In Rio de Janeiro, sea turtles symbolize hope for clean water initiatives

RIO DE JANEIRO (CN) — Between the postcard-worthy views of Sugarloaf Mountain and Christ the Redeemer, Brazil’s green sea turtles glide through the murky waters of Guanabara Bay, offering an unexpected symbol of resilience in one of the country’s most polluted waterways.

Recently removed from Brazil’s endangered species list in 2022, these urban-dwelling turtles may now serve as living indicators of an ambitious cleanup effort in a bay that receives hundreds of tons of garbage, sewage and industrial waste daily from its surrounding seven cities, which are home to around 9.5 million people.

“They bring joy to my day. Tourists stop to take photos, and some even climb down the rocks to get a closer look,” said Bruno Machado, 29, who has been selling coconuts near the Estácio de Sá monument on Aterro do Flamengo for nearly a decade.

For longtime residents like Cristina Ackermann, who has walked along Aterro do Flamengo for 15 years, the turtles represent both wonder and worry.

“There are a lot of them here,” the 59-year-old businesswoman said. “But I’m struck by the number of turtles in this sea that isn’t clean. How do they survive?”

Preliminary monitoring by the Carioca Turtles project, which tracked 50 turtles in 2022, found that three out of every five suffered from fibropapillomatosis — a herpes-like virus that causes tumors, affecting their movement, buoyancy, vision and feeding.

“When we started, I felt disheartened by the turtles’ situation,” said oceanographer Gustavo Baila, a professor at the Federal University of Rio Grande and a collaborator on the project. Baila, who has worked with sea turtles since 2010, developed a technique for safely capturing them for study, using a combination of diving equipment and a lightweight, specialized net made of a fine mesh.

Recently, however, efforts to clean up Guanabara Bay seemed to be showing results. In 2023, the project monitored 106 turtles, with another 73 assessed so far this year — and the number and size of tumors appeared to be declining, according to Baila.

Biologist Ricardo Gomes, director of the Instituto Mar Urbano and a collaborator on the monitoring project, attributed improvements in water quality to the environmental restoration efforts led by Águas do Rio, a subsidiary of Aegea, Brazil’s largest private sanitation company.

Since taking over water management in Rio de Janeiro and 26 surrounding municipalities in November 2021, the company has invested around $700 million of a pledged $7.8 billion over a 35-year concession, making it one of the largest such projects in Brazil’s history.

“We had to restore people’s faith in the bay’s recovery. The first step was to get the public to believe in the project, and they only start to believe when they see results,” said engineer Caroline Lopes, an environmental manager at Águas do Rio.

Among the company’s completed projects, Lopes highlighted the unblocking of a sewage tunnel in the tourist-frequented South Zone, which had not been cleaned since 1970 and was 40% obstructed.

“This intervention prevented 43 million liters of contaminated water from flowing into Flamengo Beach daily. Across the entire bay, we’ve stopped 92 million liters of polluted water each day. We’re seeing this reflected in the bay’s ecosystem,” she added.

In a statement, Rio’s Secretary of Environment and Sustainability, Bernardo Rossi, announced the goal is to fully clean the bay within nine years.

“We’ve taken the first and most critical step with this concession and we won’t rest until we achieve universal access to sanitation,” he wrote, marking it as the largest social and environmental project in Latin America.

Still, scientists are cautious. Baila pointed out that the Carioca Turtles project does not aim to evaluate Guanabara Bay’s water quality. Gomes also noted that most visible improvements are concentrated in areas of the city’s South Zone, a relatively small portion of the bay.

Gisele Lôbo-Hajdu, a professor from the Rio de Janeiro State University who has studied green turtles since 2005, warns that it’s too early to draw conclusions.

“To make any definitive statement about the turtles’ health, we need years of monitoring and much more than three collections,” she said.

She also noted that preliminary data from another study, led by researchers at the Federal University of Rio de Janeiro, found antibiotic-resistant bacteria in the turtles — a further sign of ongoing environmental stress.

“There’s still a mismatch in the findings. But if we keep collecting data on other organisms and water quality, we might conclude in five years that the turtles’ health has improved,” said Lôbo-Hajdu. Despite the uncertainties, she believes the most hopeful sign is that studies are underway and more people are paying attention to the turtles’ preservation.