Horseback riding along the causeway in Florida has been a popular activity for tourists and locals alike. However, concerns have been raised about the potential pollution of the bay caused by horse manure. A recent study conducted by the University of Florida used DNA testing to analyze the water quality of the bay before and after a group of horses had passed through. The results showed that the levels of E. coli bacteria increased significantly after the horses had passed, indicating that horse manure was indeed a source of pollution. The study also found that the levels of E. coli bacteria decreased over time, suggesting that the bay was able to naturally cleanse itself. However, the researchers recommended that horse owners take steps to minimize the amount of manure that enters the bay in order to protect water quality.