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Amazon tragedy as endangered river dolphins die in hot water

Ali Wood

Ali Wood

Ali is WDC's education projects coordinator. She is the editor of Splash! and KIDZONE, our magazine and website for young supporters.

The climate crisis is accelerating at such an alarming rate that some whale and dolphin populations haven’t got time to adapt. More frequent and severe droughts and heatwaves are threatening the survival of species and ecosystems that are crucial to our own existence. When 155 endangered river dolphins died suddenly in Lake Tefé in Brazil, this heartbreaking event gave us a stark warning of the severity of the situation.

*Please note that this blog contains some distressing photos.

Amazon River severe drought due to lack of rainfall and high temperatures
The Amazon river is dropping by 30cm each day over the past few weeks.

The level of the Amazon, the world’s biggest river, has fallen by 30cm each day over the past few weeks. © Miguel Monteiro, Mamiraua Institute

The Amazon rainforest holds a fifth of the world’s flowing freshwater, is one of the planet’s largest carbon sinks, absorbing and storing carbon dioxide from the atmosphere and is known as the ‘lungs of Earth’ because it generates 20% of Earth’s oxygen. Its survival is key in our battle against the climate crisis. Yet, it’s the very same crisis that now places this precious ecosystem in jeopardy, so it’s vital we protect it. With Earth’s average temperatures reaching a new record high during August and September this year, the Amazon is grappling with catastrophic drought, causing water levels to plummet dangerously low. The rainforest is drying out and catching fire as rivers run dry, while the temperature of the water that remains rises to temperatures unbearable for the species that call it home.

© Fernando Trujillo/Fundacion Omacha
© Fernando Trujillo/Fundacion Omacha

Can you help protect these vulnerable dolphins from extinction?

River dolphins are top predators in these ecosystems and serve as an important indicator of river health. The alarming mass deaths of both Amazon River dolphins, locally known as botos, and Tucuxi River dolphins send a clear message: the Amazon’s rivers are in trouble, and so are we.

Amazon River dolphin dies after drought and extreme heat
Without river dolphins, the Amazon River will suffer. © Miguel Monteiro Mamirauá Institute

In Brazil’s Amazon Lake Tefé, water temperature soared to 39.1 degrees Celsius (102.4 Fahrenheit) – a staggering nine degrees Celsius higher than normal at this time of year - comparable to a hot bath you might soak in at home. This shocking and unhealthy rise in water temperature has proved too much for river dolphins and other aquatic wildlife to endure. Reports from wildlife experts describe river dolphins swimming in circles, clearly suffering, disorientated and unable to dive and behave as they normally do. While the exact causes of this mass die-off event are still being investigated, the abnormally warm water may have caused the dolphins’ organs to fail, or they may have been poisoned by toxic algal bloom which has proliferated in the lake, staining the water red.

Testing the temperature of the Amazon river after mass death of river dolphins
The Amazon River reached a shocking 38.2 degrees Celsius

The cause of death is still open to discussion, but the main suspect is heat stress. © Miguel Monteiro Mamirauá Institute

The situation leaves little room for escape. Smaller river tributaries have dried up, completely isolating and trapping river dolphins and manatees, increasing their risk of stranding and overheating as they are unable to reach cooler water.

Amazon River dolphin
It's heartbreaking to think what these sentient dolphins had to endure as the temperatures rose. © Fernando Trujillo/Fundacion Omacha

Botos are found exclusively in the rivers and lakes of Brazil, Bolivia, Venezuela, Guyana, Colombia, Peru, and Ecuador and they are already classified as ‘endangered’ due to human threats. These dangers, including hunting them to use as fishing bait, entanglement in fishing nets, mercury poisoning from gold mining, and habitat destruction, are driving their populations to decline. With the future of these magnificent beings already hanging in the balance, the recent die-off and the likelihood of further dolphin deaths due to continuing drought and high water temperatures could be devastating and hasten extinction. River dolphin populations are slow to recover losses as they face multiple threats and are slow breeders – dolphin mothers only give birth to one baby at a time and do not get pregnant every year.

Scientists investigating the deaths of 155 dead river dolphins in the Amazon
We must protect river dolphins for their sake and our own. © Miguel Monteiro, Mamiraua Institute

The impact of the climate crisis extends beyond the river dolphins; human communities are suffering too. With rainfall hitting a four-decade low due to rising ocean temperatures, and changes in air flow preventing rain clouds from forming over the rainforest, the drought has left its mark on most of the main rivers.  The Amazon is home to approximately 40 million people, and for these communities, travelling by boat along these waterways is their lifeline, their only means of accessing fresh water and other essential supplies.  But the river water is now turning to mud, isolating indigenous communities and pushing them into a state of emergency. To make matters worse, the limited water supply they do have is being contaminated by the rotting bodies of the thousands of fish that have also succumbed to the intolerable temperatures.

Natutama Foundation carnival procession through the town to celebrate river dolphins
We're helping Indigenous communities become river dolphin guardians.

We’ve been at the forefront of river dolphin conservation for more than three decades. We work closely with local organisations and communities in Colombia, Bolivia, and Peru, and education is a big part of what we do. While the climate crisis rages on, we are working hard to reduce the human threats faced by these incredible dolphins to secure their future and ours. We need the Amazon, and the Amazon needs river dolphins. Keep an eye out for our next blog, where we'll tell you about the work we’re doing to support amazing communities in Colombia to coexist with and protect the unique dolphins who share their home.

Please help us today with a donation

If you are able to help, every gift, whether large or small, will help save river dolphins.