Even in the dry season, the Amazon river is so vast that I can鈥檛 make out the other side with my binoculars. We have travelled 2 hours downriver from the Colombian town of Puerto Nari帽o, searching for a dead dolphin reported by a fisherman. We only spot the carcass on the riverbank thanks to the vultures perched on top.
The pink river dolphin (Inia geoffrensis) is symbolic of the biodiversity of the Amazon rainforest and is sacred to many Indigenous communities, yet its numbers are declining , raising fears it could eventually disappear.
Jimena Valderrama, a vet working with the Omacha Foundation, inspects the 2.5-metre-long carcass to learn what killed it, but there is no immediately obvious cause. 鈥淲hen a species is endangered, the loss of every individual is incredibly important for their survival, which is why we fight so hard to save each one,鈥� she says.
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The dolphins face many threats. The fish populations they feed on are dwindling, an illegal mining boom is and fishers kill
them for their meat, which is used as bait for catching piracatinga, a聽kind of catfish.
On top of all that, the Amazon is聽currently experiencing its most intense dry season in more than a聽decade. Last week, the Amazon鈥檚 second largest tributary, the Rio聽Negro in Brazil, reached its . There are growing signs that the extreme temperatures are killing off local wildlife, and this could be聽a glimpse of what is to come from聽climate change.
The dolphin carcass we found on the Colombian-Peruvian border follows reports of large numbers of dead fish in the surrounding rivers and lakes. Even聽more concerningly, 153聽dolphins have been found since late September.
Extremely low river levels exacerbated already high temperatures and , say local researchers. Water temperature readings at Lake Tef茅 which is 9掳C (16掳F) above average for this time of year.
The Omacha team in Colombia usually finds one dead dolphin a year, but they have already found two this month, says Valderrama. Both probably died after getting entangled in fishing nets.
As climate change intensifies, these incidents will become more common, she says. 鈥淕enerally, when the rivers are low, there are more nets set in a smaller amount of water, leading to more dolphin mortality.鈥� Declining fish stocks could also increase conflict with fishers, who occasionally kill dolphins for stealing their catch.
Dolphins are an umbrella species, meaning their success influences the fate of many other species in the ecosystem, so it makes sense to focus conservation efforts on them, says Silvia Vejarano, a biologist and conservation specialist at WWF, which is supporting Omacha.
鈥淭he dolphins help make otherwise intangible problems, that are threats not only to dolphins but also the millions of people who inhabit the Amazon, visible,鈥� she says.
On 24 October, Colombia, Brazil and nine other countries found across Asia and South America with solutions including sustainable fisheries, better managed protected areas and reducing pollution.
As we travel on the Loretoyacu river, a tributary of the Amazon, we must abandon the boat and walk along the banks because the聽water is too shallow after two months of unusually low rainfall.
For us, it is an inconvenience and we get caught in a tropical downpour. But for many who inhabit the Amazon rainforest, it聽is a serious threat. In recent months, people have been cut off聽from food supplies, fuel and聽hospitals. In Brazil, the government is distributing aid聽by聽helicopter to some Indigenous communities.
鈥淭he drought has been really worrying as we rely on rainwater to drink,鈥� says Gentil Gomez, a community leader for the Ticuna Indigenous community, who live聽off the fish in Lake Tarapoto, Colombia. 鈥淚t鈥檚 also hard to get to聽Puerto Nari帽o to buy supplies, and we鈥檝e seen different species of聽fish die in our rivers.鈥�
A recent shift from the La聽Ni帽a聽weather phenomenon to聽El Ni帽o is playing a role in the abnormal weather. But a study by聽World Weather Attribution concluded that without the impact聽of humans, the recent record temperatures across South聽America would be
Precisely how climate change is affecting wildlife across the huge range of the Amazon rainforest is poorly understood, says Vejarano. 鈥淲e do not really know yet all the consequences that warming temperatures have for all of the fauna, microorganisms and plankton that regulate the ecosystem, but we are increasingly seeing the consequences in the dolphins. And they are just the tip of the iceberg.鈥�
