At least 125 river dolphins have been found dead in the Brazilian Amazon Rainforest region. This comes during a historic drought and period of record high temperatures, with some water temperatures exceeding 102 degrees fahrenheit (NPR). Experts say that if these high temperatures continue, many more of the endangered dolphins will soon die.
Amazon River dolphins are endangered, despite their reputation as a resilient species. Over 125 of the 1,400 river dolphins that live in the Amazon River have been found floating or beached on the shores of Lake Tefe (NYT, NPR respectively).
The Mamiraua Institute, a research organization funded by the Brazilian Ministry of Science, is leading the investigation into the cause of these dolphin deaths. While scientists are investigating other causes, including possible diseases or polluted water, the institute has linked the deaths to the drought and high temperatures in the region. This is because the drought makes the river more shallow, which causes the water to reach dangerously high temperatures, harming the dolphin population.
“You see the water covered with carcasses,” said Miriam Marmontel, a researcher with the Mamirauá Institute (NYT). At least 70 of the carcasses surfaced on Thursday, October 5th, when the temperature of Lake Tefé’s water reached 39 degrees Celsius (102 degrees Fahrenheit), which is over 10 degrees higher than the average for this time of the year. On Sunday, October 8th, the temperatures remained high at 38 degrees Celsius, or 100 degrees Fahrenheit (Reuters).
The cause of this extreme weather is potentially linked to climate change and the El Niño phenomenon, a climate pattern that describes the unusual warming of surface waters in the eastern equatorial Pacific Ocean.
The institute has been recovering carcasses since September 23rd. Local media has also reported that thousands of fish have died and washed up along with the dolphins, due to lack of oxygen in the water.
In addition to the negative impact on the wildlife, the community around the Tefe River has also been suffering during this drought. Ayan Fleischmann, the Geospatial coordinator at the Mamirauá Institute, said the drought has had a major impact on the riverside communities in the Amazon region. “Many communities are becoming isolated, without access to good quality water, without access to the river, which is their main means of transportation,” he said (Smithsonian Magazine).
