Written by Sarah Brown and Kashfi Halford
Just 60 kilometers (37 miles) from the city of Rio de Janeiro, dozens of Guianal dolphins swim gingerly alongside a motorboat, cutting through the water to breathe. Leonard Flach stands on the bow of the boat and takes photos, later identifying the individual based on his dorsal fin. The landscape of Sepetiba Bay is beautiful, with clear waters and forested mountains, but the water is far from clean.
The Guiana dolphin is “the most common dolphin species in Brazil, but also one of the most endangered,” says biologist and co-founder of the nonprofit Instituto Boto Cinza. Mr. Flach, a member of the Board of Directors, told Mongabay. He has been studying Guiana's dolphins in Sepetiva Bay since his 1990s, understanding the dangers they face and finding solutions to protect them.
One of the main threats to these dolphins is chemical pollution of the ocean. Flach was part of a recently published paper that found high toxin concentrations in Guiana dolphins (Sotaria guianensis) is the result of 12 years of dredging, industrial pollution and untreated sewage in Sepetiva Bay. Flach said up to 80% of the region's sewage is pumped into the bay untreated, contaminating the ocean with pathogens and pharmaceuticals excreted in urine.
“[Rio de Janeiro’s] “The Guiana dolphin, which lives in semi-enclosed bays, is one of the most polluted in the world,” Professor Mariana Alonso of the Institute of Biophysics at the Federal University of Rio de Janeiro, who was not involved in the study, told Mongabay. Ta.
Exposure to these chemicals is associated with hormonal changes and reproductive and immune system problems in Guiana dolphins, leading to increased susceptibility to infectious diseases, the study found. A viral outbreak among Guiana's dolphins from November 2017 to March 2018 was unusually deadly, killing at least 277 dolphins and killing almost a quarter of the population of Sepetiva Bay and the neighboring 6% of Guiana's population in the Gulf of Illia Grande became extinct.
“This virus was more deadly because it spread among people who were already in poor health,” Flack said.
Guiana dolphins are particularly vulnerable to contaminated water because they exhibit so-called “field fidelity” and rarely leave their birthplace. This means that no matter how polluted the water is, Guiana dolphins will continue to stick around, despite the health effects.
Dr. Flach studies Guiana dolphins in both Sepetiba Bay, a popular tourist destination, and neighboring Grande Bay. Ilha Grande's sea is more pristine than Sepetiba, and although there is less industry in the area, the sea is still polluted by oil companies and pollution coming from Sepetiba Bay. Alonso said high levels of mercury have also been recorded there, but studies have not yet confirmed whether the mercury occurs naturally or is related to industrial pollution.
Guiana dolphins once lived in the thousands throughout Rio de Janeiro, but their numbers have declined as the city has expanded. Of his three bays – Sepetiva, Isla Grande and Guanabara – where Guiana dolphins live, the hardest hit is Guanabara Bay, the famous ocean visible from Rio's iconic Christ the Redeemer and Sugarloaf. In the 1980s, Guanabara was home to over 400 Guiana dolphins. Currently, there are less than 30 of him left.
Saving Rio de Janeiro's most polluted bay
Guanabara Bay has a total surface area of 328 square kilometers (127 square miles) and is one of the most populous regions in South America, home to approximately 11 million people. It is also surrounded by the second largest industrial cluster, with around 10,000 industries, including chemicals, as well as 16 oil terminals and 12 shipyards. A 2017 study described Guanabara's development as “unmanaged, with limited or no planning for sustainability.”
Guanabara Bay's Guiana dolphins are under constant threat every day from industrial toxins, raw sewage, and noise pollution from ships that interfere with the dolphins' sonar. This combination causes chronic stress, which affects the dolphins' immune and reproductive systems, Rafael Carvalho, a biologist at Rio de Janeiro State University's Aquatic Mammals and Bioindicators Institute (MAQUA), told Mongabay.
Carvalho said females in the bay have been observed to never produce offspring, even though they reached sexual maturity years ago, which could mean they were having trouble reproducing. He said that this means that it is high. The chances of survival of calves that do manage to breed are “very low,” he added.
