Petrillo ’12 Pioneers Urbanization Study of the Wissahickon Watershed

By schwartzsa | August 9, 2011

This summer Robert Petrillo ’12 is examining how urbanization affects stream salamanders in the Wissahickon Watershed, under the supervision of Dr. Christopher A. Binckley, Assistant Professor of Biology. In addition to using the study for his Senior Capstone project, Petrillo hopes to publish his results and teach environmental science in the future.

Using satellite photographs of Philadelphia’s Fairmount Park, Petrillo measures how much of the land surrounding streams has been urbanized—covered by impervious surfaces (houses, businesses, roads, etc.) that prevent the absorption of rainfall. In his pioneering study, the Biology major has identified 34 streams ranging from 10- to 90-percent urbanized.

He hypothesizes that salamander abundance and diversity decreases in more urbanized streams. To test his hypothesis, Petrillo collects salamanders from multiple sites at each stream, and then he calculates their quantity and mass to see if the data correlates with urbanization.

He catches the amphibians by hand, weighing and photographing them before returning them to water. In addition, he records changes in stream pH, temperature, conductivity, and dissolved oxygen and collects and measures samples of rocks, logs, leaves, and other cover-objects within a given stream and 1.5 meters up its banks.

The process can be exhausting. Luckily, Binckley does more than mentor—he helps his student collect samples. “It’s awesome,” Petrillo says of the experience of working with Binckley. “Going into this, I didn’t really know much about conducting my own research and collecting samples but he’s taught me everything. He’s an awesome guy.”

After graduation, Petrillo hopes to return to Arcadia for a Master of Arts in Environmental Education. “I want come back and keep a hand in my research for a little longer,” he says. “Then, hopefully another Biology major will want to take it over.”

“One of the very best things that Arcadia offers its students is the opportunity to conduct state-of-the-art research one-on-one with our gifted faculty,” said President Carl (Tobey) Oxholm III.

“Here, discovery and innovation are not just read about in books – they are experienced with the hands and a mentor. These experiences prepare our students well for graduate schools and careers and help to ensure that our country will have creative minds eager to take on new challenges. But these experiences also create informed citizens, as our students know firsthand how difficult true scientific inquiry is and are better able to evaluate and participate in public discourse about scientific issues that will have local, national and global significance in the coming decades.”