This is the first article I have seen about antibiotic havoc on wildlife.
Manure runoff contains nitrogen and phosphorus, which can drain into the Chesapeake Bay and cause harmful algal blooms. Other contaminants usually go along for the ride, such as medications given to the livestock: antibiotics, antiparasitic medication, and even painkillers.
In 2017, the U.S. Food and Drug Administration reported that more than 22 million pounds of antimicrobials—which includes antibiotics and antiparasitics—were sold in the U.S. for use in livestock alone. Considering there are nearly one billion cows around the world—not to mention chicken, pigs, sheep, and horses—a staggering amount of livestock pharmaceuticals are entering the water, both freshwater and marine, experts say. And from birth control hormones feminizing male fish to painkillers poisoning vultures, the impacts of such drugs on wildlife are more far-reaching than previously believed.