STORY: One hundred and twenty lifeless river dolphins were recently found floating on a tributary of Brazil’s Amazon River.And researchers say there could be more deaths of this unique freshwater species to follow, as they suspect severe drought and heat are responsible. Experts say low river levels have caused a spike in water temperature. And in some sections, the water is too warm for the dolphins to thrive.Researcher Ayan Fleischmann has been monitoring changes in and around Lake Tefe:"The water temperature was very high on the day of the deaths in certain moments, exceeding 102 degrees Fahrenheit, which is an extremely high value. The average here in our region in Lake Tefe is between 84 to 87 Fahrenheit, for this time of the year it’s an extremely high value and it is certainly related to the deaths.” As scientists perform autopsies on the deceased mammals, veterinarians and aquatic mammal experts have rushed to rescue dolphins that are still alive in Lake Tefe, but they cannot be moved to cooler river waters until researchers rule out bacterial infection as the cause. But time is of the essence as these pink and gray river dolphins were already on a red list of threatened species.