Why are some lakes full of algae and thick plants?
Plants naturally grow in and around lakes, but sometimes lakes and ponds can get an overgrowth of plants, algae, or bacteria. In many cases, humans are responsible. Chemicals that are used on lawns and in agriculture (like nitrogen and potassium) wash into our water systems. Once there, plants and algae have a feast on this “food”.
Sometimes overgrowths of cyanobacteria (called “blooms”) can make the water scummy and turn it a blue-green color (or other colors). Cyanobacteria produce compounds that impact the taste and odor of water, make fish unpalatable, and even produce toxins that affect human health. Scientists are still studying the causes of these blooms.
Learn more: USGS Water Science School - Why are some lakes full of algae?
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Cyanobacteria - Scytonema (blue green algae)
Microscopic view of blue green algae sample. Some algae produce toxins that threaten the health and safety of living things that come in direct contact. Cyanobacteria - Scytonema (blue green algae)
Cyanobacteria - Phormidium (blue green algae)
Microscopic view of blue green algae sample. Some algae produce toxins that threaten the health and safety of living things that come in direct contact. Cyanobacteria - Phormidium (blue green algae)
Landsat Image of Cyanobacteria
Images from Landsat, and other satellites, help locate the blue-green swirls associated with cyanobacteria. Photograph credit: NASA.
Aerial View of Lake Okeechobee
An aerial view of Lake Okeechobee in Florida shows an algal bloom. A third of all lakes studied by the USGS contained toxins produced by similar blooms. Photograph credit: Nicholas Aumen, USGS.
Collecting a sample from a cyanobacterial bloom
USGS scientist collecting a sample from a cyanobacterial bloom from Milford Lake, KS; Sept. 2, 2011.
Algal Toxin Photo
Creek filled with Algal Toxins is surrounded by plant life on both banks. Trees line the background.
Cyanobacteria - Nostoc (blue green algae)
Microscopic view of blue green algae sample. Some algae produce toxins that threaten the health and safety of living things that come in direct contact. Cyanobacteria - Nostoc (blue green algae)
Cyanobacteria - Dolichospermum (blue green algae)
Microscopic view of blue green algae sample. Some algae produce toxins that threaten the health and safety of living things that come in direct contact. Cyanobacteria - Dolichospermum (blue green algae)
Harmful Algal Bloom (HAB) in a stream
Algal Bloom on Upper Klamath Lake
A view of an algal bloom in Upper Klamath Lake from field sampling boat.