A new research study proves freshwater biodiversity is on its way to a mass extinction event less than one hundred years from now, which even millions of years will not heal.
Hundreds of millions of years of history of the snail/gastropod family has revealed some chilling clues about how fast mass extinctions are already happening on the planet. Photo: Image by azeret33 from Pixabay
Thanks to human clumsiness, greed, and self-centered abuse of nature, the sixth mass extinction event on Earth is accelerating on a broader basis and faster than ever imagined. Even before humanity snuffs out the last of all life, it will leave in its wake the wiping out of roughly one-third of all freshwater species living on the planet by 2120.
That is the conclusion of a group of researchers in a new paper published on May 21, 2021, in the peer-reviewed journal Communications Earth & Environment. The paper was written by lead author Thomas A. Neubauer of the Department of Animal Ecology and Systematics, Justus Liebig University, Giessen, Germany, and of the Naturalis Biodiversity Center, Leiden, The Netherlands.
There is a saying that water is the source of most life on the planet. Between oceans and freshwater systems alike, some 70% of the world’s food chains link back to the waters around us in a disproportionate manner. So while we humans may live on the Earth’s surface, we too depend on the biodiversity of life in these waters for the survival not just of our species but also of those around us.
Freshwater systems, including rivers, lakes and wetlands, are often ignored by the general public as little other than a place to extract fish for food or to dump treated waste. This comes from a misunderstanding of the importance of the ecosystems residing there, mostly because with freshwater covering just 1% of the world’s surface it is easy to think it must not be that critical to the planet’s health.
That assumption is belied by a first reality that such freshwater systems account for 10% of the total diversity on the planet. It is also a fact that though just 1% of all aquatic habitats are freshwater ones, 51% of all known fish species are found in freshwater.
Why that biodiversity is so rich, both in fish and other species that can only exist in freshwater, has to do with the varying ecosystems in and around the freshwater regions of the world.
As was covered earlier this year in The World’s Forgotten Fishes, a report published by the World Wide Fund for Nature (WWF) and 15 other conservation groups, that richness has taken a big hit thanks to the same sort of human abuse that brought us global warming thanks to accelerated burning of fossil fuels.
While global heating is partially responsible for the damage to freshwater systems’ biodiversity, another problem is the widespread pollution which has been pouring into freshwater arteries everywhere. Industrial waste, toxic sewage, and runoff from overused agricultural fertilizers have flowed freely into lakes and rivers for centuries.
As detailed in the WWF report, one impact of this abuse has been that total populations of freshwater have declined by over 75% in just 50 years.
The current study builds on this study, this time by investigating what happened and is happening to 3,000 living and fossilized snail species. By focusing on this classification of species, the researchers were able to look at far more than just the last fifty years of the WWF report. They could trace what happened to snails over almost 200 million years of data.
The reason for choosing snails (gastropods) to look at both extinction rates is because, as the researches wrote, “They are among the most diverse groups of animals in freshwater ecosystems today and have one of the best-preserved fossil records.”
“They inhabit nearly all freshwater habitats worldwide and have evolved different lifestyles and reproductive strategies,” the authors continued. “Moreover, current threats and their response to climate change are well understood and representative of the general threats facing freshwater biodiversity as a whole.”
Using this array of species as their focus, then, they looked in detail at the Cretaceous-Paleogene mass extinction event. That was the one which happened many millions of years ago and which is thought to have been triggered by an asteroid striking the earth’s surface. Though many think of this as an instantaneous extinction event, the period of extinction lasted 5.4 million years before all damage was complete, according to the scientists.
The new study compared this extinction rate to the current ones for the snail species they were investigating. They also looked at recovery times needed to rebuild biodiversity from that much earlier era to present day projections. What they found was far more serious than they had expected.
They discovered that modern extinction rates for European freshwater gastropods are “three orders of magnitude higher than even [the latest] revised estimates for the Cretaceous-Paleogene extinction.”
That extinction rate projects out to a loss of roughly one-third of all snail species by just under one hundred years from now. It also happens to line up precisely with the WWF study, which shows 76% of migratory freshwater fish populations disappeared since 1970, and one-third of those remaining will be gone by the end of this century.
What this says is we are currently in the midst of a mass extinction event which is killing off species at a rate far faster than any previously known period in the history of Earth.
Perhaps more chilling still is about how long the planet may take to rebuild its species biodiversity after the current extinction event has run its course. As the authors write, “species richness recovered c. 7-8 [million years] later to Late Cretaceous levels.”
In short, for all practical purposes, the planet is about to hit a hard restart for virtually all life on the planet, beginning for at least one-third of all species just 100 years away. In a few hundred years, most of the remaining species will be gone.
We humans will likely be gone with them, perhaps never to return in similar form.
Less we think we can do something to reverse the environmental damage humanity has laid in place to cause this new mass extinction, study lead author Thomas Neubauer has important cautionary words we all need to listen to carefully.
“Even if our impact on the world’s biota stops today, the extinction rate will likely stay high for an extended period of time,” Neubauer said in a statement connected with the release of the paper. “Considering that the current biodiversity crisis advances much faster than the mass extinction event 66 million years ago, the recovery period may be even longer. Despite our short existence on Earth, we have assured that the effects of our actions will outlast us by millions of years.”