Editorial: Lakes in Crisis

As Scott Fields points out in his Focus article (Fields 2005), the Great Lakes are one of the most important water resources on Earth. Together the five lakes contain around 20% of the surface freshwater on the planet. The Great Lakes basin is home to close to 40 million people in the United States and Canada, and it is no accident that some of the largest and most heavily industrialized cities in North America are located there. During the industrial expansion the lakes provided a ready transportation system for delivering raw materials to factories and products to markets. They also provided a seemingly endless supply of water for industrial processes and acted as a convenient sewer for industrial waste. Ironically the same lakes that have been so heavily used and abused by industry support the largest freshwater fishery in the world, and both commercial and sport fishing are critical to the economy of the region. Over the last century the once pristine waters of the five lakes— Superior, Michigan, Huron, Erie, and Ontario—have become contaminated with a virtual soup of toxic chemicals. Most worrisome among these are chlorinated organic compounds that persist for long periods of time in the sediment of the lakes, enter the food chain, and bioaccumulate as they move from phytoplankton to zooplankton, to forage fish, and finally to predatory fish such as lake trout and salmon. Chief among these are DDE (dichlorodiphenyldichloroethylene), a breakdown product of the once widely used herbicide DDT (dichlorodiphenyltrichloroethane), and polychlorinated biphenyls (PCBs), once used as dielectric fluids in capacitors and transformers. Decades of research has revealed that these endocrine-disrupting chemicals can cause a host of health problems in wildlife and humans. The good news is that concentrations of PCBs and DDE in Great Lakes fish peaked in the 1970s and are declining. The bad news is that, because of their extreme stability, these chemicals will continue to be present in fish at levels that could represent a health risk for decades to come. Despite our experiences with DDE and PCBs, we seem destined to repeat our earlier mistakes. Recently, a new class of contami-nants—the polybrominated diphenyl ethers (PBDEs)—has exploded onto the scene. PBDEs, which are chemically similar to PCBs, are used as flame retardants in a myriad of products. Over the last 10–15 years the concentrations of PBDEs in Great Lakes fish have been increasing exponentially, and this trend shows no …