Not quite right as rainwater
by Eric Sorensen | © Washington State University
Jen McIntyre is something of a rainwater connoisseur, but you wouldn’t want to drink from her collection. Her preferred source is a drainpipe that runs from State Route 520 to a parking lot in Seattle’s Montlake neighborhood.
Tens of thousands of cars and scores of buses pass by every day, dropping bits of tire rubber, brake dust, exhaust, and the occasional cigarette butt. In winter, passing showers might rinse off the road surface every few days or hours. In summer, a month might go by between rains, giving McIntyre a particularly potent stormwater cocktail, like the one she harvested last August.
Freshly bottled, it’s brown and nearly opaque. If she freezes and thaws it, it clears up, with little pieces settling out.
“These are maybe bits of leaves, bits of rubber,” she says while working one rainy afternoon with an October 20, 2011, vintage. “Sometimes there’s sand, silt, and mud. Sometimes there’s bugs, little baby spiders.”
But it’s the bouquet that’s most fetching.
“Sometimes it smells poopy,” she says. “The really toxic one, the one I got this summer, smelled like an ashtray.”
She soon realized this makes sense. Cigarette butts are the world’s most common form of litter, according to research she unearthed, and just one butt is enough to kill half the fish in a liter of water. McIntyre’s own work has focused on the effect of copper on salmon, but there’s a bigger picture here and no matter how you look at it, it’s not pretty.
Discussions of endangered salmon have often centered on the Four H’s of hydropower, hatcheries, harvesting, and habitat. In looking at the fish’s urbanized environs, McIntyre and other researchers like to note that a salmon’s habitat is both physical and chemical.
Simply put, cities, suburbs and their attendant roadways, rooftops, and parking lots are not the forests that salmon have swum through and adapted to over the ages. Scientists like McIntyre are now sorting out the implications as part of a broad effort by the WSU Puyallup Research and Extension Center.
“The major thrust of this center right now is addressing water quality for the future and we’re doing it on many different levels,” says John Stark, center director and environmental toxicologist.
The center’s Low Impact Development Program has recently finished installing a parking lot of permeable asphalt and concrete. The pavement surfaces and various catchments will keep rainwater from washing into the nearby Clarks Creek while helping answer the question of whether the water is treated by the pavement and underlying gravel.
“This fundamentally changes how we are going to manage stormwater,” says Curtis Hinman, extension professor and the program’s science lead.
Nearby, rain gardens and mesocosms— plastic tanks filled with different soil mixes—take advantage of the soil’s ability to retain and treat water. Researchers are using them to study which soil blends are better at removing pollutants.
Two 3,000-gallon cisterns catch runoff from 70,000 square feet of roofing and pavement, giving researchers a stormwater source that they can amend with, say, street dirt from Seattle, to test on different plants and soils.
In an indoor lab, McIntyre, a postdoctoral researcher and aquatic ecotoxicologist, tests water fleas, freshwater invertebrates that act as proxies for salmon food, to see how they are affected by stormwater. If the water is a week old, it’s fine, possibly because hydrocarbons have evaporated or been consumed by microbes. But whole populations of water fleas were wiped out by a fresh batch of her most potent August stew.
Her Seattle work is a collaboration of the Puyallup center and the National Oceanic and Atmospheric Administration’s Northwest Fisheries Science Center, where McIntyre first started working as a University of Washington doctoral student. There she found that copper, an element in brake pads, had dramatic effects on salmon.
At high levels, copper can kill a fish outright. But McIntyre is also intrigued by indirect deaths, which can stem from the demise of a creature’s food source, or ecological death, in which a pollutant can affect an animal’s reproduction or so disrupt its normal functioning that it dies.
Copper is a neurotoxin, and McIntyre looked at how it disrupts the sensitive neurons salmon use to smell. This is critical to a fish’s feeding, migration, socialization, and reproduction, as well as defense, McIntyre’s main focus.
“They can smell a predator,” she says.
A key compound in a fish’s defense is Schreckstoff. German for “scary stuff,” it is a chemical produced when a fish is physically damaged, alerting nearby fish to a possible predator attack.
McIntyre has done experiments comparing normal juvenile salmon with salmon exposed to copper. The normal salmon will freeze in the presence of Schreckstoff, effectively hiding from motion-sensitive cutthroat trout, a common predator.
Salmon exposed to copper, says McIntyre, “just keep swimming around—‘Everything’s great,’ and chomp!”
The work was part of research that led to state legislation phasing out the use of copper in brake pads.
In the early stages of her new work, McIntyre is looking at the effects of stormwater on zebrafish, whose rapid embryonic development and transparent body make them “a pretty popular aquatic lab rat.” Scientifically, they’re giving McIntyre the revelations researchers live for; ecologically, they’re a horror show.
She’s seen embryos with small eyes, jaw deformities, nonexistent swim bladders, and hearts that are “just wrong,” with swelling around them or poorly developed chambers. “The heart’s beating, but it’s just not doing its job,” she says. “Often toxicology is a really depressing field to work in.”
McIntyre will next start working with coho salmon, whose long tenure in freshwater makes them sentinels whose health speaks well for the food web, the quality of its streams, and the stormwater that does or doesn’t run into them.
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