Death by cyanobacteria-made microtoxins is not pleasant. The toxins damage the nervous system, especially anatoxin-a, also known as a Very Fast Death Factor.
As the global temperature increases, concerns about the range of these toxins are growing. For the first time, anatoxin-a has been found as far north as the polar regions, according to a new paper by Ewelina Chrapusta, a PhD candidate in molecular biology at Jagiellonian University, in Krakow, Poland, and her colleagues. They revealed that some cyanobacteria were capable of combining different types of toxins, in particular microcystins and anatoxin-a.
According to G. Zanchett and E.C. Oliveira-Filho, global climate change is anticipated to lead to the rapid development of hazardous cyanobacterial species with “increasing growth rate, dominance, persistence, geographical distribution, and activity”. In particular, glacier melt will provide more suitable habitats for cyanobacteria and lead to higher production of cyanobacterial toxins in the polar region.
Microcystins and anatoxin-a are produced by freshwater cyanobacteria. Their high toxicity makes them a serious threat to other organisms, including livestock and humans. According to J. Patockaa and L. Stredab, these toxins act extremely rapidly and could cause death in minutes or hours, depending on the dose.
In 1996, the first outbreak of cyanobacterial toxins poisoning occurred in Caruaru, Brazil, killing 76 patients from liver failure. Another episode happened in Brazil in 2000, which involved 2000 cases of stomach flu and 88 fatalities within roughly 40 days. These toxins are recognized as secondary metabolites. They allow the cyanobacteria to flourish under nutrient-rich conditions and reproduce exponentially.
Cyanobacteria are the most significant component of microbial and plant communities, especially in polar ecosystems, because they can provide microhabitats for other organisms. Specifically, they create a cohesive and diverse biocrusts on moist soils and in freshwater reservoirs of nutrient-poor habitats, especially glacial moraines. The biocrust serves as shelter for a variety of organisms, including rotifers, fungi, green algae, and viruses. Even though the ability of crust-forming cyanobacteria to produce toxins has been well demonstrated in temperate and tropical regions, the “ecological role of cyanotoxins in polar ecosystems is poorly understood,” according to Chrapusta.
As a result of global warming, increased frequency of cyanobacterial blooms pose severe threats to human health in communities worldwide, especially those that rely on glacier melt-water to live. Chronic exposure to cyanobacterial toxins in humans could increase the risk of organ damage, which may develop into cancer.
More research is needed to fully understand the extent to which rising global temperatures will influence cyanobacteria populations and their ability to produce toxins in the future. Moreover, specific species of cyanobacteria, which combine microcystins and anatoxin-a, need to be identified so that the distribution of such toxins could be monitored and projected accurately. In any case, the detection of anatoxin-a at high latitudes is a serious warning sign of possible dangers that may come in the future.