Many freshwater rivers or lakes have harmful algal and bacterial booms on their shores. A new study from a group of scientists suggests that these blooms could be early indicators of an ongoing ecological disaster that could lead to the worst mass extinction in Earth’s history.
Toxic microbial blooms thrived during the Great Dying, which was the most severe extinction in Earth’s history to date and was around 251 million years ago. During the Great Dying, it wiped out nearly 90 percent of the species on Earth. Now, because of human activity, these blooms are starting to thrive again because of the greenhouse gas emissions, deforestation, and soil loss.
The research, led by Chris Mays, a postdoctoral researcher, and palaeobotanist at the Swedish Museum of Natural History in Stockholm, found that the toxic algal and bacterial blooms during the Great Dying are similar to a recent microbial proliferation in modern lakes and rivers. Mays shared in an e-mail with Vice that although we are not in the same situation as the Great Dying yet, when “there was probably a six-fold increase in carbon dioxide” because “today carbon dioxide levels haven’t yet doubled since pre-industrial times.”
However, with the present steep increase in carbon dioxide, “we’re playing catch-up pretty well.”
In the study published in the journal “Nature Communications,” the scientists said that the repeated correlation of the booms with mass extinction events is a “disconcerting signal for future environmental change” and there is a lot of evidence to suggest that the Earth is currently in the midst of another mass extinction event.
The microbial blooms transform freshwater habitats into “dead zones” as they can choke out other species. Further, microbial blooms can delay the recovery of ecosystems by millions of years.
The team added in the published study, “The three main ingredients for this kind of toxic soup are accelerated greenhouse gas emissions, high temperatures, and abundant nutrients. During the EPE and other extreme warming events, volcanic eruptions provided the first two, while sudden deforestation caused the third. Specifically: when the trees were wiped out, the soils bled into the rivers and lakes, providing all the nutrients that the microbes would need.”
Now, humans are providing these three ingredients “in abundance” because carbon dioxide and warming are the “inevitable byproducts of burning fossil fuels for hundreds of years, and we’ve provided copious nutrients into our waterways, mostly from agriculture and logging. Together, this mix has led to a sharp increase in freshwater toxic blooms.” A large number of extinctions can result from releasing a lot of greenhouse gas in a short time.
In conclusion, Mays and his team said that unlike in the past, where the species suffered mass extinctions, there is an opportunity to prevent it. Toxic blooms can be prevented by keeping waterways clean and curbing greenhouse gas emissions.