The salty Louisiana winds ruffle Forrest Gomez’s hair as her team’s motorboat crashes into the warm waves of Barataria Bay. The inflatable black Zodiac suddenly carchunk to a halt beside a small fleet of other research vessels. All are equipped as floating labs.

Scientists in a boat throw nets into the water. Dragging the net behind them, they slowly run in circles to catch the bottlenose dolphins they study.

“GO, JUMP NOW” someone shouts. More than 60 marine mammal veterinarians and assistants will splash you down the side of the boat into shoulder-deep water. As they walk towards the dolphins, they bring their instruments behind them.

Dodging the spray of water from its muscular tail, Gomez and crew untangle the animal, place it between the two, and prepare it for a number of tests to assess its health.

Wildlife at Barataria Bay in southeastern Louisiana on the Gulf of Mexico was hit hardest by the 2010 Deepwater Horizon oil spill. Nearly 200 million gallons of oil (the equivalent of 300 Olympic-size swimming pools) seeped into the Gulf Coast after BP’s drilling rig exploded, making it one of the worst environmental disasters in U.S. history.

Gomez, medical director of the National Marine Mammal Foundation, used a floating ultrasound system to investigate how the mothers of Barataria Bay dolphins have lived since the spill.

She wears chunky goggles and a chunky black hood so she can see the screen even in the scorching sun. On top of that: scans of fetal baby dolphins. Water can easily obtain sharp images that are on par with gels used on the belly of pregnant human mothers.

    Cynthia Smith ultrasounds wild dolphins on the deck of a research vessel

National Marine Mammal Foundation


Cynthia Smith checks wild dolphins on the deck of a research vessel in Georgia. Also pictured are NMMF’s Brenda Bauer, Veronica Sendejas and Randall Dia.

Along with whales and porpoises, dolphins are one of a group of marine mammals known as “cetaceans” that carry offspring and give birth to live babies in the womb. Studies have shown that post-spill dolphins have about a 1 in 5 chance of successfully conceiving, which is very low compared to 2 in 3 healthy control populations. Scientists believe that the oil weakens the dolphin’s stress response, immune system, and lungs, making the mother more susceptible to illness and possibly the loss of her baby as a result.

“It’s like a perfect storm,” Gomez said.

Reproductive failure is just one of the serious health impacts dolphins continue to face 12 full years after the oil spill. Yet the funds set aside for the disaster — a record $18.5 billion, including $5.5 billion in Clean Water Act fines — are leading to unprecedented investment in new tools and science.

Long-term, focused research has allowed scientists like Gomez to define normal dolphin pregnancy conditions. After over a decade of refinement, her full-body ultrasound scan now takes her only 10 minutes.

    Ultrasound image of a dolphin fetus

National Marine Mammal Foundation


Ultrasound images of dolphin fetuses: (A) eye, (B) stomach, liver, lungs, (C) male genitalia, (D) female genitalia.

The researchers hope to apply this expertise to other marine mammal species. Breeding is important for understanding population growth and decline. Such knowledge can help with conservation decisions and planning for crises, Gomez said.

“There is no doubt that Deepwater Horizon has facilitated many of these techniques,” said Gomez.

illustration of pregnant dolphin

Veronica Sendejas


National Marine Mammal Foundation

Long-term research has allowed scientists to define the conditions for a normal dolphin pregnancy, including a picture of what a first pregnancy should look like.

All this new science could help us deal with coming threats, from declining water quality to worsening red tides, researchers say. Dolphins are likely to be the first to experience the adverse effects of contaminated water, so what happens to dolphins may also happen to humans in the future.

“Dolphins are the guardians of ecosystem health,” said Randy Wells, director of the Sarasota Dolphin Research Program at the Zoological Society of Chicago, who has studied dolphins for more than 50 years.

The question is whether humanity will continue to invest.

Damage measurement

Bottlenose dolphins are one of more than 30 species of dolphins in the world. They can grow up to 13 feet, or nearly as long as a Volkswagen Beetle. Females are known to live up to 67 years, and males up to 52 years, in populations studied over time, Wells said.

They display a high level of intelligence and problem-solving ability. Bottlenose dolphins also have complex social interactions, with many living in residential communities and interacting with the same individuals throughout their lives. They tend to stay in the same home range even in the face of oil spills, hurricanes, or other threats to the environment.

A dolphin with its head out of the water and two dolphins with their fins out of the water

National Marine Mammal Foundation


Bottlenose dolphins grow up to 13 feet long, about the same length as a Volkswagen Beetle.

Len Thomas once joined a team studying these dolphins in Barataria Bay. But after a ecostatistician at the University of St Andrews in Scotland was attacked by an “angry stingray” and rushed back to dry land with thorns sticking out of his feet, he took the dolphin out of safety on a Zoom call. decided to crunch the data in

Baseline data on pre-spill dolphin populations were scarce and researchers were able to analyze little. But then scientists had to quantify the oil impact and determine how much money and restoration governments needed.

It was a complicated process. Ryan Takeshita, a researcher who worked to assess the damage, said simple death tolls may have underestimated the damage.

