Pollution lower, risks remain for marine life
Last week, the state Department of Ecology released a report that showed oil pollution in Puget Sound was a fraction of what some environmental regulators had suggested. But experts suspect oil pollution in the Sound still reaches at least 710,000 pounds a year. And recent science shows petroleum byproducts and other contaminants found in runoff are probably monkeying with marine creatures in strange and troubling ways.
Seattle Times environment reporter
It can happen almost immediately.
Copper dust from car brakes gets flushed into a stream by storms. Inside half an hour, the ability of nearby baby salmon to interpret smells can get thrown out of whack. When a predator approaches, the fish don't flee, increasing the odds they'll be gobbled up.
This potentially deadly change in fish behavior can happen at extremely low levels of pollution, the same levels washing into Puget Sound during heavy rain. It's one of the many ways stormwater runoff still presents trouble for Puget Sound.
"You don't have to have dead fish for there to be impacts on aquatic life," said David Baldwin, a research biologist with NOAA's Northwest Fisheries Science Center.
The state Department of Ecology this month released a report that showed oil pollution in Puget Sound was a fraction of what some environmental regulators had suggested. Instead of an Exxon Valdez-size amount of oil every two years as some claimed, the petroleum flushed into the water from roads and parking lots appears, in fact, to be dozens of times lower.
But experts suspect oil pollution in the Sound still reaches at least 710,000 pounds a year. And recent science shows petroleum byproducts and other contaminants found in runoff, including copper, may well be monkeying with marine creatures in strange and troubling ways.
While petroleum pollution is less than once thought, "polluted stormwater runoff is still the leading pollution threat to Puget Sound," said Rob Duff, a program manager with the Ecology Department.
In Washington, pollution reaches the Sound in several ways, either through normal runoff as streams and rivers feed the marine world, or in stormwater, as heavy rains rush across homes and gardens and driveways and sweep pollution into the Sound. Air pollution, too, gets deposited, either directly or as runoff after it's fallen onto the landscape.
With 83 percent of the land that drains into Puget Sound still forested, perhaps it's not surprising that most pollution comes from cities and suburbs. More surprising is what's in it — and what it can do.
Copper, for example, may be among the most problematic. While common sources — dust from vehicle brake pads and some paint used on boat hulls — are being phased out, up to 140,000 pounds of copper still gets into the Sound each year. And even minute doses can impair fish neurons enough for scientists in the lab to measure.
It blocks the transmission of odors, which play a key role in helping salmon navigate their way back to native streams. It can even impair the way fish sense how water moves across their bodies, a sensation that helps them detect oncoming threats.
"As another fish approaches, it pushes water in front of it, like a bow wave," Baldwin said. "Fish can feel that change in the water when predators advance."
The flame retardants known as polybrominated diphenyl ethers (PBDEs), found in everything from couch cushions to computers, have the potential to weaken an animal's immune system and show up in high levels in Puget Sound chinook, the preferred food of southern resident killer whales.
And while petroleum pollution in Puget Sound is far less than first thought, it almost certainly contributes to another problem: contamination by polycyclic aromatic hydrocarbons (PAHs).
PAHs are a suite of chemicals formed by incomplete burning. They come from the exhaust released through vehicle tailpipes, oil spills and some sealants placed on roadways, but also from creosote-soaked pilings, coal, soot and the smoke from wood-burning fires and volcanoes.
PAH concentrations in mussels in Puget Sound already are among the highest in the country, and unlike some other contaminants, "oil-derived PAHs are toxic at very, very, very low concentrations," said John Incardona, a marine toxicologist with NOAA's Northwest Fisheries Science Center in Seattle.
At high levels, PAHs can cause lesions in sea urchins. At medium levels, they've been known to hamper the immune system of birds and shellfish. And toxicity can increase when the chemicals are exposed to sunlight, making marine life in shallow water particularly susceptible.
But even in small doses, PAHs are drawn like magnets to fish embryos, and the hydrocarbons that researchers worry about most are cardiac poisons — they disrupt the ability of hearts to pump properly.
"If it happens in an adult, they don't feel right, but they don't die," said Incardona. "But in a developing fish embryo, the heart won't get built properly."
Incardona and others started studying PAHs in the aftermath of the 1989 Exxon Valdez spill and another major spill in Spain in 2004.
They learned that zebrafish, exposed at the larval stage, grew up with odd-shaped hearts that couldn't work hard enough for the fish to swim at normal speeds.
The results have been repeated over and over, with minnows, rainbow trout, Pacific herring and pink salmon.
In fact, even when exposed to tiny amounts of PAHs, migrating pink salmon grew up and went out to sea, but 40 percent fewer fish came back.
Craig Welch: 206-464-2093 or firstname.lastname@example.org
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