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.
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