Fishermen off the shores of Oregon report that more amounts of dead rockfish, crabs and other bottom fish have been appearing in their nets and along the coast line.
There are an estimated 150 dead zones hugging coastal areas around the world. Some scientists say that there could be more than 4 hundred dead zones along 95 thousand miles of global coast line.
“This is the first time we have seen the dead zone expand,” said Jane Lubchenco, a marine biologist at Oregon State University in Corvallis.
Dead zones occur when agricultural fertilizers rich in nitrogen and phosphorus seep into the water supply and eventually find their way into the world’s oceans.
The chemicals provide nutrients to off shore microscopic algae. The algae grows and then slowly sinks and dies. As it decomposes in the sea depths it consumes the surrounding oxygen depriving other sea organisms of a life supporting habitat. The ocean area becomes a dead zone.
The earth’s largest dead zone is in the Baltic Sea. The largest zone in the United States is in the Gulf of Mexico, centered around the Mississippi delta. The oxygen starved sea area in the Gulf is approximately 85 hundred square miles and growing.
“Dead zones are not local problems,” said Dr. Robert Diaz, a marine biologist at the Virginia Institute of Marine Science. “They are occurring around the globe and have negative consequences in all locations. The surprising thing is that many of these zones are caused by the same set of processes and factors. It all links back to us, and what humans are doing.”
Entire species have been threatened. Dr. Diaz identifies bottom feeders such as some species of shrimp, clams and sea worms as being the most vulnerable.
As the dead zone algae sucks up the oxygen the surrounding marine life searches for the surface to survive. This stresses them and makes them more visible to predators.
“The conclusion is inescapable that dead zones are now a key stressor in coastal waters,” said Ms. Lubchenco.
She added that the problem might be solvable.
“The evidence suggests that if the spigot of nutrients can be turned off, coastal systems can recover,” she said. “Doing it can be accomplished by using fertilizers more efficiently, preventing human and animal sewage from entering rivers.”
Dr. Diaz suggests that the rise of small scale organic farming is helping stem the tide of fertilizer run off. The organic farming contribution to solving the dead zone problem is small when compared to the contributions in run off water from large scale industrial agricultural businesses.
“The problem is so big now,” said Dr. Diaz. “Governments have to figure out a way to keep the nitrogen in the soil and make crops green, not the sea.”