What Are the Effects of Algae?

Under normal conditions, algae coexists with other aquatic life without a problem. Algae even has positive effects in ecosystems capable of maintaining a healthy level. Unclean water sometimes produces harmful levels of algae, however, capable of smothering and even poisoning aquatic life. Harmful amounts of algae even have the potential to hurt humans exposed to it.

Aquariums

• Most forms of algae have little to no health effects for the creatures in your aquarium, but algae hides the fish from view and has a negative impact on fish tank aesthetics. Blue-green algae, however, spreads rapidly over everything in the aquarium in slimy sheets, smothering and even killing off plant life. Keep unsightly algae levels in check by using algae-eating fish and manually cleaning the tank. Algae-eating fish have little effect on blue-green algae, however, since this algae appears as a result of poor water quality. Change the water and clean the tank to help reduce the effects of blue-green algae.

Marine Life

• In nature, algae plays a vital role in both freshwater and marine ecosystems, capturing sunlight to process into oxygen and providing food for several species of fish. Algae has a negative effect when it gathers in excess, though, a phenomenon referred to as "harmful algal blooms." An unnaturally high abundance of algae blocks sunlight from reaching underwater grasses, interferes with organisms that filter water to obtain food, and sometimes actually consumes oxygen, resulting in fish deaths. Some species of algae even produce toxins capable of poisoning aquatic life.

Human Health

• Algae blooms pose many potential dangers to humans. Reports suggest that Pfiesteria piscicida, a type of algae living in estuaries near dead fish, may cause headaches, skin rashes and eye irritation. Harmful marine algae, particularly those linked to red tides, kill fish and may cause neurological and gastrointestinal symptoms in humans who eat poisoned fish. Blue-green algae produces toxins capable of tainting drinking and recreational water and may cause gastroenteritis, skin irritation, allergic reactions and liver damage. On the other hand, some evidence supports the use of blue-green algae supplements for the treatment of precancerous mouth lesions, but only if completely free from additional contaminants. Even so, the use of blue-green algae as treatment remains controversial.

Economic Effects

• Damage caused by harmful algal blooms and the management of this algae often have significant economic impacts on communities and companies that rely on the infected bodies of water. In 2006, Hoagland and Scatasta reported that the economic effects of harmful algae totaled $82 million per year. Costs came from algae's impact on commercial fisheries, public heath and illness concerns, the impact on recreation and tourism and the labor of coastal monitoring and management.