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Article: Cattle hormones seen affecting marine biology: feedlot runoff registers in minnow study.(National)(Brief Article)
- Article from:
- National Fisherman
- Article date:
- March 1, 2005
- Author:
CopyrightCOPYRIGHT 2005 Diversified Publications. This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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What people do on land can profoundly influence the health of aquatic life, as two new studies show.
Biology professor Edward Orlando of St. Mary's College of Maryland and colleagues have found that hormones leaked from cattle feedlots alter the reproductive biology of fish in nearby streams.
In a study of minnows from three streams feeding Nebraska's Elkhorn River, the scientists discovered that male fish exposed to cattle hormones had one-third the testosterone of upstream male fish. More to the point, the testicles of the downstream fish were half the size of their upstream counterparts.
Interestingly, the hormones had the opposite effect in ...