Bursts of phytoplankton are appearing in oceans, seas, gulfs, canals—and increasingly in lakes.
The Operational Land Imager (OLI) on the Landsat 8 satellite captured this image of an algal bloom on Lake Villarrica in Chile on May 2, 2023. Ground-based observations and analysis of additional satellite images suggest that cyanobacteria make up the light blue-green swirls in the natural-color image.
Lake Villarrica, which sits downslope of the volcano of the same name, attracts visitors with its scenic beaches and recreational opportunities. The lake is flanked by small cities and resort areas on its southern shore, with agricultural areas further afield. Runoff from development and agriculture carries nutrients such as nitrogen and phosphorous into the lake. When populations of microscopic cyanobacteria spike in response, the blooms often show up in satellite images.
Image Credit: NASA Earth Observatory image by Wanmei Liang, using Landsat data from the U.S. Geological Survey