From childhood to adulthood, many people have had such questions:
A man-dug earthen pit has become a small pond because of the rain, but why will there be many small fish growing in the pond for no reason?
There is no artificial stocking, there is no life in the rainwater, the small pond is isolated, there is no connection with other water sources, so where do these fish come from?
The director of a French documentary has the same questions as we do.
So he organized people to observe a pond formed by quarrying, and filmed a documentary to record the whole process of the pond "long" fish - "Hidden Paradise".
While the fifty-minute film is merely about the formation of an inconspicuous pond, it's a story about an ecological wonder.
More than fifty years ago, it was popular in Europe to use gravel as a building material, so on the banks of the Rhine, there were thousands of quarries of all sizes, and this small pond was just one of them.
Due to the deep digging, there is a large influx of groundwater during the mining process, and combined with the rainwater, a small lake is formed here.
This lake is different from the naturally formed lake, it is not connected to any other water body, there is no artificial intervention to cultivate, it is a completely isolated and independent small world.
After the excavation equipment was withdrawn, the lake was completely left to nature. Over time, lush vegetation grew around the lake, and aquatic plants grew in the water.
The fish and other creatures we want to see will also slowly "grow" out.
The first animal to visit this small lake was the toad, which is what we call the toad.
In the spring, toads will look for secluded and illuminated places to lay their eggs, and as soon as one toad appears, many toads will follow.
This small lake is deserted and has no other biological predators, which is just right for toads to do shameful things.
In the absence of fish and water birds eating frog eggs, toads begin to multiply in large numbers.
After the frog eggs grow into toads and frogs, they return to the place of birth every year to lay their eggs, so it has become the home of generations of frogs and toads.
In the spring, not only toads and frogs come to visit, but also visitors from all over the world, such as migratory birds.
One of them is the warty-nosed swans that fly from the south, and they look for aquatic plants here to fill their hunger and will not let go of every part of the water.
These swans are the key to the growth of small fish in the pond.
Because swans fly everywhere to feed, they often carry small creatures on their paws and feathers, such as the eggs of some fish.
Because the first eggs were not preyed by other animals, under the right conditions, they would give birth to small fish – this is the mystery of this passive water "growing" small fish.
Of course, fish eggs are not only brought by swans, but there are other birds and migratory birds, and the bodies of toads and frogs may also become porters of life.
Once there is the first fish, there will be many, many fish. But animals alone are not enough.
On the banks of the Rhine, where this lake is located, it often rains in spring. During the rainy season, the river swells over the embankment, and various water bodies are connected.
Many animals that take the river as their home will go elsewhere with the flowing water, and more and more fish will settle in this small lake, and various aquatic plants and microorganisms will become more and more abundant.
Year after year, after about two decades, this small independent lake has finally become a biological world as rich as a natural lake.
Isn't it a bit like the illusion of a tropical ocean landscape?
But it's really just a shallow freshwater pond, and the magic of nature is so magical.
However, with the "transformation" of this small lake, many viewers should have the same question as Tomato Jun: there are thousands of quarries on the Rhine, why is this the only one that has become a natural paradise?
I think you should think of the answer: people.
Human intervention is fatal to such a small ecosystem.
A few inadvertent feet of human beings will destroy the plants that have grown here for many years, and even have a destructive blow to the shallow aquatic weeds in the lake.
Many of the thousands of quarries have not yet been transformed by nature, and they have become paradises for human beings, and nature certainly cannot turn them back into biological paradises.
Humans will also bring garbage, bicycles, car tires and plastics that cannot decompose for hundreds of years or more, which will not only pollute the groundwater, but also completely destroy such small lakes.
Even more frightening is the self-cleverness of people, especially those who are anglers.
They will stock the water with the fish they want to hoist. Fishing in Europe is still somewhat different from China.
In China, big fish hanging up is definitely on the table, but in Europe, they only enjoy fishing.
After fishing, take a group photo and the fish caught will be put back into the water.
This seemingly life-loving act is a disaster for the biodiversity of this small lake.
The number of carp will increase, because the carp is so large and strong that other fish will hardly survive.
In order to catch larger fish, these anglers also throw in a lot of bait containing organic matter, and the large amount of nutrients in these baits can cause algae to surge.
The excess algae multiplied amazingly, absorbing a lot of nutrients and oxygen from the water, and other organisms gradually died.
Under such circumstances, the small lake formed by the abandoned quarrying site cannot become a natural paradise.
Therefore, the formation of such a small ecosystem requires both the transformation of nature and the full luck of the documentary director - and the small lake chosen by the documentary director meets such conditions.
There are no roads around it, and it is surrounded by dense trees, which is difficult to spot if you don't look down from above.
What's more, with the passage of more than twenty years, although it is close to the city, it has been forgotten.
Without the interference of anyone, it can be so vibrant.
Don't look at it as small, every unexpected change will become a surprise that belongs only to it.
For example, the sudden break of a tree on the shore, the branches and leaves are immersed in water, which seems to be an accident, but it is actually a good thing.
Branches and leaves form a unique space in the water, and the intricate foliage provides shelter for fish.
The sea bass first discovered it, and then the six-whiskered catfish, which was accustomed to nocturnal activities, came and used it as a temporary bedroom during the day.
The seabream also joined the camp and began rummaging through the lakebed under the trees for its favorite snails and worms.
Not only did this dead tree become a habitat for schools of fish, but even snails climbed up to the branches to eat the algae attached to it.
Another moss- also gathers on the branches, preying on plankton and moving only at a very slow speed, which can only be seen with time-lapse photography.
There are also brightly colored colonies of bacteria at the bottom of the lake that survive on sunlight and sulfur-containing compounds in the water.
We often say: "Big fish eat small fish, small fish eat shrimp rice".
Bacterial colonies feed plankton such as water fleas, and plankton feed small fish, thus forming an entire food chain.
Standing at the top of the lake's food chain is a fish called pike.
It has sharp teeth and will swallow everything it can to fill its stomach. Female adult pikes are 1.5 meters long and are the overlords of the lake, with a lifespan of up to 30 years.
Pike fish are ferocious by nature, and when they are young, they will devour their own kind in order to survive, let alone other creatures.
After the warm season, winter comes.
As long as the lake surface is not frozen, the world at the bottom of the lake is still wonderful.
Because the pit left when the quarrying is deep and shallow, the shallowest place is only one meter, the sun can shine, and the temperature can reach 4 degrees Celsius in the deep place, which is suitable for most fish to spend the winter.
In this way, day after day, year after year, they lived in this small quarry.
On the surface, a puddle of water is actually a great natural world.
Human beings have always self-righteously ignored the power of nature, but time will prove that in the face of nature, our little cleverness is nothing more than a mistake for life.
There are thousands of similar abandoned quarries in Europe, many of which are already well placed to become natural paradises.
Just give them time and tranquility, and nature will arrange everything.
(Rotten Tomatoes Editorial Board: Yang Yang)