Blue-green algae are a type of bacteria that can make their own food through photosynthesis, just like plants. That is why they are green. This alga is typically known as cyanobacteria and lives in lakes, ponds, seawater, or even brackish water. Blue-green algae in lakes can form what are known as blooms. This phenomenon looks like green scum, foam, or a mat on the surface of the water.
This floating sludge is not only unsightly, but also tends to smell as the cyanobacteria die. Some forms of this algae are more toxic than others, and most cause irritation when in contact with the skin. Despite having negative effects, these algae could be responsible for the air on Earth today. Fossils dating back three billion years have been found and it is believed that algae were the main producers of oxygen long ago.
Many of the algae adhere to submerged rocks or plants in the lake. The more nutrient-rich a freshwater lake is, the more frequent the algae blooms. In addition to the amount of nutrients, the additional factors that determine the amount of this alga present in a lake are; pH, light and temperature. Most blooms are seen during the summer or early fall, as this time period is the perfect climate for the propagation of this green algae.
Algal blooms are often thought to be a nuisance when they occur in a lake that is used for recreational enjoyment. Swimming areas are closed when flowers are present and boating in these areas is also not desired. The abundance of this type of algae can definitely put a damper on the tourist industry in some areas.
Some benefits of blue-green algae include its use as a fertilizer, a food source, and in medical products. This type of algae is added to paddy fields and soil for fertilization. The algae add organic matter and nitrogen to the soil, which increases the productivity of the land and crops can be grown in otherwise barren soil. Soil erosion is also slowed by the addition of blue-green algae taken from the lakes, as they bind to soil particles.
Spirulina is a type of this algae that can be grown in freshwater and consumed by humans. It has a high protein and amino acid content. All the amino acids that humans need are contained in spirulina and the protein content is around 60%.
Poisonous varieties of blue-green algae are also found in the lakes. These are responsible for the death of cows and other farm animals. Some dogs have even been poisoned by blue-green algae in lakes. They often drink from the same lakes as many other wildlife and are not immune to the effects of algae.
Humans who have come into contact with the poisonous variety of blue-green algae have a variety of unpleasant symptoms; redness or sore throat, vomiting, diarrhea, itchy eyes, red skin around the eyes, nausea, and headache. Be very conscious of the water quality of any lake you enter to avoid this inconvenience.