Researchers are searching the ocean forDeadZones?areas with extremely low levels of oxygen that cannotsustain life. Last summer, a huge Dead Zone settled in onthe coast of Oregon, causing fish and crustaceans to die. Itdisappeared in the fall, but now it's back. OceanologistJack Barth says, "What I think we are seeing is a tipping ofthe balance of the ecosystem. We don't fully understand whatthe cause of that is."
Jeff Barnard writes that There are more than 30 man-man DeadZones, including Hood Canal in Puget Sound, the MississippiRiver delta and Chesapeake Bay. These are places wherenitrogen fertilizer from farm fields has washed into thewater, causing excess growth of tiny plants calledphytoplankton. When they die, the bacteria that decomposethem use up all the oxygen in the water, meaning fish, crabsand other marine life suffocate.
Naturally-caused Dead Zones in open water, like the one offOregon, are rare and less well understood. Others have beenfound off the coasts of Peru and South Africa. Marinebiologist Jane Lubchenco says, "[Oregon?s Dead Zone] mightbe a window into possibly important larger scale changes inthe Pacific."
"Because we think it is potentially a long-term change, tobe absolutely certain we need many years of observations,"Barth says. "We are still at the fundamental research level,but the impacts could be quite large."
When we probe the mysteries of the past, we find there'smoreto learn than conventional history books tell us.
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