoulishly named ogre-faced spider can "hear" with its legs and use that ability to catch insects flying behind it, the study published in Current Biology Thursday concluded.

"Spiders are sensitive to airborne sound," Cornell professor emeritus Dr. Charles Walcott, who was not involved with the study, told the Cornell Chronicle. "That's the big message really."

The net-casting, ogre-faced spider (Deinopis spinosa) has a unique hunting strategy, as study coauthor Cornell University postdoctoral researcher Jay Stafstrom explained in a video.

They hunt only at night using a special kind of web: an A-shaped frame made from non-sticky silk that supports a fuzzy rectangle that they hold with their front forelegs and use to trap prey.

They do this in two ways. In a maneuver called a "forward strike," they pounce down on prey moving beneath them on the ground. This is enabled by their large eyes — the biggest of any spider. These eyes give them 2,000 times the night vision that we have, Science explained.

But the spiders can also perform a move called the "backward strike," Stafstrom explained, in which they reach their legs behind them and catch insects flying through the air.

"So here comes a flying bug and somehow the spider gets information on the sound direction and its distance. The spiders time the 200-millisecond leap if the fly is within its capture zone – much like an over-the-shoulder catch. The spider gets its prey. They're accurate," coauthor Ronald Hoy, the D & D Joslovitz Merksamer Professor in the Department of Neurobiology and Behavior in the College of Arts and Sciences, told the Cornell Chronicle.

What the researchers wanted to understand was how the spiders could tell what was moving behind them when they have no ears.

It isn't a question of peripheral vision. In a 2016 study, the same team blindfolded the spiders and sent them out to hunt, Science explained. This prevented the spiders from making their forward strikes, but they were still able to catch prey using the backwards strike. The researchers thought the spiders were "hearing" their prey with the sensors on the tips of their legs. All spiders have these sensors, but scientists had previously thought they were only able to detect vibrations through surfaces, not sounds in the air.

To test how well the ogre-faced spiders could actually hear, the researchers conducted a two-part experiment.

First, they inserted electrodes into removed spider legs and into the brains of intact spiders. They put the spiders and the legs into a vibration-proof booth and played sounds from two meters (approximately 6.5 feet) away. The spiders and the legs responded to sounds from 100 hertz to 10,000 hertz.

Next, they played the five sounds that had triggered the biggest response to 25 spiders in the wild and 51 spiders in the lab. More than half the spiders did the "backward strike" move when they heard sounds that have a lower frequency similar to insect wing beats. When the higher frequency sounds were played, the spiders did not move. This suggests the higher frequencies may mimic the sounds of predators like birds.

University of Cincinnati spider behavioral ecologist George Uetz told Science that the results were a "surprise" that indicated science has much to learn about spiders as a whole. Because all spiders have these receptors on their legs, it is possible that all spiders can hear. This theory was first put forward by Walcott 60 years ago, but was dismissed at the time, according to the Cornell Chronicle. But studies of other spiders have turned up further evidence since. A 2016 study found that a kind of jumping spider can pick up sonic vibrations in the air.

"We don't know diddly about spiders," Uetz told Science. "They are much more complex than people ever thought they were."

Learning more provides scientists with an opportunity to study their sensory abilities in order to improve technology like bio-sensors, directional microphones and visual processing algorithms, Stafstrom told CNN.

Hoy agreed.

"The point is any understudied, underappreciated group has fascinating lives, even a yucky spider, and we can learn something from it," he told CNN.

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