More than 100 dolphins died in the Brazilian Amazon rainforest in the past week due to a severe drought in the region, and many more could also expire soon if water temperatures remain high. The Mamiraua Institute, a research body of Brazil’s Ministry of Science, Technology and Innovation, said two more dead dolphins were found on Monday in the region of Tefe Lake, which is key for mammals and fish in that area. Thousands of fish have also died, according to local media. Experts believe the high temperatures of the waters are the most likely reason for the mortality in the region. Temperatures have exceeded 39 degrees Celsius (102 degrees Fahrenheit) in some parts. Miriam Mamontel has been working with Amazon dolphins for 30 years and says she has never seen anything like it, explaining that the deaths amount to 5 to 10% of the population of the two species of freshwater dolphin in Tefe Lake. Before the recent deaths, some 900 river dolphins and 500 Tucuxis inhabited the lake, Mamontel estimated. The state of Amazonas is facing an extreme drought that is affecting 60 out of the 62 cities in the state, leaving many communities isolated, as rivers are the main form of transportation. The Mamiraua Institute has warned that water temperatures may rise again in the next few days and could affect even more animals.