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. The males go into a reproductive mode that never shuts off.
Affected females can develop a huge penis that blocks their release of eggs.
The resulting egg-engorged females eventually die. The one agent now known to trigger this excessive masculinization is tributyl tin. It's not an androgen, but a toxic compound used to retard barnacle development on ship hulls. How this pollutant masculinizes the snails remains a mystery. Some female fish change into males in response to local sex ratio or social cues.