A 300 million-year-old specimen warns you that it will take 23 million years to recover from a coral reef collapse
In the late Devonian period 370 million years ago, South China was still an ocean, and the blue water gently beat the beach. Not far from the coastline, there was a system of large and small reefs.
Diving into the water is like being in the world of Finding Nemo. Amidst clusters of dancing corals and stratozoa reefs, various marine creatures shuttle and live endlessly...
However, this unprecedentedly prosperous biological reef soon ushered in its extinction: as the global climate became cold, the sea level dropped, and a large number of biological reefs emerged from the water surface and died quickly, and this was only the beginning of the Devonian biological extinction. .
So, how long did it take for these reefs to come back to life and re-emerge?
What enlightenment did the mass extinction of life more than 300 million years ago give mankind?
A reporter from Science and Technology Daily learned from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences on December 14 that the late Paleozoic research team Yao Le associate researcher and Chinese and foreign scholars have used a large number of Chinese specimens to witness the recovery and evolution of reefs after the mass extinction of organisms in the Late Devonian. The process and results were published in the international journals "Earth Science Review", "Sangu" and "Geological Journal".
Two specimens from Gansu and Guangxi restore the rebirth of reefs
In the middle and late Devonian period between 385 million and 371 million years ago, the earth ushered in an important stage of life evolution.
During this period, the largest metazoan reef system developed in the ocean since the origin of life, with layer foraminifera and coral as the main reef-building animals.
But 371 million years ago and 359 million years ago, there were two biological extinction events, and the layer foraminifera-coral reef ecosystem collapsed and disappeared.
From today's perspective, the corals and layer foramen that make up Devonian reefs are relatively lower animals, but reefs contain the most complex and diverse ecosystems in the ocean and are also the most important gene treasure house in the evolution of life on earth.
"In order to reveal whether the recovery and evolution process of China's Mississipian reef after the extinction of the Late Devonian organisms is consistent with that of the world, we have studied in detail the stromatolite reefs of the Qianheishan Formation at Dashuigou Section in Pingchuan, Gansu. And the metazoan-microbial reef of Duan Formation at Tianlin Gandongzi Section in Guangxi." Yaole told reporters.
In the stromatolites of the Heishan Formation before the Dashuigou section in Pingchuan, Gansu, they found a large number of micrites, micrites, nucleolites and sprite calcites. "These substances are very small calcium carbonate particles, such as micrites with a diameter of no more than 4 microns, they indicate that stromatolites may be formed by the bonding, trapping and calcification of microorganisms." Yaole said, this is the microbial reef that replaced the metazoan reef after the Devonian extinction.
On the Tianlin Gandongzi section in Guangxi, abundant reef specimens were also found, ranging from a few meters in size to tens of meters in size.
Studies have shown that the "builders" of these reefs are mainly clump corals, horizontal plate corals, cell bryozoans, and microorganisms. However, metazoans such as corals have taken the lead and the microbial reefs are declining.
"We can determine that the stromatolites located in Gansu are in the early Dunet through fossils such as ammonites, ostracods, and sporopollen, and the Guangxi reefs are determined to be the late Weixian through the foraminifera fossils. The difference between the two is about 23 million years." Let's talk about it.
Metazoan reefs and microbial reefs are like seesaws, where the prosperity of one side means the decline of the other.
The mass extinction of organisms in the late Devonian led to the collapse of metazoan reefs such as corals and layer foraminifera. The microorganisms that had been squeezed into the corner took the opportunity to occupy the shallow sea territories, developed their own teams, and formed a large number of microbial reefs.
After 23 million years, the earth’s climate warmed and metazoans prospered again. Those microbes became the “meal on the plate” of coral polyps, and the situation reversed and became beneficial to the metazoans.
The mass extinction of coral reefs heralds major problems in the global climate and environment
Reefs are not only the most important gene treasure house for the evolution of life on earth, but also the "warning light" of changes in the earth's climate and environment.
Some people might say, if I don’t go diving in the Great Barrier Reef, what does the destruction of coral have to do with me?
"Through the study of geology and paleontology, we know that coral reefs are a fragile ecosystem, which is very sensitive to changes in the climate and environment." Yaole told reporters that once coral reefs die out in large numbers, it means that the ocean and even the earth's climate environment will have major problems.
More than 300 million years ago, the main reason for the prosperity of coral reefs was the warming of the earth. The temperature at that time was even higher than today, and there was no ice sheet in the Antarctic region.
So, does it mean that we don’t need to worry about global warming?
the answer is negative.
According to Yaole, after hundreds of millions of years of evolution, today's corals are not the same as their ancestors. They have many algae in their bodies, and the two sides are mutually beneficial and symbiotic.
Once global warming, it will cause a large number of deaths of algae. After this pair of good friends who share weal and woe are dismantled, coral reefs will also face collapse.
At the same time, global warming will cause ocean water to acidify, which will be a fatal blow to sensitive coral polyps.
"Our research found that the restoration of biological reefs did not happen overnight. It took 23 million years. The biological reefs are an important ecosystem in the ocean." Let's say that biological reefs protrude from the seabed and are very hard. Resist the impact of waves and provide habitats for all kinds of marine life, "It is like a high-rise building built on the ground. Once an earthquake occurs, the buildings will collapse. Where do we humans live?"
Our reporter Zhang Ye