Current Dolphin Deaths May Indicate Future Health Problems For Humans
Nearly 800 bottlenose dolphins have died so far in an unusual mortality event (UME) that began in July along the coast of New York and is progressing south following the dolphins’ seasonal migration pattern. (See the number of dolphin deaths by state here.) Gregory Bossart, V.M.D., Ph.D., who is senior vice president of animal health, research and conservation at Georgia Aquarium, says dolphins are the ocean’s “canaries in a coal mine” and wants people to understand ocean health, dolphin health and human health are interconnected.
The current mid-Atlantic UME appears to be caused by cetacean morbilivirus, a virus related to measles in people and distemper in canines. “Cetacean morbillivirus typically is a highly lethal dolphin disease. It first emerged in the late 1980s causing an epizootic — a disease that is widespread within an animal population — that impacted dolphin populations along most of the Atlantic coast of the United States. By the time it was over, about 750 dolphins had died,” said Bossart.
Bossart has spent 30 years working in wildlife pathology, both nationally and internationally. He is on the National Oceanic and Atmospheric Administration’s investigative pathology team for this UME, as well as the one investigating another UME in the Indian River Lagoon (IRL) in Florida, which means he is one of the pathologists who analyze tissue samples from the dead dolphins to determine the cause of death. He also leads a Health and Environmental Risk Assessment (HERA) study of dolphins in the IRL and in Charleston, S.C. The study is based at Harbor Branch Oceanographic Institute at Florida Atlantic University and conducted by staff at Georgia Aquarium’s Conservation Field Station in St. Augustine, along with other partners.
HERA started in 2003 to characterize dolphin health and learn from dolphins as sentinels for ecosystem and human health. Over the 10 years of the study, HERA has documented novel emerging disease; zoonotic disease, which is transmitted between animals and humans; antibiotic resistant bacteria; immune dysfunction; and high levels of toxins like mercury in IRL dolphins. Many of these conditions have direct public health implications, whereas others may indicate an environmental distress syndrome that could eventually affect humans.
One of the symptoms of environmental distress syndrome is old diseases like cholera, malaria and tuberculosis re-emerging, while new diseases — such as this cetacean morbilivirus — start emerging. Bossart reports that this phenomenon has been occurring over the past four decades.
“The important thing to understand is that dolphins serve as a type of environmental early warning system for environmental change that has the potential to impact public health. The dolphins are becoming sick because the oceans are becoming sick. And although people try to remove themselves from natural forces, they still affect us,” Bossart said. “No matter where we live, the ocean affects everything from our ability to breathe, to our food availability and quality, to the weather — and all of that affects the economy. We need to care about ocean health because our lives depend on it.”
In addition to the mid-Atlantic and Indian River Lagoon UMEs, there is a dolphin UME happening now in the Gulf of Mexico. Bossart cannot recall a time when three separate UMEs affecting a single marine mammal species were going on at the same time. “It’s not one UME that we should be necessarily concerned about. It is the increasing combination of aquatic animal health problems over time. It’s true that three different UMEs are happening at once that affect bottlenose dolphins, but we’re also seeing this same pattern with other species around the world. Ultimately, it is in our own best interest to investigate all wildlife health patterns that could potentially affect our own well-being, since three-fourths of all emerging infectious diseases of humans are zoonotic, most originate in wildlife, and their incidence is increasing,” said Bossart.
Regardless of where they live, by helping dolphins, people can help protect the ocean, which is good for all of us. Here are some ways people can help:
- Be seafood savvy and consume seafood that is caught sustainably. This helps reduce demand for species that are already depleted.
- Purchase only tuna labeled “dolphin safe.” It indicates that the tuna fish were caught in a way that does not harm dolphins.
- Plant native, insect-resistant plants in your yard. They use less water and require less pesticide, which means poisons do not flow into the water supply.
- Participate in a beach, lake or stream clean-up in your community.
- If you go to the beach, admire wildlife from a distance and don’t remove rocks or coral. Pick up after yourself – leave the beach and water better than you found them!