Severe drought and soaring temperatures are causing lakes and rivers in the Amazon to reach dangerously high temperatures, threatening species like the Amazon river dolphin, according to a recent study’s preprint. In 2023, the Amazon experienced its worst drought in recorded history, coupled with the hottest dry season on record. The extreme climate caused the surface area of Brazil’s Tefé Lake to shrink by approximately 75%, with vast sections of the lake reduced to less than 1 meter (3.3 feet) in depth. As air temperatures peaked at 39.1° Celsius (102° Fahrenheit), the little water that remained in the lake quickly overheated. The average surface water temperature for tropical lakes is around 30°C (86°F), but in 2023, Tefé Lake reached 41°C (105°F). Using advanced hydrodynamic modeling, the researchers found that the entire water column, up to 2 meters (6.6 feet) deep, reached 40°C (104°F), leaving no refuge for animals seeking cooler temperatures. The study focused on Tefé Lake because of the mortality event observed the same year, 2023, when more than 200 endangered Amazon river dolphins (Inia geoffrensis) and tucuxi dolphins (Sotalia fluviatilis) perished. The researchers say the deaths were likely caused by the extreme water temperatures that year. The scientists caution that with ongoing climate change, temperatures that exceed heat tolerances for aquatic species will become more common. Tefé Lake is not an anomaly. Five out of the 10 lakes examined in the study had exceptionally high daytime temperatures. The findings reflect a broader, long-term warming trend in Amazonian waters.…This article was originally published on Mongabay
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