Rays thrive beneath polluted surface of Rio’s Guanabara Bay

By Maria Angelica Troncoso

Rio de Janeiro, Apr 2 (EFE).- To the amazement of scientists, a wide variety of rays have carved out an environmental niche amid the highly polluted waters of Rio de Janeiro’s Guanabara Bay, but their continued survival is under threat from unabated contamination and the ray’s popularity in Brazil as a source of cheap protein.

The existence of the colony, which includes species ranging from the spotted eagle ray, which measures more than 3 m (11 ft) long, to the much smaller Brazilian guitarfish, was revealed to the world by the acclaimed 2017 documentary Urban Bay (Baia Urbana).

The film was the work of biologist Ricardo Gomes, director of Instituto Mar Urbano (Urban Sea Institute), a group devoted to preserving biodiversity in Rio’s waters.

Gomes recounted his first encounter with the rays in an interview with Efe.

“In the nearly 30 years I have been diving in Rio de Janeiro that was the most incredible thing I have seen,” he said.

Covering nearly 400 sq km (154 sq mi) and dotted with numerous islets, Guanabara Bay is fed by 35 rivers and is home to hundreds of species.

As an ecosystem, the bay ranks fifth in the world in the number of confirmed ray species with seven, while three others remain under study.

Every day, according to biologist and environmental consultant Mario Moscatelli, untreated waste water from roughly 4 million Rio residents flows into Guanabara Bay.

Noting that “hundreds of millions of dollars” have been spent since 1994 to address the situation, he told Efe that the problem is not money, but “the poor management of resources from both the economic and technical viewpoints.”

In the short term, Moscatelli and Gomes are less concerned about pollution than about Brazilians’ taste for ray, especially for the critically endangered Brazilian guitarfish, known here as the “viola.”

Popular for its flavor and low price, the Brazilian guitarfish is part of the fare served to children in Rio’s public schools, a practice Gomes said is bad both for the survival of the species and for public health.

“Guanabara Bay is very polluted with metals and the rays are at the bottom, where those metals accumulate,” he pointed out.

The area of the bay where the rays dwell is now facing the possibility of encroachment in the form of a proposed lengthening of the runway at Rio’s Santos Dumont Airport.

Rio de Janeiro is heavily dependent on tourism and Gomes hopes to persuade the powers that be of the value of rays as an attraction for dive tourists’ willing to pay for the privilege of observing the “marine butterflies” in their natural habitat. EFE mat/dr

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