Dangerous algae containing a toxin believed to be linked to neurodegenerative disorders such as Alzheimer's has been proliferating in lakes across North America and Europe.
A recent study showed organisms known as blue-green algae have multiplied much more quickly in these bodies of water than any other algae over the past two centuries, and have spiked dramatically since the mid-20th century, McGill University reported. The new study provides the first continental-scale look at historical changes in levels of cyanobacteria, which can contaminate drinking water sources with its dangerous toxins.
"We found that cyanobacterial populations have expanded really strongly in many lakes since the advent of industrial fertilizers and rapid urban growth," said Zofia Taranu, who led the study as a PhD candidate in McGill's Department of Biology. "While we already knew that cyanobacteria prefer warm and nutrient-rich conditions, our study is also the first to show that the effect of nutrients, such as phosphorus and nitrogen, overwhelm those of global warming."
The findings showed increases in cyanobacteria in agriculturally developed watersheds was in line with past predictions, but also in unexpectedly remote alpine lakes. The researchers believe these increases in cyanobacteria is largely linked to warmer temperatures and nutrient loading from atmospheric source.
Even though these algae do not always synthesize toxins, studies have shown the most prevalent indicator of toxin concentration is total abundance of cyanobacteria. The most common symptoms of acute exposure to these algae toxins is "skin rash or irritation, gastroenteritis and respiratory distress." Chronic low-dose exposure can also result in liver tumors or endocrine disruptions, recent studies have even shown a link between cyanotoxin and neurodegenerative diseases.
"Our work shows that we need to work harder as a society to reduce nutrient discharges to surface waters," said Irene Gregory-Eaves, an associate professor of biology at McGill and co-author of the study. "Because diffuse nutrient loading (as opposed to end-of-pipe effluent) is the main issue, we need to build collaborations to tackle this complex problem. For example, partnerships among freshwater scientists and farmers are starting to happen, and more of this needs to take place, so that we can strike a balance between maximizing crop yields and minimizing excess fertilizer application."
The findings were published in a recent edition of the journal Ecology Letters.
