What is Anabaena? Everything You Need to Know About This Common Threat
Harmful algal blooms can be made up of many different types of blue green algae. One such type is Anabaena. This filamentous alga can pose a significant threat to water quality and are an important species to be aware of. This short article will cover the basics of Anabaena including identification, ecology, threats to water quality, and treatment methods.
Identification and Ecology
Anabaena is the second-most commonly report blue green algae after Microcystis. It is also quite a unique looking alga. It is a filamentous algae made up of many individual, spherical or barrel-shaped cells. The size and shape of the cells as well as the length of the filaments can vary depending on the species. Anabaena filaments can, occasionally, consist of three types of cells: vegetative, heterocytes, and akinetes.
Vegetative cells are the uniform green cells that are the actual Anabaena cells. Heterocytes are the larger, round, and usually clear-looking cells where nitrogen fixation takes place. Akinetes are very large, sometimes round, sometimes ovoid cells that are dormant cells. The thick-walled dormant akinete cells split off from the rest of the filament under stressful conditions, allowing Anabaena to persist through harsh conditions.
Anabaena’s ability to produce heterocytes allows it to fix atmospheric nitrogen for use in the cell. Nitrogen fixation gives Anabaena big advantage over other types of algae because Anabaena does not have to rely on nitrogen in the water to persist. Most other types of algae need nitrogen to be dissolved in water in one of a handful of forms (nitrate, nitrite, ammonium, etc.). Because of this, Anabaena can be found in aquatic systems with relatively low amounts of nitrogen. However, it is widely believed that Anabaena can not form blooms if relying on nitrogen fixation. This process consumes a lot of the cell’s energy, meaning there is not enough for cell replication.
Anabaena Toxins
Anabaena can produce two common toxins: anatoxin and microcystin. Microcystin is a potent liver toxin that can cause partial or complete liver failure depending on the amount of toxin consumed. Microcystin events have been well documented, and the toxin is often monitored in areas with frequent blue green algae issues. For more information of, check out our article detailing everything about microcystin.
Anatoxin is an acute neurotoxin that can cause tremors, staggering, gasping, paralysis, or death depending on the dose. The safe level of anatoxin in drinking water is listed as 0.1 ppb according to the Minnesota Department of Health.
Cases of anatoxin poisoning have been reported multiple times in pets. Dogs commonly swim in contaminated water or consume parts of dead fish that wash ashore. Most recently, a flat-coated retriever died within 45 minutes of licking a dead fish that washed up on an English lake shore. An autopsy and toxicological test later confirmed that the dog had lethal amounts of anatoxin in its stomach and urine.
As with most toxins produced by blue green algae there is very little understanding as to what causes Anabeana to produce anatoxin or microcystin. Not all Anabaena cells can produce toxins, and even the ones that can may not be producing toxins when the algae is identified.
As with all blue green algae, if you notice a bloom, keep you, family, neighbors, pets, and livestock away from the water. If the bloom is occurring in a public water body, contact your state’s environmental protection office or fish and wildlife officials, or report the bloom using the Center for Disease Control’s website.
Treating Anabaena Blooms
We have an entire article dedicated to treating water bodies affected by blue green algae. In short, the main options include nutrient reduction, chemical controls, physical controls, and biological controls. Each strategy has its pros and cons and some strategies are rapid and short-sighted while others are geared towards preventing future blooms.
The key factor in treating your system for blue green algae is to know your system and how feasible and effective each treatment strategy is. It is important to consider consulting resource professionals and developing a remediation plan that works for your particular system.
Conclusions
Anabaena are a very common and potentially harmful group of blue green algae that have unique adaptations to persist in all sorts of conditions. Anabaena can use atmospheric nitrogen for cell processes and produce dormant cells to ensure future survival in case things go south for them. Lastly, Anabaena can produce several types of very harmful toxins and every precaution should be taken if it is identified in a lake, pond, or river. We hope you found this helpful in understanding another commonly seen blue green algae.