HOOD CANAL, Washington (21 June 2003) -- With a low rumble, the crane lifted a cagelike contraption out of the depths of Hood Canal and lowered it, dripping, onto the deck of the R/V Thomas G. Thompson. A half-dozen volunteers swarmed around the device, withdrawing water samples from long metallic cylinders. Testing of the samples was soon under way in laboratories aboard the 274-foot research ship owned by the University of Washington. Stunning findings emerging from last weekend's cruise suggest that Hood Canal could be headed for another crash this fall, possibly worse than last year's. Last October, oxygen levels in the water dropped so low that bottom fish, struggling to breathe, swam to the surface where there was more oxygen in the water. Slow-moving sea cucumbers and octopuses protecting their broods suffocated and died. Shrimp became lethargic and many came down with a parasitic disease. For the first time in the history of Hood Canal, state officials canceled fishing for all but salmon. Now, local residents and concerned officials hope to launch a scientific inquiry into the problem, beginning with local volunteers working in concert with state and university researchers. The critical questions at hand: Why is Hood Canal killing its own sea life, and what role do humans play in the dynamic ecosystem? OXYGEN LEVELS Jan Newton, an oceanographer with the Washington Department of Ecology, has been tracking Hood Canal's oxygen readings for years. She has never seen it as bad as last fall. During past years, oxygen levels frequently got down to 5 milligrams per liter, which is considered stressful for fish. Below 2, the water is considered hypoxic, or injurious to sea life. Last year, in the southern portion of Hood Canal, levels got down to 0.3, creating a "dead zone" that kills most marine life. Bad times for sea life could lie ahead again this year, Newton said, because oxygen levels in some locations have already dropped to 1.5. Nothing like that was seen at the same time last year. In fact, the levels of oxygen at all depths and stations are lower than this time last year. The need for good information about Hood Canal is growing more critical if people hope to understand and reverse this dangerous trend, Newton said. Under the current program, researchers land a seaplane in Hood Canal each month to collect water samples. Twice a year, the Thompson journeys into the waterway as part of a scientific and educational program called PRISM, for Puget Sound Regional Synthesis Model. The cagelike contraption aboard the Thompson holds a variety of instruments that can take measurements at every depth. The device is nicknamed CTD, for conductivity, temperature and depth. The instruments aren't foolproof. To insure accuracy, the CTD allows for direct sampling of water with a circle of 24 open, stainless-steel tubes. Caps at the end of each tube are snapped shut remotely to take a water sample at any depth. The work requires a science crew of 20 to 25 aboard the Thompson, which operates around the clock. VOLUNTEER PROGRAM Even with all the expensive equipment, the current sampling program gathers only monthly information from 10 stations down the middle of Hood Canal. What happens between those sampling dates and in shallow waters is unknown. That's why a volunteer sampling program is being planned in Hood Canal and why Hood Canal resident Bob Hager joined the cruise last weekend. Hager, retired from the Boeing space program, is chairman of the Lower Hood Canal Watershed Implementation Committee. The committee was formed to battle bacterial pollution from septic systems and livestock waste, but now Hager finds himself caught up in the battle to save Hood Canal from oxygen deprivation. | | Volunteers lower "CTD" onto deck of R/V Thomas G. Thompson. Also on the weekend cruise was Dan Hannafious, technology director for the Hood Canal Salmon Enhancement Group. Hannafious will help set up a lab at the Hood Canal Wetlands Center in Belfair to analyze the water samples. Hager hopes to interest enough volunteers, including people with pleasure boats, to take weekly samples at various locations in Hood Canal. In the planning stage are perhaps five monitoring buoys that would sample the water continuously. PLANKTON AND HUMANS In summer, with long days of sunlight, plankton are busy gobbling up nutrients that have flowed into Hood Canal from natural and man-made sources. The plankton multiply quickly and sometimes create massive blooms in the water. As all those plankton die, they drop to the bottom, where decomposition consumes the available oxygen. In Hood Canal, more nutrients produce more plankton, resulting in more decomposition and less oxygen. Hager recently estimated that 500 tons of nitrogen are deposited each year in Hood Canal from sources that include lawn fertilizers, septic systems and runoff from farms, forests and lawns. What that means for Hood Canal is a tricky question. "If we limit the amount that goes in, we know it will help," Hager said, "but we don't know the extent to which it will help. If we cut the amount in half, will it stop the process, slow the process or reverse the process? "I think we're at the point where we really don't know the magnitude of what we are doing." What is really needed, he said, is a detailed mathematical model for Hood Canal. The three-dimensional model would show the effects of removing nutrients -- and the risk of adding more. The model would cost a lot of money, but it could lead to ideas for saving Hood Canal or determine if the waterway is destined to become a dead sea. THE FUTURE Low-oxygen "dead zones" have plagued the Gulf of Mexico and Chesapeake Bay for years. Last summer, the hypoxic area in the Gulf grew to record size, larger than the state of Massachusetts. Fish and shrimp try to escape the dead zone, which can't support life. Low-oxygen areas in Chesapeake Bay have been blamed for economic losses in the seafood industry. In both problem areas, strategies have evolved around reducing nutrient input, with agricultural sources a primary target. Getting ahead of the problem in Hood Canal might avoid the cascading effects of oxygen depletion, officials say. In Chesapeake Bay, for example, low-oxygen levels have resulted in the death of sea grasses -- critical habitat for blue crabs and other species. The decaying grasses then contribute to further loss of oxygen. Hood Canal suffers more than Puget Sound as a whole because of a complex set of factors, including poor mixing of deep waters, low flushing to the ocean and good growing conditions for algae. Seawater tends to flow into Hood Canal along the bottom and escape along the surface. Mid-level waters don't get mixed as well, resulting in greater oxygen depletion. "People need to know," Newton said, "that Hood Canal has unique properties that make it more sensitive than the main basin of Puget Sound." SOURCE - Seattle Times |
