But Kidd also has some good news: Once you take the estrogen out of the system, given enough time, the fish return to their original abundance. By 2006, three years after the scientists ceased adding estrogen to the water, the fathead minnow began to repopulate the lake. This suggests that if treatment plants could remove such chemicals from municipal wastewaters before they enter the environment, affected ecosystems could rebound.
*Dilution Not the Solution*
Steven Bay at the Southern California Coastal Water Research Project in Costa Mesa, Calif., has seen evidence of altered hormone levels in marine fish. The hornyhead turbot, a common flatfish in the coastal waters of Southern California, hangs out on the seafloor where it can be exposed to a chemical cocktail discharged from nearby wastewater pipes. These chemicals range from industrial compounds to pharmaceuticals, some of which could contain substances that interfere with the fishs hormone system.
Bay found that up to 90 percent of the male hornyhead turbot tested at some locations had produced egg yolk proteins. They also had estrogen levels as high as females and low thyroid hormone and cortisol levels. Thyroid hormone manages growth, so development of the fish embryos could be impaired. And as cortisol is produced in response to stress, the low levels could actually mean the fish might be overstressed and worn out, leaving them vulnerable to disease. Most of these responses in the fish were widespread and not confined to the areas around the discharge pipes, so their precise cause and source remain a mystery.
|Contact: Matthew Wright|