The carcasses of 120 river dolphins have been found floating in a tributary of the Amazon River over the last week in circumstances that experts suspect were caused by severe drought and heat, Reuters reported today.
It said low river levels during a severe drought have heated water in stretches to temperatures that are intolerable for the dolphins, researchers believe.
Thousands of fish have died recently on Amazon rivers due to a lack of oxygen in the water.
The Amazon river dolphins, many of a striking pink color, are a unique freshwater species found only in the rivers of South America and are one of a handful of freshwater dolphin species left in the world. Slow reproductive cycles make their populations especially vulnerable to threats.
Amid the stench of decomposing dolphins, biologists and other experts in white personal protective clothing and masks continued on Monday to recover the dead mammals from a lake and conduct autopsies on the carcasses to determine the cause of death.
The scientists do not know with certainty that drought and heat are to blame for the spike in dolphin mortality. They are working to rule out other causes, such as a bacterial infection that could have killed the dolphins on a lake formed by the River Tefé before it runs into the Amazon.
At least 70 of the carcasses surfaced on Thursday when the temperature of Lake Tefé’s water reached 39 degrees Celsius (102 degrees Fahrenheit), more than 10 degrees higher than the average for this time of the year.
