In it for the Long Term: Tracking Salamanders Over Time

Staggered several meters apart, pairs of students hunting for tiny red-backed salamanders pulled up rotting logs and overturned stones in the forest at the Schiller Coastal Studies Center. When they spotted one — sometimes no bigger than a thumb nail — they measured, weighed, and sexed it, and also checked for any deformities.

The students, who are in the biology class Biodiversity and Conservation Science, were collecting data for a long-term salamander study created by Biology Lab Instructor Jaret Reblin. Reblin began the ongoing study at the Coastal Studies Center in 2003. Since then, ecology classes have visited, every year or so, the same exact spots along two long transect lines to look for salamanders — looking under both natural covers (logs and rocks) and also under artificial cover boards (slate and wood) placed along the lines years before.

This ongoing survey helps Biology and Environmental Studies Lab Instructor Shana Stewart Deeds keep track of whether the red-backed salamander population at the Coastal Studies Center remains healthy. It also teaches students the methods of long-term ecological research.

Amphibians in particular are valuable to keep tabs on over time because they are an indicator species, meaning they are often the first ones to feel the effects of pollution or climate change.

This year Deeds and her students found that the salamanders seem to have been affected by Maine’s recent drought. “In 2017, this year, our population numbers are lower than any other year that we have surveyed,” Deeds said. “And the most likely [hypothesis] is probably because it is so dry.” Maine’s red-backed salamanders are unusual here because they do not require an aquatic environment to breed like other amphibians. When the soil dries out, they are more difficult to find on the forest surface because they burrow more deeply into the earth, where it is moist, to survive and breed.

After the students collected data in the field, they returned to the lab and used statistical analysis to see if they could detect significant patterns in the data from year to year. “We can ask questions if, over the years, salamander populations are fluctuating, and then think about why,” Deeds said, weighing possible factors such as habitat variation, cover types (artificial versus natural), rainfall amount, and temperature change.

The salamander study is not the only long-term study being pursued by Bowdoin faculty and students. The Bowdoin Marine Science Semester is also committed to documenting changes in the algae and invertebrates living in inter-tidal zones along Maine’s coast. Each year they survey sites on Kent Island, Hurricane Island, and at the Schiller Coastal Studies Center. They are also tracking the benthic community in the Gulf of California. Assistant Professor of Biology Sarah Kingston has been following how well the shells of Gulf of Maine snails calcify, as they are a sentinel species for oceans and human health.

Assistant Professor of Biology Vlad Dohouvnikoff has been studying long-term plots of aspen to better understand their epigenetics. And additionally on Kent Island, where Bowdoin has had a scientific field station for 82 years, faculty and students have been monitoring several bird populations — Leach’s storm petrels (a study begun by Chuck Huntington), Savannah sparrows (started by Nat Wheelwright), and tree swallows. Another long study, originally set up by Bob Cunningham, has been following the fluctuations of fog.

Watch the video below to learn more about the Bowdoin Marine Science Semester’s long-term study of inter-tidal zones.

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