The waters of Lago d’Averno, a volcanic crater lake in Southern Italy, have transformed since early March to become a murky blood-red due to an overgrowth of algae. The European Space Agency’s Sentinel-2 satellite and local photographers have captured the lake’s eerie new vibe.
Scientists observing the lake believe that the drastic change in color is due to a seasonal algae bloom and the accumulation of nutrients in the lake’s water, according to local newspaper Corriere del Mezzogiorno. Nutrients like phosphorous and nitrogen occur naturally and can be found in many lakes.
The water quality could affect the many different species that live in or near the lake. Some research has found that algal blooms can weaken the immune systems of animals living around them. Mass fish deaths are also linked to algal blooms, which can suck up oxygen from the water.
Microscopic organisms called cyanobacteria gain energy through photosynthesis and are known to cause red waters around the world. The CDC warns people to stay away from algal blooms, which can produce toxic gases. Toxins from blue-green algae may be able to go airborne and potentially harm people and pets, research has suggested.
Here’s what the lake usually looks like. The beautiful area is known for its biodiversity and is a protected zone within Italy’s Regional Park of Campi Flegrei.