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The Effects of Algal Blooms

Algal blooms are caused by the rapid increase of cyanobacteria in an aquatic environment. Blooms occur when conditions are just right, including an ideal water temperature and the presence of fertilizers and phosphates. Algal blooms can be a nuisance when they occur in your pond or lake, and they can be difficult to get rid of.

Water Discoloration
- The clearest effect of an algal bloom is the discoloration of the water. The surface will turn a shade of green, depending on the species and concentration of the bacteria, or it could turn aqua or bluish. In fact, cyanobacteria was named for the turquoise hue it produces. In salt water environments, the phenomenon known as red tide is a form of algal bloom, where the phytoplankton Alexandrium and Karenia turn the surf a tone of dark red or brown.
Toxins
- Some algal blooms give off harmful toxins, including saxitoxins, brevetoxins, domoic acid, okadaic acid, azaspiracids, ciguatoxins and microcystins. These toxins can harm or kill fish, water fowl and aquatic mammals, and can work their way up the food chain by poisoning those that contact or eat an affected creature. In humans, these toxins can cause amnesia, cramps, nausea, paralysis and even death in extreme circumstances, according to SeaWeb. When algae makes its way to fish farms, the effects can be swift and gruesome, as fish populations can easily be decimated.
Nontoxic Impact
- Not all forms of algal blooms are toxic, but they can have adverse effects on the environment. Some forms of algae can stick to the gills of fish, leading to their death. Algae can also deprive water of oxygen, again killing fish and marine life. The financial ramifications of algal blooms can be costly as well; the Pacific northwest has seen millions of dollars worth of salmon killed in the 1990s from algal blooms. Beach-goers can also take their tourist dollars to uninfected areas, taking away from coastal towns' tourist revenues.
Mysteries
- There is no way to visually detect whether an algal bloom is harmful or not, and testing can take a long time to complete. Algae cells can apparently disappear in the evening hours, though what actually happens is they sink to the bottom in a state of hibernation until the sun comes out the next day, when they rise back to the surface. Some blooms are difficult to study due to their short life, and it is still unknown what causes blooms to release their toxins, claims the Minnesota Poison Control Agency.

Nature