Fishing for Clues


Lynn Hannum spent her childhood in Monmouth, Maine, halfway between the Androscoggin and the Kennebec rivers. More than anything else about those two historic waterways, she remembers the stench. "Water Street in Augusta was terrible," she said. "You could barely stand to breathe."

By Stephen Collins '74
Photography by Fred Field

Assistant Professor Lynn Hannum at work in her lab at Colby. Some of her studies focus on the immune systems of fish in Maine rivers.
Photo by Fred Field
As an undergraduate at Bates she spent four years by the Androscoggin in Lewiston in the 1980s. As a Clare Booth Luce Assistant Professor of Biology at Colby since 2001, her office overlooks the Kennebec valley. Now she's immersed, figuratively, in both waterways.

Hannum earned a Ph.D. in immunobiology from Yale and, in addition to her work on circadian rhythms in immune systems, she has supervised studies of the immune systems of fish from both rivers since returning to Maine.

She and her stu—dent research assistants wait at a boat landing as anglers bring in bass and white suckers. They slice open the fish, not to clean them for eating but to collect their anterior kidneys for analysis. While the fish seem generally healthy, Hannum says the results of research show differences in one measure of immune-system function between fish taken above and below mill discharge.

Why? Scientists don't know, nor is there any hard evidence that the change is caused by chemical pollution, Hannum said. But the testing method could prove a useful tool in studying fish populations.

The Androscoggin and Kennebec have a special place in the history of river restoration. Edmund Muskie, the author of the federal Clean Water Act when he was in the U.S. Senate, grew up on the Androscoggin in Rumford and Lewiston (as a student at Bates), and later worked along the Kennebec as a lawyer in Waterville and as Maine's governor in Augusta.

Yet despite decades of efforts to clean up the Androscoggin, which arguably inspired the Clean Water Act, parts of it still have not achieved Class C status, the lowest classification for rivers in Maine.

Barry Mower, a fisheries biologist who works for the Bureau of Land and Water Management in Maine's Department of Environmental Protection (DEP), studies fish from above and below pulp mill discharges to see how the discharges may affect their health, but he was interested in "looking at more subtle effects than just survival," he said.

Testing fish

Comparing cells from small mouth bass caught below and above mills, "there"s a detectable difference in their immune systems.— Downstream fish have greater numbers of phagocytic white cells, but they are not as effective at fighting pathogens as cells from fish above the mills" water.
40%# "We had a need that we couldn't fill," he said, indicating that studying immune systems, growth rates, reproduction, and blood steroids are more specific ways of evaluating the effects of pollutants on fish. So he approached Hannum about immunology studies and offered a research grant from the Surface Water Ambient Toxics monitoring program.

After collecting the kidneys of fish from above and below paper mills, Hannum's students return to the lab to examine phagocytes, basic immune cells in animals. More specifically, they evaluate these cells' capacity for respiratory burst, a measure of their ability to bind with, engulf, and destroy harmful bacteria or toxins.

Comparing cells from smallmouth bass caught below and above mills, "there's a detectable difference in their immune systems," she said. Downstream fish have greater numbers of phagocytic white cells, but they are not as effective at fighting pathogens and infections as cells from fish above the mills' water.

Last year Patrick Slipp '05 published a biology honors thesis, "A Study of Innate Immune Function in Fish of the Androscoggin and Kennebec Rivers," characterizing work that Hannum supervised. Beyond the finding that immune systems below mill discharges are compromised, he concluded that not all species are equal as bioindicators of pollution stress, since the bass showed more dramatic differences than white suckers.

To further test the effect of mill-discharged water on immune response in fish, Slipp set up an experiment with a favorite laboratory specimen, the zebrafish or zebra danio, familiar in pet shops and home aquaria. Back in the lab he tried raising separate populations of zebrafish in water collected above and below mill discharges, conducting similar phagocyte assays on those fish. Given other difficulties in maintaining laboratory populations of the fish, results were inconclusive, he said.

Mower called the research conducted at Colby "very valuable" and "very well done." Most often, Mower's research grants pay for graduate students and DEP staff to run experiments, he said, but he has found that students from Colby, Bowdoin, and Bates, supervised by professors with Ph.D.s, are an excellent resource.

On his end, Slipp says the skills he learned in Hannum's lab have served him well. He works as a research technician at the Brigham and Women's Hospital's Division of Sleep Medicine in Cambridge, Mass., and hopes to attend medical school next year, he said.

The process he learned at Colby"familiarizing himself with literature on the topic, organizing experiments, and working in a research group"carried over to his work at Brigham and Women's. Hannum was a great mentor, he said, in part because of the responsibilities she gave him. "She gave me the freedom to do the research, decide on my own assay, and let me go out and collect most of the fish myself," he said.

While it's tempting to say that everyone wins except the fish, in the long run even bass and white suckers should benefit.
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