Environment & Science

More lesions, tumors showing up on dolphins in Santa Monica Bay

The Ocean Conservation Society has identified more than 400 dolphins off the coast near Marina del Rey.
The Ocean Conservation Society has identified more than 400 dolphins off the coast near Marina del Rey.
Maya Sugarman/KPCC

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Researchers studying dolphins in the Santa Monica Bay have noticed an alarming trend: More and more are showing signs of skin lesions and even tumors.

It's believed pollution in the bay is weakening the animals' immune systems, leaving them vulnerable to viruses that cause these skin problems.

A study published in 2009 found that nearly 80 percent of common bottlenose dolphins (Tursiops truncatus) observed in Santa Monica Bay show at least one type of lesion.

They are also appearing on other species, such as the long-beaked common dolphin (Delphinus capensis), according to marine biologist Maddalena Bearzi.

She said this poses a "huge problem right now" for the charismatic creatures.

"They are pretty evident; you can’t miss them," Bearzi said. 

The lesions can be the size of a postage stamp, appear either light or dark like a bruise, and can cover an animal's entire body.

(A bottlenose dolphin covered in lesions. Photo via: ©2015mbearzi/oceanconservationsociety. Images taken under NOAA permit.)

Bearzi, originally from Italy, is co-founder of the Ocean Conservation Society, a nonprofit research group tracking marine mammals in the waters between Malibu and Rancho Palos Verdes.

She's been making surveys of the area almost every week for 17 years, compiling one of the longest running dolphin data sets in the world.

Over that time, Bearzi has documented a rise in lesions and even a small but noticeable uptick in tumors.

Pollution is the likely culprit.

"It affects their immune system,"leaving the animals open to viruses and other sicknesses that manifest in skin problems, she said.

(A dolphin with dark lesions swimming in the Santa Monica Bay. Photo via: ©2015mbearzi/oceanconservationsociety. Images taken under NOAA permit.)

Pesticides, PCBs and toxic metals like lead show up in the bay when rainwater washes in from dirty streets of the sprawling L.A. area.

One inch of rain can yield 10 billion gallons of this contaminated runoff, according to the nonprofit Heal the Bay.

"We know that [pollutants] transfers from mother to calves in the milk, so we know that some of the calves have high concentrations of these pollutants," Bearzi said.

Surveying the seas

Almost every week, Bearzi and a small crew of volunteers ship off from Marina Del Rey in a sleek, teak-stained sailboat dubbed "Mary's Triumph."

Their survey area runs from Point Dume in the north to Point Vicente in the south and sometimes as far out as the Channel Islands.

Volunteer Taylor Cook first heard about this project as an undergrad at UCLA.

She jumped at the chance to work with dolphins, since she's long loved marine mammals. On a recent survey, she was sporting dolphin tail earrings.

"I have pretty much [an] infinite number of marine mammal-themed jewelry," Cook said with a laugh.

She and other volunteers take turns logging data from dolphin encounters, as well as information on whales, sea lions and other ocean life.

Thanks to the GPS in their computer, each sighting will be geo-tagged with the exact location it occurred.

Right now, the team is focused on studying bottlenose dolphins. When they find a pod, Bearzi will quickly snap pictures.

Later, she can zoom in on those pics and identify specific dolphins by the unique pattern of notches each has on their dorsal fin.

In total, she’s seen more than 400 different individual bottlenose dolphins in the area.

She's even given them all nicknames, like "Pizza," "Mozza" and "Pane," after some of her favorite Italian foods.

Local pollution, regional problem

R.H. Defran, marine mammal researcher at San Diego State University, called this very important research.

He also studies dolphins and said he and others have used Bearzi's data to get a better sense of dolphin traveling habits.

It turns out some groups will swim up and down the Southern California coast, going as far north as San Francisco and as far south as Ensenada, Baja California in Mexico.

Because of this, policy makers need to know that pollution in Santa Monica Bay isn't just a local issue, he explained.

"It’s not that it just affects Santa Monica Bay dolphins; it affects dolphins up and down the coast as they pass through this area of pollution."

But, like the dolphins, this research is in trouble.

Bearzi’s work is funded by grants and donations, which she said are getting harder to come by.

"Unfortunately, you can conduct research only with money, and without money there is nobody here studying these animals," she said.

Her organization, the Ocean Conservation Society, is considering selling the "Mary’s Triumph" sailboat and working with a much smaller one to stay in operation.

Bearzi said that, even though she’s been at this for 17 years, there’s still plenty more she hopes to learn about these animals.