Sunday, 12 August 2018

King’s College professor leads salamander study, red-back and lead-back salamanders,Pennsylvania, USA - via Herp Digest




KENT JACKSON, STAFF WRITER,JUNE 24, 2018, Citizen’s Voice
SALEM TWP. — As a professor and his students turned over wooden slabs, two salamanders squiggled for cover: red-backs and lead-backs.

Like twins, their names rhyme and they look alike, except for different-colored stripes down their spines.

Brian Mangan, a biology professor at King’s College, noticed difference.

Lead-backed salamanders absorb two times as much mercury as red-backs.

Perhaps their diets or behaviors differ.

Maybe they lose their tails to predators at different rates.
Shedding a tail also sheds mercury, Mangan figures.
Mercury factored into much of the research that Mangan did along the Susquehanna River before he followed salamanders.

Although mercury occurs naturally, it also enters the environment through human activities such as burning coal. Mercury accumulates in the body and poses larger risks to women who might become pregnant, nursing mothers and young children, whose developing nervous systems suffer from exposure.

For years, the Pennsylvania Fish and Boat Commission told people to eat no more than two meals a month of fish caught in the river in Northeast Pennsylvania because of mercury. The advisory intrigued Mangan, leading him to study how mercury moves through the river’s ecosystem in crayfish, bass and spiders.

When studying salamanders near the river, Mangan grew curious about a research method in which scientists place pieces of wood, metal or ceramic tile on the ground to attract salamanders.

Do the covers make a habitat better or worse for salamanders, which like wet, cool areas?

The covers might repel rain like roofs or promote condensation, Mangan thought while wondering if covered soil stays cool compared with surrounding ground.

To find out, he arrayed squares of plywood in grids at three areas where salamanders live at the Riverlands natural area owned by Talen Energy.

And he enlisted help.

Two of his students, Neil Mras and Kyle Swetz, lift up each of the 324 plywood squares three times a week. They insert a probe into the soil that measures temperature and moisture content beneath the squares and of uncovered soil nearby.

Calling out moisture content first, Swetz said, “21.7; 20.7” as Mras wrote the figures in a notebook.

“They’re learning the importance of replication,” said Mangan, explaining that too few data points lead to invalid conclusions, while too many exhaust time and money.

Since starting the environmental program at King’s 17 years ago, Mangan obtained grants of $900,000 for research. This summer, the Degenstein Foundation gave $10,000 for the salamander study.

The grant pays for the soil probe and also the salaries of Swetz and Mras.

While collecting data, Mras, a senior from Hunlock Creek, and Swetz, a junior from Hazleton, will learn more about salamanders and the plots they are studying. Because salamanders like mature forests, the students will measure tree diameters.

Gazing into a calibrated mirror shaped like a bowl, Swetz and Mras will compute openings in the tree canopy to ascertain how much rain might reach soil, which they will sample for clay and sand content to rate how soil retains rain.

Using statistics, the students will note variations and look for patterns in their data before sharing findings with other scientists and students at a symposium about the Susquehanna River this fall.

For now, their work can be monotonous.

Mangan tells them to keep alert for sights that don’t make sense.

“This is not biological factory work. You’ve got to look at it as exploration and adventure,” he said as they walked along paths from which they could watch the river and an old canal that is turning to marsh. “You may see something no one has ever seen before.”

Mangan once saw a structure unknown to scientists on the shell of a crayfish. It turned out to be a home built by an aquatic fly.

Curiosity about what he sees continues to give him study ideas.

At a boat launch in Halifax, Dauphin County, he watched hundreds of crayfish scatter, the largest horde he had ever seen.

They were rusty crayfish, probably brought to the Susquehanna River from the Ohio River Basin in the bait buckets of anglers in the mid-1970s. In a study for which he designed traps, Mangan found that the rustys displaced Allegheny crayfish along much of the Susquehanna between Harrisburg and the New York border.

Another creature, the spined micrathena spider, “appears magically in July” so he sought to learn its tricks. While studying the life cycle of the spider, Mangan noticed a difference in micrathenas’ mercury levels based on their distance from a coal-fired electricity plant.

Salamanders in this summer’s study have been scarce.
In the first weeks, the researchers didn’t see any because the plywood was too fresh. Just to get a look at their quarry, they overturned more weathered discs in an older study plot.

As the days warm, salamanders may worm their way underground to stay cool and emerge at night. Their skin has to stay moist because they breathe through it.
Scientific literature says red-backed and lead-backed salamanders, which are morphs of the same species, will climb vegetation on hot summer nights and forage.
“I’d like to see that,” Mangan said.

The salamanders eat ticks, ants, spiders and snow fleas. Of course, other species eat them.

After noting that some of the plywood squares had been overturned at night, Mangan posted game cameras.

Raccoons looking for snacks proved to be the culprits.

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