Wednesday, December 19, 2007

Zebra Mussels and the Columbian Exchange

Steve LeVine has a good piece on the invasion of zebra mussels into North American waterways. This invasive species from central Asia is ripping through our river systems, clogging pipes, eating phytoplankton, and starving out other organisms.

We are still dealing with the Columbian Exchange. As named by the great historian Alfred Crosby, the Columbian Exchange is the exchange of biota and diseases between the Old World and New World. This is one of the most important events in world history. I argue that in the past 500 years, only the Industrial Revolution is more important. The Americas have always had the worst of this exchange. Time after time over the past 515 years, Old World invaders have ravaged American environments--smallpox, chestnut blight, pneumonia and other respiratory illnesses, rats, cockroaches, pigeons, zebra mussels. True, some Old World foods came over that we like--wheat, wine, etc. So did domesticated animals such as horses, cows, and sheep. But the Old World received many more benefits--corn, tomatoes, chile, chocolate, etc. Moreover, to my knowledge, the only destructive organism to ravage the Old World was syphilis. I highly recommend Crosby's chapter on this.

Like many invasive species, the zebra mussel first came to the United States from shipping. They were first discovered in the U.S. in 1988 and have spread to 23 states since. Even if you don't care about the environment, they are bad because they clog up power plants and other industrial operations on waterfronts, potentially endangering those companies and costing millions of dollars to eliminate, only to know they will come back at the blink of an eye.

Even today, the American environment suffers from continued invasions. Zebra mussels are only one of the latest examples. AIDS, kudzu, various pathogens attacking eastern trees--all are serious threats to our environment and even to our health. This is a major impact of globalization, a process that really began well before 1492. We continue to struggle against the Columbian Exchange today. Biodiversity is plummeting, particularly on islands and in the Americas. Our increasingly homogenized environment is one of the most depressing things about the modern world.