“When your job is to grow larvae and you see that on the screen,” Jones said, “it’s extremely frustrating to see. If they weren’t dead already, they were dying. Light shined through them, revealing empty insides. He pointed out a few healthy ones, dark round discs scuttling around, propelled by hair-like cilia. Jones, who manages Taylor Shellfish Farms’ hatchery here on Dabob Bay, fiddled with a knob, bringing into focus a dozen or more 9-day-old oyster larvae. Tanks of seawater gurgled in the background. “It’s the perfect bacterial setup, and we get these explosive blooms along the coast.”Įdmund Jones removed a pinch of brown silt and smeared it across a glass slide. “It seems to be logical that the dead zone is playing a role,” said Ralph Elston, who runs a veterinary medical practice in Sequim, Wash., that offers advice to shellfish farmers. Researchers were not surprised to find this type of bacteria in seawater but were stunned that it had become so dominant over other microbes: It was nearly a pure concentration of this one bacteria, one that happens to be deadly to oyster larvae. And when brought to the surface with water welling up from the deep, it can switch survival strategies to flourish in warm, well-oxygenated waters. This bacterium thrives in oxygen-starved dead zones, feasting on decaying plant and animal matter littering the seafloor. Scientists note that Vibrio tubiashii has an advantage over other microscopic life in the sea. These low-oxygen waters correlate with stronger winds coming from a warming planet. The Vibrio blooms appear to be linked to warmer waters in estuaries and the oxygen-starved “dead zones” that have showed up this decade off the coast of Oregon and Washington, researchers said. It attacks them in their vulnerable, free-swimming larval stage before they settle to the seafloor, latch onto rocks or other oysters and grow thick shells. Science has identified the culprit, a strain of bacteria called Vibrio tubiashii, which is harmless to humans but fatal to baby oysters. I realized if I go out of business, I take a lot of people with me.” “We almost decided to close, and people panicked. The hatchery, she said, has been drowning in costs and failing to produce sufficient oyster larvae for West Coast shellfish farmers. “It’s pretty scary,” said Sue Cudd, owner of Whiskey Creek Shellfish Hatchery in Netarts, Ore. Then the microscopic culprit overran commercial hatcheries in Washington and Oregon, crippling production over the last couple of years and causing a shortage of oyster “seed” needed to replant tideland farms from Southern California to Canada. “All we saw was our larvae were dying,” said fisheries professor Chris Langdon, “and we couldn’t put our finger on why.” The outbreak first shut down an oyster brood stock program run by Oregon State University in Newport, Ore., in 2005.
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