Toxic Algae Blooms Are on the Rise

Toxic algae bloom in Lake Erie, 2011 Credit: Jesse Allen and Robert Simmon, NASA Earth Observatory via WIkimedia Commons. Public domain

Cyanobacteria are one of nature’s great opportunists. Every summer, these primitive organisms erupt in vast blooms in ponds and lakes, soaking up the sun’s energy. Feeding on nitrogen and phosphorus, these bacteria colonies multiply and eventually die, releasing toxic waste products called cyanotoxins that accumulate during their growth.
These events are known as harmful algal blooms, because the pose a threat to public health. Cyanotoxins are unstable and change rapidly, making detection difficult. Some harm the nervous system. Others, known as hepatotoxins, can severely damage the liver and kidney. HABs can occur in marine or freshwater environments, closing fisheries, beaches and even entire lakes.
Evidence is mounting that HABs are increasing in both frequency andintensity. Drought conditions brought on by climate change can depress lake levels, concentrating nutrient-rich agricultural runoff in areas of low turbidity. Torrential rainfall can also trigger a sudden influx of agricultural nutrients, as occurred in Florida’s Lake Okeechobee this year, where a HAB flowed seaward, forcing beaches to close. Blooms containing the most common type of harmful cyanotoxin—microcystin—struck theMormon Reservoir in Idaho, several lakes in Montgomery County in Maryland and Bonney Lake in Washington. In the latter case, a dozen swimmers became ill after swimming in the HAB.

Read more: http://blogs.scientificamerican.com/guest-blog/toxic-algae-blooms-are-on-the-rise/