INDIAN RIVER COUNTY — Everybody loves bottlenose dolphins. They are an emblem of the beauty and grace of the natural world and seeing one in the Indian River Lagoon adds a bit of magic to the day.
When a pod passes under the Barber Bridge, the sight stops walkers in their tracks and pulls casual strangers into a friendly group as they watch the animals - which one writer calls the most playful in the universe - breach and dive.
They seem the happiest of creatures living marvelous lives, but the view from the bridge and the boat and the waterfront restaurant is deceiving, because the dolphins in the Indian River Lagoon are sick and dying.
The most recent scientific studies found more than 50 percent of them are ill and that they live, on average, only half as long as their free-ranging kin out in the relatively clean Atlantic.
"We were shocked," says Stephen McCulloch, head of the Marine Mammal Research and Conservation Program at Harbor Branch Oceanographic Institute, referring to results of a dolphin health study.
"What we are seeing is not just concerning, it is alarming. Nowhere else do you see this combination of known and unknown diseases, including viral, bacterial and fungal diseases and cancers."
Troubling as it is to think of these amazing mammals swimming with disease-deformed fins and suffocating in red tides created by fertilizer run-off, there is a still more disturbing aspect to what scientists call an epidemic among Indian River Lagoon dolphins.
"They are the sentinel species for the Treasure Coast," says McCulloch, "the 400-pound canary in the coal mine."
"What happens to them happens to us," says world-renowned marine biologist Edie Widder, founder of Ocean Research and Conservation Association (ORCA) in Fort Pierce.
And of course, what is happening to them is being caused by us.
The Indian River County human population quadrupled between 1970 and 2010, growing from 35,000 to nearly 140,000, and that's typical of the entire five-county region bordering the lagoon. None of the people moving in came with the idea of polluting the lagoon or making dolphins sick but byproducts of that population increase are doing most of the damage.
"I think there is a large body of evidence being developed that points to degradation of the environment that affects the overall health of the ecosystem," says Adam Schaefer, a Harbor Branch research scientists studying the build-up of mercury in marine mammals and people. "We are seeing astronomically high levels of mercury in dolphins and increased levels in people who live near the lagoon and consume a lot of fish. There is a need to protect the lagoon and protect dolphin health because it all ties into human health."
Among dolphins, high mercury levels affect endocrine and liver function while studies have found impaired neurodevelopment in children exposed to excess mercury in the womb.
"I came to the lagoon in 1996," says McCulloch. "Adjacent development was taking place at a rapid pace, but it was still fairly pristine.
"The more I learned about the national importance of the estuary, the more impressed I was. There are 3,715 species of plants, birds and animals living in this environment.
"The lagoon is a rare treasure. It is a living, breathing organism of tremendous ecological significance, and it is very delicate. The water is shallow and there isn't much water exchange because it is mostly enclosed by the barrier islands. What goes in the lagoon stays in the lagoon."
As part of his research, McCulloch began photographing the dorsal fins of bottlenose dolphins, which are unique, fingerprint-like identifiers.
"We started to see unusual skin diseases when we examined the photos," says McCulloch. He also found dolphin carcasses floating in the water and saw viral infections.
In 2003, along with former Harbor Branch Research Professor Greg Bossart, McCulloch initiated the Dolphin Health and Risk Assessment (HERA) Project, beginning a comprehensive, multi-year study of lagoon dolphins.
Each year, detailed physical examinations are conducted on 40 conscious, gently-restrained dolphins in order to evaluate their general condition, and a suite of blood, feces, urine and other biological samples are collected and distributed to over a dozen scientific collaborators for analyses.
In a 2006 article published in the Journal of the American Veterinary Medical Association, McCulloch and his colleagues reported finding lobomycosis in 30 percent of dolphins in the southern part of the lagoon.
A comparable population of dolphins studied in Charleston, S.C., showed no evidence of the disease.
Lobomycosis is a nasty fungal infection. It's not fatal but opens wild dolphins to potentially fatal secondary infections when hard fungus-infested skin cracks and lets in contaminants.
The disease is widespread among humans in the tropics but for unknown reasons has not spread to humans in Florida at this time.
Still, according to Schaefer, it is possible humans could contract the infection from swimming in the lagoon with an open sore or wound since it is breeding among marine mammals.
There is no cure for the disease, other than cutting away the infected tissue.
Indian River Lagoon dolphins also have a high occurrence of two new types of viruses, according to Widder and fellow ORCA scientist Sarah Frias-Torres. "There's a herpes virus, and a papilloma virus, causing cancer-like lesions in the tongue, skin and genitals. Throughout the resident dolphin population, the cancer-like tumors are occurring at epidemic proportions."
Both the diseases and the fungal infestations are taking hold in dolphins because their immune systems are depressed by what scientists call environmental stressors - which means pollution.
The pollution comes from a range of sources, including road runoff carrying oil, gas, toxic dust from brake linings and other contaminants and the atmosphere, which carries mercury from distant locations that ends up in the lagoon.
But the biggest source of pollution is excess fertilizer that runs off into the lagoon when it rains, along with other organic material such as grass clippings and palm fronds.
The fertilizer and yard waste lead to nutrient loading, excess nitrogen and phosphorous that feed the growth of poisonous algae.
The algae blocks sunlight and consumes oxygen, killing sea grass, fish and eventually, mostly in secondary ways, dolphins.
Bottlenose dolphins are adapted to the mix of fresh and salt water the lagoon has contained for centuries and do not fare well in an environment overloaded with nitrogen and other organic chemicals.
"Fertilizer is one of the largest and most detrimental [pollutants] to the ecosystems," says Warren Falls, ORCA's managing director. "In addition to nutrient loading of the lagoon, the nitrates from fertilizer bond with mercury in the soil and waters and are then digested by bacteria producing methyl mercury."
In its basic form, mercury is inorganic and cannot enter the food web.
Once processed into methylmercury, it gets into small fish that are eaten by bigger fish that are eaten by dolphins and humans.
The good thing about fertilizer being the worst source of pollution is that people can change the type of fertilizers they use and the ways they use them so that large amounts don't run off into the lagoon.
"We are trying to do good science to inform the public and give policy makers the information they need" to correct problems, says McCulloch.
After hearing a presentation by Dr. Widder, the Vero Beach City Council in January voted unanimously to enact an ordinance regulating fertilizer use and prohibiting organic material in canals and the lagoon.
"I think it is a very important ordinance to try and protect the lagoon," says Vero Mayor Pilar Turner.
Other cities and counties along the lagoon have enacted similar ordinances and if more follow suit the epidemic of disease among dolphins may begin to recede.
According to scientists, people caused this problem and they can go a long way toward correcting by abstaining from fertilizer use during the rainy season and applying slow-release fertilizer the rest of the year.
"Without question these fertilizer ordinances are good for lagoon health," says McCulloch. "It is common sense."