These changes also can be triggered in the lab by adding androgens to the young eels' water. Presumably, Davis says, bacterial production of andro and related pollutants in the waterways foster the early maturation. Pulp-mill residues may be a concern in other countries, as well. One site produced 55 percent males, the other 58 percent. In 1999, a brief plant shutdown occurred.
Androgens can trigger devastating changes in another hormone system important to aquatic life.
However, few natural waterways contain androgens at concentrations high enough to disrupt this development. In some cases, the body will be grossly deformed, preventing if from swimming well. After attending the CBR symposium in October, LeBlanc became interested in testing samples of Fenholloway sediment to see if its androgens might disrupt development in water fleas there. LeBlanc notes that some aquatic species throughout the world are experiencing yet another pollution-induced masculinization, known as imposex. Affecting various populations of some 100 species of marine snails, this condition saddles both genders with grossly exaggerated male sex organs.