“That's exactly what these chemical components have on animal health,” Carvalho said. “It prevents them from breeding. That's why the population has declined so much over the past few years.”
Cleaning up Guanabara Bay and reducing daily pollution is a daunting task and requires multifaceted solutions. But progress is being made. Rio de Janeiro's water and wastewater services company, Aguas do Rio, announced that over the past two years it has carried out a series of infrastructure and technology developments in Guanabara Bay that have prevented 82 million liters of sewage from flowing into the sea. A company was dispatched to Mongabay.
When MAQUA researchers realized that a reserve established in the northern part of the bay in 1984 serves as a sanctuary for the Guiana dolphin, they realized the importance of the reserve and the need to create more. I emphasized.
“Through our monitoring, we have noticed that dolphins tend to spend a lot of time in or near that area of this reserve. This is probably because this reserve has low boat traffic and This may be due to some limitations in [such as fishing] And it retains some characteristics of better environmental quality,” Carvalho said.
Research to protect the Guiana dolphin
One way to understand threats to dolphins is to analyze carcasses to find out what killed them and what condition they were in before they died. But to get a clearer picture of the current health status of the population, researchers need to analyze living specimens.
At Sepetiva Bay, Flach puts away his camera and balances himself with a small harpoon-like device. Observing a school of dolphins, he took aim and fired a small arrow at the group, which hit one and immediately fell into the water, causing a commotion of splashing. With a roar of victory, Flach bent over the boat, scooped the arrow out of the water, and ripped off the last remaining chunks of fat and skin.
The biopsy causes mild discomfort but is not harmful, Flack said. For researchers, this chunk of meat is a valuable source of information for determining the dolphin's sex and measuring the toxic substances and pathogens stored in its fat. Flach will put it in a test tube and send it to researchers at the Federal University of Rio de Janeiro to analyze its contents.
Another way to monitor dolphin populations is through photography. In his office at Kunhanbebe State Park Center in Sahi, near Sepetiva Bay, Flach keeps thousands of images of Guiana dolphins breaking the water with their dorsal fins.
Each fin is unique, like a human fingerprint, and photos allow us to track dolphin numbers. He also recorded dolphins getting entangled in fishing nets and drowning. Bycatch, when marine animals such as dolphins and turtles are accidentally entangled in nets set for fish, is also a threat to Guiana dolphins, with up to eight dolphins dying in Rio de Janeiro each month.
Flach's research and work led to the creation of a 250 square kilometer (97 square meter) protected marine reserve in Sepetiva Bay, banning industrial and predatory fishing. He also co-ordinated a course that gave local youth a boat driver's license and provided them with alternative income from fishing by guiding wildlife tours such as dolphin watching instead of fishing.
“We need to provide alternative activities so that they can maintain their activities at sea and earn a living at the same time, without harming other animals or the marine ecosystem,” Flack said. he said.
The transition to ecotourism strengthens dolphins' relationships with local communities by increasing their economic value and increasing incentives to protect them and their environment. It also provides a way to earn a decent income as well as ensuring that traditional communities are not harmed as fish stocks have been severely reduced by industrial fishing.
Renan da Cruz Juvenal, a local fisherman turned tour guide, said: “Fish stocks are running out, so my only income is to work in ecotourism or leave my community to do something else on the mainland.'' source,” he told Mongabay. He lives in a quilombo (a community of descendants of enslaved Africans) on Marambaia Island in Sepetiva Bay and took Flach's course in 2014.
Through a combination of research, education, and public policy advocacy, we are making a significant impact on Sepetiva Bay's dolphin population. “We did a good job of pumping the brakes. Without the Guiana dolphin study, I think the mortality rate would have gone up,” Flach said.
Their existence is in jeopardy as their numbers are declining across Rio and there are very few remaining in Guanabara Bay. But experts say there's still hope. “We have to believe that there is a future. And we are working towards it for the preservation and future of this population,” Carvalho said. “Once you believe something is gone, it's gone.”
- About the authors: Sarah Brown (text) and Kashfi Halford (video)
- Source: This article was published by Mongabay