“We didn’t want to just think about dead dolphins,” said Takeshita, now deputy director of conservation medicine at the National Marine Mammal Foundation.

Statistician Thomas predicted it would take about 35 years for the dolphins to recover to 95% of their original population, but he wanted a clearer picture of the effects of the spill.

Using data gleaned from health assessments, Thomas came up with a demographic measurement that provides a more accurate picture of dolphin recovery: The Year of the Lost Whale.

“For all the individuals that could have been there, it’s the difference between the years they had and the years they could have had,” Thomas explained.

Final figures from his model: The spill eliminated 31,000 whale-years, in addition to the more obvious damage.

“There are things that apply to basically any cetacean species,” he said. “The modeling framework is there.”

In the future, Thomas hopes to collect more baseline data for marine mammal scientists to refer to if another disaster strikes.

The graph shows scientists wondering what the trajectory of the Barataria Bay dolphin population might have been if the oil spill hadn't happened.

The blue line shows what scientists think the trajectory of the Barataria Bay dolphin population might have been if the oil spill hadn’t happened. The red line shows the model’s prediction of the true Barataria bay dolphin population. The ‘lost whale year’ is calculated as the sum of all annual differences between these population sizes (total area between blue and red lines).

bottlenose beat

Barb Linehan, deputy director of animal health and welfare at the National Marine Mammal Foundation, said once the scientist was bottlenose and in the water, “it’s like a really well-organized circus.” Collect data and release dolphins as soon as possible.

For Linnehan, a cardiologist, this meant honing a new technique for listening to dolphins’ heartbeats. Prior to the oil spill investigation, wild dolphin hearts had not been studied. There were no agreed standards for monitoring the heart.

“The foundation had not yet been laid,” Rinnehan said.

After months of practice, Linehan’s team nailed the 5-minute method. The vet reached his hand between the dolphin’s front fins and tilted it sideways for the best angle. They then used a very long waterproof stethoscope to listen to the dolphin’s heartbeat, or grabbed an ultrasound wand connected to his floating yellow ECG machine to take pictures of the inside.

    Barb Linehan and Sharon Houston performing a water center echo scan

National Marine Mammal Foundation


Barb Linehan and Sharon Houston performing a hydrocentric echocardiogram (cardiac scan) on a wild dolphin during a health check-up in Barataria Bay, Louisiana.

The team’s investigation reveals that the Barataria Bay dolphin heart is unusual. Compared to healthy wild dolphins in Sarasota Bay, the walls of the ventricles (the part of the heart that pumps blood to the rest of the body) are thinner than normal, which could be related to oil pollution. Yes, said Rinnehan.

After perfecting the technique and applying it to other populations, Linnehan’s team discovered another surprising fact. Most of the dolphins studied had harmless heart murmurs.

Dolphins have large, muscular hearts that pump blood very quickly. Sometimes this causes an extra buzz, or murmur, in their heartbeat. This phenomenon is also seen in other athletic mammals such as sled dogs, race horses, and even human marathon runners.

Knowing that these noises are normal is important to both traditional dolphin veterinarians and those studying future ocean crises.

In retrospect, scientists should have been studying wild dolphin hearts from the beginning, Linehan said.

“It’s unfortunate that it takes such a large-scale environmental disaster for people to actually notice and care,” she said. “But we need to harness the momentum.”

swim in uncertainty

The many benefits of these innovations are already evident.

For one, Thomas’ model has already been used to measure the potential impacts from Middle Barataria sediment diversion, a project aimed at restoring erosion caused by oil spills. increase. Some scientists believe it ultimately reduces the salinity or salinity of the water.

Thomas predicts that this low salinity would be “absolutely devastating” for dolphins in Barataria Bay.

“This makes Deepwater Horizon look like a walk in the park,” says Thomas. “If it continues for years, it will effectively destroy the population.”

Initial restoration funding from Deepwater Horizon has dried up, but researchers stress the importance of investing in such science so that such research can continue.

Beyond tracking the health of dolphins after a spill, scientists like Gomez hope to pursue other important projects, such as strengthening rehabilitation and rescue efforts for stranded animals.

“The fundraising has been very influential, but the story isn’t over,” Gomez said.

Given the enormous amount of drilling in the Gulf Coast, Florida is fortunate that it has not experienced the effects of a devastating oil spill comparable to Louisiana, Welles said.

“It is a foolish business to believe that nothing is going to work,” said Wells.

Climate change poses another water quality threat as pathogens survive longer in hot water. With nutrients from agriculture, septic tanks and sewage infrastructure not designed to handle Florida’s burgeoning population, red tide continues to worsen, killing dolphins and the prey they rely on. Long-term pollutants and debris clog waterways.

“When controls are not put in place to control the pollution that flows into the water, it’s pushing ecosystems past tipping points,” Wells said. “We need to give ecosystems a chance to bounce back.” there is.”

While dolphins are likely to be at the forefront of these threats, Wells said humans could feel the effects as well. We are mammals that depend on clean water for life.

This article is part of the UF College of Journalism and Communications series WATERSHED. This is a statewide survey of water quality in honor of his 50th anniversary of the Clean Water Act, supported by the Pulitzer Center’s national Connected Coastlines report initiative.

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