Extreme Drought Leads to First Record of Euglena sanguinea Ehrenberg Blooms in Amazon Lakes

The climate extreme is imposing several threats to Amazonian ecosystems. In 2023, an extreme drought in the Amazon basin and the impacts were measured in the Tefé and Coari lakes, including unprecedented river dolphin mortality and phytoplankton blooms. This study presents the first recorded bloom of Euglena sanguinea in the Amazon, to our knowledge the first record of a phytoplankton bloom directly associated with climate change in the region. We examined the morphology and molecular identification of this species, and the potential environmental impact of its toxins. The analysis involved qualitative and quantitative sampling, microscopic observation, PCR-based molecular identification, and toxin detection. Our findings highlight the need for improving ongoing monitoring of phytoplankton dynamics in response to climate change in the basin, as these events can have serious consequences for both the environment and the local populations.