Amazon Lakes Have Turned Hotter Than Spa Baths, Causing Mass Deaths of Pink Dolphins— New Study Says

Another stunning species is headed towards its doom. The extreme climatic conditions of the Amazonian lakes have become a slow poison for their inhabitants. A recent study has discovered that the extreme warming of Amazon lakes is resulting in mass die-offs of pink dolphins. No rainfall and high heat have resulted in decreased water levels that are as hot as a sauna bath. Some of the lakes have exceeded 40°C or 104°F, a temperature not suitable for the river dolphins and fish. According to the study published in the journal Science, the temperature of  Lake Tefé has reached 41°C or 105.8°F. “We couldn’t even put our fingers in the water. It was really hot, not just in the top bit, but right down to the bottom,” said lead researcher Ayan Fleischmann, from the Mamirauá Institute for Sustainable Development.

The researchers admitted that they pulled their fingers out as soon as they touched the water because the temperature was "unbearable." It's impossible for a species suitable for a temperate environment to endure heat at such high intensity. In recent years, frequent droughts, alongside dam construction and fishing, have pushed the dolphin species to the verge of extinction, as per National Geographic. The largest freshwater dolphins are currently classified as endangered. In September 2023, the deceased bodies of about 200 pink dolphins washed up on the shores over a period of six weeks, as reported by The Guardian. “It was completely surreal and really scary," Fleischmann admitted.

The shocking scene was a wake-up call for the researchers who began investigating other lakes and water bodies across the Amazon region. Researchers investigated lake temperature during the Amazonian drought in 2023. A follow-up research was conducted a year later, which captured record-breaking high heat and low water levels. The Lake Tefé, on average, would reach 30°C or 86°F during the peak of summer, but in 2024, it reached 40°C (104°F).

Moreover, the droughts are drying up and shrinking the lakes. Last year's research showed that Lake Tefé lost about 75% of its surface area and Lake Badajós shrank by 90%. Adrian Barnett, senior lecturer in behavioural ecology at the University of Greenwich, wasn't a part of the research but was amazed by the impacts of climate change. “The paper shows the extraordinary impacts climate change is having, even on such huge ecosystems as the Amazon, and that these are not restricted to the forests, but the aquatic realm as well," he said.

Barnett also reacted to the drastic increase in the lake temperature only within the span of a year. “A 10°C [50°F] increase in water temperature is unparalleled. The volume of energy needed to achieve this in such huge volumes of water is jaw-dropping," he added. Low water levels are usually good for dolphins, fish, and manatees to reproduce. The calm environment likely makes it easier for the freshwater creatures to find food and breed. Barnett believes that 2023 was likely disastrous for reproduction. Along with the reduced water level, the animals had to endure high temperatures. “If this happens repeatedly, then their populations and those of the species that are connected to them ecologically will decline severely,” the researcher warned.