Bacteria Taking Over Portions of Hood Canal
Environment | Biologists haven't finished mapping the extent of the fluffy white material growing where oxygen is low.
By ChristopherDunagan,
cdunagan@kitsapsun.com
September 22, 2006
Belfair
Some underwater areas of Hood Canal have become an alien landscape, devoid of sea life and inhabited by a fluffy white bacteria that grows in extremely low-oxygen conditions.
The bacteria, which were growing below 50 feet of water near Twanoh State Park, were discovered by divers for the Skokomish Tribe, according to a research report released Thursday. The divers, searching for other invasive species known as tunicates, found the cottony bacteria growing in mats up to 3.5 feet thick.
Dave Herrera, fisheries manager for the Skokomish Tribe, said it appears that conditions in southern Hood Canal are worsening.
"This is certainly within the area where the lowest levels of oxygen have been seen over the past two years," Herrera said, "but to see what was found out there was pretty shocking to us."
An inspection of eight random areas between Twanoh State Park on the south shore and Belfair State Park on the north shore found:
Areas covered entirely by the bacteria with no sea life present.
Areas without bacteria and live animals present.
Patchy areas with just ajelly-like substrate that contained dead salmon fry, jellyfish and crabs.
All areas below 50 feet contained the bacterial mats, and they appeared to increase with depth, though the divers did not descend below 68 feet, according to the report.
"Our assessment was just three days," Herrera said. "We don’t know the extent (of the bacteria) to the west. Even greater, we’d like to start focusing attention on marine resources that live there — or lived there. We’d like to see a lot more work done to assess what is happening to clams, oysters, geoduck, crab, shrimp ..."
While the oceanographic studies of currents, nitrogen releases and plankton growth are important, he said, additional biological assessments are needed. The appearance of the bacterial mats might even be used as an indicator of low-oxygen conditions, the report suggests.
"Our treaty resources are disappearing, or appear to be disappearing," Herrera said. "We need to look at things a lot more closely."
Oceanographer Jan Newton, science director for the Hood Canal Dissolved Oxygen Program, said such bacteria are associated with low-oxygen conditions.
"We know that area has had low oxygen for a long, long time," Newton said. "It is not surprising that it (the bacterial growth) is there."
She agreed that more biological assessments should be funded.
During the survey, divers observed dead fish at several places where the mats were present.
"No animals at these sites appeared to be normal and unstressed," states the report. "Dead crabs, jellyfish and tunicates were found at these sites. (At three locations), a total of 118 dead Dungeness crabs were recorded. Most of these were intact and buried in the substrate. They were black in color and crumbled when handled at some locations."
Samples of the bacteria were collected for laboratory analysis, and the Environmental Protection Agency is expected to send divers to the area in coming days. Biologists speculate that the bacteria are one or more species of Beggiatoa, an anaerobic bacteria that grows in extremely low-oxygen conditions in contact with sediments, such as on the bottom of a bay.
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- Janna
