NEW DELHI: More than hundred dolphins have died in a tributary of Amazon river last week in Brazil. According to experts, deaths may have been caused by severe drought and rising heat and many more could die soon if water temperatures remain high.

Media reports said that at least 70 of the remains were found floating on Thursday when the temperature of Lake Tefe's water reached 39 degrees Celsius which is 10 degrees higher than the usual average for this time of the year. 

Meanwhile, Brazilian government’s Chico Mendes Institute for Biodiversity Conservation, which manages conservation areas, said last week it had sent teams of veterinarians and aquatic mammal experts to investigate the deaths.

Earlier on Friday, Amazonas Governor Wilson Lima declared a state of emergency due to the drought.