Silent Spring inspires groundbreaking thesis

June 10, 2004, vol. 30, no. 4
By Roberta Staley



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In 1962, Rachel Carson published Silent Spring, the seminal book on the harmful effects of pollutants on the natural world.

Although Carson died two years later, her passion inspired others to study the ongoing chemical assault by man on nature.

Christy Morrissey, the dean of graduate studies medal winner in science, is an heir to Carson's legacy. Morrissey's PhD, focused on analysing levels of chemical pollutants in a bird called the American Dipper, has resurrected Carson's warnings.

Grey-feathered Dippers, found in the Fraser Valley along the Chilliwack River, are an indicator species, a barometer of the health of an ecosystem.

This region receives windswept emissions from Lower Mainland vehicles, as well as pollution from local industries such as pulp mills.

Airborne and industrial pollution such as PCBs, metals and organ-ochlorines enter the streams from rain and snow and work up the food chain.

Dippers ingest these pollutants by eating invertebrates such as mayflies and salmon fry, says Morrissey, who completed a bachelor of science at UBC.

Morrissey spent six months a year in the field, a luxury for any university researcher. She recorded Dipper behaviour, tracking migration pathways and analysing blood samples and feathers to determine the level of contamination. She found 165 nests and followed the growth of the fledglings, sending unhatched eggs to the laboratory.

Tests showed the egg contents contained significant concentrations of DDE, a metabolite of DDT that is linked to reproductive problems in humans and wildlife.

Although DDT has been banned for two decades, Morrissey says her findings indicate it is still in the environment.

The groundbreaking work has impressed the scientific community; Morrissey has published five times in such august tomes as the Journal of Applied Ecology and Canadian Journal of Zoology.

Morrissey is now busy with post-doctoral work, studying the effects of organic arsenic on mountain pine beetle predators, particularly woodpeckers.

The British Columbia government has been mum about the widespread use of arsenic - a known carcinogen - to control the pest, which has infested and destroyed thousands of hectares of lodge pole pine stands. “There is virtually no information on its toxicity to birds,” says Morrissey.

“This is a really important area of science,” she continues. “You can combine applied science with something you love, which is nature and the environment. Rachel Carson saw the threat that was there, and I see it, too.”

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