A recent preliminary survey of 11 animals here in the Puget Sound area (both Harbor Seals and Harbor Porpoises) has produced worrying results: 80 percent of animals sampled carried bacteria that were resistant to an antibiotic, and more than 50 percent carried bacteria that were resistant to multiple antibiotics.
“These animals are sentinels,” says Stephanie Norman, a veterinary epidemiologist with Marine-Med who is working to understand the causes and the prevalence of antibiotic-resistant bacteria in the region’s marine mammals—a project supported by a wide range of local and state organizations.
“Studying these animals gives us a nice profile of the health of the Puget Sound area,” she says.
Norman and her team plan to collect and analyze bacteria from a total of 138 Harbor Seals and Harbor Porpoises of different ages to build a more comprehensive picture of the scope of this problem in Puget Sound. This will help scientists better understand the risk that these bacteria pose to marine animals, as well as the humans, living in the area.
Wild animals aren’t routinely taking antibiotics to treat infections, but widespread antibiotic resistance in ocean creatures could still have a major impact on the conservation of endangered species. That’s because, as in the case of an ailing young southern resident killer whale that was administered antibiotics in 2018, veterinarians and others trying to rescue sick animals sometimes use these medications.
“If these are endangered animals, like the orcas that you have in Puget Sound, then it makes sense [to treat them], because saving one animal can actually save that whole population,” says Maria Palamar, a wildlife veterinarian and cofounder of Resolve Conservation, an organization that uses technology and citizen science to address wildlife protection issues. Along with the southern resident killer whales, antibiotics have also been used to treat wild Hawaiian monk Seals and Loggerhead Sea Turtles.
Antibiotic-resistant bacteria in marine environments could be dangerous to humans, too. Marine bacteria can cause skin infections in people with even small scrapes or insect bites, or food poisoning in people who eat contaminated seafood, especially for seafood eaten raw, such as oysters. In certain countries, like Brazil and Australia, oysters have been found to harbor antibiotic-resistant Vibrio parahaemolyticus or Escherichia coli (E. coli), both of which can be fatal to humans.
Scientists have yet to conclusively establish the source of antibiotic-resistant bacteria in Puget Sound, but humans likely play an important role says Linda Rhodes, an environmental microbiologist at the Northwest Fisheries Science Center. Culprits could include failing wastewater treatment or septic systems, runoff, and waste from livestock or even pets, she says.
Antibiotic resistance in marine animals is a problem that should concern everyone, not just conservationists, says Norman. “Animal health, human health, and environmental health are all connected,” she says. “You can’t really look at one without considering the other two. We ultimately are tied to the same water that these animals use.”
And this isn’t the first micro issue found in this region.
Puget Sound is a sound along the northwestern coast of the U.S. state of Washington, an inlet of the Pacific Ocean, and part of the Salish Sea. It is a complex estuarine system of interconnected marine waterways and basins, with one major and two minor connections to the open Pacific Ocean via the Strait of Juan de Fuca—Admiralty Inlet being the major connection and Deception Pass and Swinomish Channel being the minor.
Water flow through Deception Pass is approximately equal to 2% of the total tidal exchange between Puget Sound and the Strait of Juan de Fuca. Puget Sound extends approximately 100 miles from Deception Pass in the north to Olympia, Washington in the south. Its average depth is 450 feet] and its maximum depth, off Jefferson Point between Indianola and Kingston, is 930 feet. The depth of the main basin, between the southern tip of Whidbey Island and Tacoma, Washington, is approximately 600 feet.