Antibiotic resistance among wild dolphin populations in Florida’s Indian River Lagoon has been on the uptick since 2009, a new study by researchers at Florida Atlantic University’s Harbor Branch Oceanographic Institute found. 

Antibiotic resistance occurs when bacteria develop the ability to defeat the drugs designed to kill them. Researchers say the increase is likely due to antibiotics entering marine environments.

How we know this. 

The researchers, in collaboration with the Georgia Aquarium, Medical University of South Carolina, and Colorado State University, conducted the study from 2003 to 2015. Using 13-years’ worth of data, the researchers identified 733 pathogens from 171 bottlenose dolphins by taking swab samples from the blowhole, gastric fluid and feces. The dolphins were captured and released back into the Indian River Lagoon. Using the Multiple Antibiotic Resistance (MAR) index, a tool used to determine antibiotic resistance, researchers found that the overall prevalence of resistance to at least one antibiotic was 88.2%.  

Why it matters.  

Antibiotics are routinely used to treat or prevent infectious disease, and in agriculture to suppress bacterial diseases and promote the growth of livestock and crops. But, public health experts say antibiotic resistance is one of the biggest public health challenges of today — many common bacterial infections are developing resistance to the drugs used to treat them faster than new drugs can be developed. At least 23,000 die annually in the U.S. from antibiotic-resistant infections. 

But, this study shows resistant strains of bacteria aren’t confined to land — they are also present in the marine environment, likely due to growing coastal populations. Experts say up to 80% of an antibiotic dose passes right through the body, meaning most will end up in waste water. And, research shows that waste water treatment plants don’t remove antibiotics very well. Bottlenose dolphins are a valuable species in helping scientists understand how this affects human and environmental health. 

One worrisome result from the study is that resistance increased significantly for a common pathogenic marine Vibrio species found to cause seafood-poisoning. 

What’s next?   

The authors say their findings show that resistance to antibiotics in bottlenose dolphins is prevalent.  

“We’ve been able to provide a large database of information in order to continue learning from these impressive animals,” Gregory D. Bossart, senior vice president and chief veterinary officer at Georgia Aquarium, told FAU news.  

Where can I learn more?  

Kudos to:  

Co-authors of the study are Tyler Harrington, FAU’s Harbor Branch; Patricia A. Fair, Ph.D., Medical University of South Carolina; and John S. Reif, Ph.D., Colorado State University. 

This work was funded in part by the Protect Wild Dolphin License Plate funds granted through the Harbor Branch Oceanographic Institute Foundation and Georgia Aquarium.