Like humans, Indian River Lagoon Dolphins develop antibiotic-resistant bacteria, study shows

Data from dolphins can help understand antibiotic resistance in people

By Charlotte Trattner - Digital Intern

A new study confirmed bottlenose dolphins in Florida's Indian River Lagoon are susceptible to antibiotic-resistant bacteria which can also be harmful to humans. 

The research comes from 13 years of data from Florida Atlantic University's Harbor Branch Oceanographic Institute, the Georgia Aquarium, the Medical University of South Carolina and Colorado State University. The researchers studied a total of 171 bottlenose dolphins in the Indian River Lagoon. They identified 88.2 % of the 733 pathogens were resistant to at least one of the 17 antibiotics. 

The bottlenose dolphin is a sentinel species, meaning they can determine potential environmental health hazards for humans. Adam M. Schaefer, lead author and epidemiologist at FAU's Harbor Branch, said antibiotic-resistant bacteria is a major public health concern. 

A global health threat

"This is a global threat that many organizations including the World Health Organization, have put as a priority health concern because we have some of these infections diseases which are incredibly hard to treat," Schaefer said. 

Some of the antibiotics to which the bacteria are resistant include erythromy­cin, ampicillin and cephalothin.

Studying these particular dolphins is important because humans share the water with these creatures, making people susceptible to the same bacteria. 

"People use the waterway for recreation, for fishing, some commercial fishing goes on as well, some clam and oyster folks that are collecting, you know, seafood from the lagoon," Schaefer said. "So, (dolphins) are actually a really good indicator because they live in this coastal environment that's just closely bordered by humans, and humans are using the same water and even eating some of the same fish."

The study collected samples and swabs from the water mammals' blowhole, fecal swabs and gastric swabs of microbes and pathogens. The study cultured bacteria strains to help identify potential health trends. 

What's causing antibacterial resistance and how to help

According to Schaefer, there are two different factors causing the resistant bacteria. 

"One is that the resistant bacteria themselves are getting into the lagoon where these dolphins live, and that can be through, you know, discharge, septic tanks, all sort of canals even just runoff from land," Schaefer said. "The other route is that the antibiotics, these drugs themselves, are getting into the aquatic environments and that's because most sewage treatment doesn't necessarily breakdown these medications." 

There are several ways to mitigate this problem. Schaefer suggests physicians and care providers only prescribe antibiotics when necessary, and people need to learn how to properly dispose of their unused antibiotics.

"Flushing them down the toilet is not the recommended way to dispose of those things," he said.

What else dolphins can tell us about human health problems

Antibiotic-resistant bacteria isn't the only common health problem humans share with dolphins. A previous study with the Marine Resource Council identified high mercury levels between dolphins and fishermen. 

The Marine Resource Council, a nonprofit organization that uses science to guide programming, local and political decision-making, evaluates different restoration projects and advises a course of action.

Leesa Souto, the Executive Director of MRC, isn't surprised to learn about the potential problems. 

"Yes, we are contaminating our lagoon with wastewater and it's resulting in a major impact to one of our charismatic fauna, you know the dolphins in the lagoon that everyone knows and loves so well, they're suffering as a result," Souto said. 

She says she recognizes the importance of the study. 

"We live in a coastal zone, we are a coastal species, you know," Souto said. "We are in Florida because we love the water, and yet we continue to contaminate it all the time and pretend it doesn't affect us." 

Souto said humans share the lagoon and now both mammals are suffering alongside it.

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