Mass extinctions in the ocean may have been caused by the first land plants to evolve penetrating root systems around 400 million years ago.
The expansion of plants onto terra firma was a major event on Earth. The consequences for our oceans might have been just as profound according to researchers from Indiana University–Purdue University Indianapolis.
The marine environment experienced many mass extinction events during theDevonian Period. Up to 60 percent of all genera in the ocean were wiped out by a particularly destructive event at the end of this period.
The root cause of these losses is thought to be trees.
When plant life moved away from water sources, they dug even deeper for new sources of nutrition. Their roots would have begun to pull the minerals from the underground.
Once the tree is dead, the nutrients within it can be easily dissolved into the water.
As root systems grew more complex, more and more phosphorus would have been dumped into the marine environment.
The destruction of these nutrients can be seen in a new timelines. The data is derived from the chemical analysis of stones from ancient lake beds and coastlines.
Gabriel Filippelli is an IUPUI earth scientist.
There would have been catastrophic mass extinction events due to the rapid and destructive blooms.
Scientists have suspected tree roots of being involved in mass extinctions in the past, but this study is the first to calculate the magnitude and timing of the delivery of phosphorus from land to water.
Most cases suggest that there was a large and rapid change in the environment of the lake during the Devonian.
The elevated nitrogen levels in the ocean line up with extinction events and suggest that the crisis was caused by the elevated nitrogen levels.
The authors say that the peaks of exportation did not correlate with time or magnitude at each site. They say that the colonization of land by plants was staggered geographically, peaking at different times in different parts of Europe.
The marine extinction events that lasted many millions of years were caused by the rapid decline in the amount of phosphorus on land. Although the precise processes behind the plant growth and decay seem to have varied, an overall trend seems apparent. Researchers found that when there was less water, the amount of phosphorus delivered to the lakes shot up.
When trees first arrived on the scene, they were much more destructive than they are today. The deeper the soil is, the easier it is for mineral-bound phosphorus to hide beyond the reach of roots.
What is happening today is similar to what happened hundreds of million of years ago.
The changes in atmospheric carbon dioxide and oxygen back then were due to the slow advancement of plant life as opposed to rapid changes through human activity.
Tree roots are not required to make it out to sea. It's triggering dead zones of low oxygen in many important marine and lake environments because it's pumped there by us.
"New insights into the catastrophic results of natural events in the ancient world may serve as a warning about the consequences of similar conditions arising from human activity today."
The study was published in a journal.
All Rights Reserved © 2024
