We contribute over half the water to the (Chesapeake) Bay and well over half the nitrogen and phosphorus, so the nutrients (that those who fish) care about are coming from us.

What does drainage from abandoned coal mines in central Pennsylvania have to do with nutrient problems in the Chesapeake Bay?

A lot, according to studies by Associate Professor of Biology Matthew McTammany '95 and his colleagues. The nutrients - nitrogen and phosphorus - that are depleting oxygen in the bay and killing off the fish, oysters and blue crabs that were once the heart of a vibrant fishery come largely from sewage, agricultural fertilizers and the burning fossil fuels. They are carried into the bay by the rivers that feed it. As the largest source of water in the Chesapeake Bay, the Susquehanna River also is its largest source of nutrients.

"We contribute over half the water to the bay and well over half the nitrogen and phosphorus, so the nutrients they care about are coming from us," McTammany says.

Just as the Chesapeake Bay is the product of its feeder rivers, the Susquehanna River is the product of its feeder streams. Throughout central Pennsylvania, the small creeks and brooks that flow through mountains, farmlands and towns all pick up nutrients and carry them downstream toward the river. How far the nutrients travel depends how healthy the stream is. "Ecosystems that are efficient at processing nutrients are very retentive of them," McTammany says. "They don't let them travel very far before they are using them again."

The thousands of miles of streams that are damaged by abandoned mines, however, do not process nitrogen, in particular, efficiently. Instead they send it downstream to the Susquehanna River and eventually to the Chesapeake Bay. That finding, by McTammany and colleagues from Bloomsburg University and the Stroud Water Research Center in Avondale, highlights an added value of remediating streams damaged by mine drainage: Remediated streams regain the ability to retain nitrogen.

The unexpected link between abandoned mines and nutrient loading hundreds of miles away illustrates a central theme in McTammany's research into aquatic ecosystems: "It all fits together," he says. "That's the great thing about water; it's the universal connector."

Students are exploring these connections and more in a new hands-on program. In Bucknell on the Susquehanna, McTammany and co-teachers Craig Kochel and Peter Wilshusen guide students through a full semester studying the cultural and natural history of the river basin, including excursions upstream to the headwaters in Cooperstown, N.Y., and downstream to the Chesapeake Bay.

McTammany is also studying the effects of the dramatic swings in oxygen levels that occur during drought years in shallow backwaters - exactly the habitats preferred by juvenile smallmouth bass. In collaboration with the Susquehanna River Heartland Coalition for Environmental Studies, he has also installed water-quality sensors in the north and west branches of the river. Every 15 minutes the sensors measure several variables and upload the data to a website. Having such a rich dataset leads to endless hypotheses about how the river functions.

"Rivers are complicated, but what makes them complicated also makes them wonderful," McTammany says. "There's a lot more work to do."

Posted Sept. 20, 2010