Sewage Effluents Impact Fish Reproduction
Posted on: Tuesday, 16 January 2007, 09:00 CST
U.S. scientists say sewage plant effluents not only affect individual aquatic organisms, but also entire aquatic populations, reducing long-term viability.
It's known sewage treatment plants release estrogens that can cause changes in the gender of an individual fish or invertebrate, but the long-term consequences to populations were unclear. The new University of Minnesota study confirms such estrogens can have population-level impacts.
The researchers found effluent exposure reduced male fish aggressiveness and ability to successfully compete with unexposed males for a nest. The exposed fish were less able to attract a female and successfully reproduce.
But while estrogens had a negative impact on fathead minnow reproduction, the researchers found exposure to a male hormone showed opposite results. Exposed fish were more aggressive than unexposed fish, and they competed better for nests, thus producing a greater number of eggs.
The study is published in the current issue of Environmental Toxicology and Chemistry.
Source: United Press International
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