A simple life
Interesting article in
today's Seattle Times about an unwanted hitch-hiker in Puget Sound:
The blob that's invading the Sound
Like knights heading into battle, two dozen people in rubber-coated diving suits and 40-pound air tanks clanked down the gravel beach.
They each clutched weapons: windshield ice scrapers, barbecue tongs, a spatula nabbed from the kitchen.
Their hated enemy lay beneath Hood Canal's frigid waters, a creature that had scorned a previous assault, expanding its territory at a ferocious rate.
It's a 6-inch-long blob of goo called a tunicate, a siphon-feeding animal much like a clam without a shell.
Around Puget Sound, the appearance of the tenacious, fast-spreading breed of sea creatures, also called sea squirts, is alarming divers, biologists and government officials.
While their impact on the Sound's troubled ecosystem is unknown, some of the same species have wreaked havoc elsewhere, coating miles of underwater habitat in slime, smothering farmed shellfish, displacing native species and proving extraordinarily hard to fight off. One species found here has already damaged shellfish farms in eastern Canada.
Their presence may be further evidence that the Sound is under stress, making it particularly vulnerable to invaders, like a bulldozed piece of land overrun by blackberries and dandelions.
Invasion spotted
Not every tunicate causes trouble. The Sound has long been home to a variety of the siphon-feeding creatures, many resembling delicate little tubes of blown glass.
But in 1998, scientists saw the first sign of trouble. They discovered two non-native varieties of tunicate at marinas. In 2004, a third kind showed up, at a popular diving spot near Edmonds.
It's not known how they got here. Two species originally come from Asia. The origin of the other is unclear. Scientists think ocean-going ships might have brought some species here. One species might have come from industrial shellfish operations using contaminated equipment or shellfish.
These invasive tunicates have cropped up at more than 20 places throughout the Puget Sound and Hood Canal. In some spots there are just a handful. But in the southern reaches of Hood Canal, the bottom is coated with a forest of tiny, pale white tubes.
"It was like on an alien planet. This stuff was just everywhere. It was the creepiest thing I'd ever seen," said Janna Nichols, a diver who leads volunteer efforts to destroy the tunicates.
An excellent page on the one infesting the sound (Ciona savignyi) is here at the University of Washington:
Ciona savignyi
Science News also has some info:
Squirt Alert
I used to work for these people doing IT support:
The Glosten Associates and while I was there, they were working on a solution to the Shipboard Ballast Water problem. A ship is designed to carry a specific load and may become unstable if the load is not there. A tanker coming into port to deliver its cargo will pump saltwater into its tanks to compensate for the weight lost. When the tanker goes back to its home port, that water is pumped overboard when new cargo is taken on. The refineries in Puget Sound (as well as those in the Gulf States) see a lot of foreign ballast water and are suffering from alien invasions (non X-Files variety). Glosten's idea was to have a computer system monitoring the tanks and the pumps and at some point in mid-voyage, flush each tank and refill it with mid-ocean seawater. In the mid-ocean, invasive species like the Zebra Mussel and the tunicates will simply sink to the lightless abyss and die. At the same time, there are no surface species that can cause problems in port waters.
Talk about Win/Win. This system would operate as a sealed unit with a tamper-proof database; it would tie into the ships systems so the Captain could just initiate the process and the system would log the data and location as the tanks were flushed.
Posted by DaveH at February 20, 2007 8:20 PM