Why can fish appear in completely isolated waters?

Scientists have always had a headache searching for answers about why in some lakes and ponds isolated in arid areas, there are still . fish living. Obviously the fish don't have legs to move on their own.

A new study has shown that most of the acne actually does not cross the side of a duck's digestive tract, but in reality there are rare cases with such a small percentage of 0. , 2% of acne . still alive to continue hatching. This may be the cause of the emergence of fish in unthinkable places.

This type of journey, scientists call endozoochory (dispersed through the intestines of animals) , is a common transport tactic for plant seeds, which is also known in some insects. But the first evidence that fish also has this ability was found only recently, when the eggs of a fish called Killi survived to hatch after being eaten by a swan.

Caviar is moved to such remote places also by catching on the feet of birds, beaks and feathers .

Not only that, the eggs of the Killi fish are abnormally hard, which can remain in dry soil for months as a hibernation pattern, until the rain returns.

Scientists believe that acne is being moved to such remote areas by sticking to bird's feet, beaks and feathers but there is no real evidence for this.

To test this idea, biologist Ádám Lovas-Kiss from the Danube Research Institute in Hungary and colleagues fed the blue-necked duck (Anas platyrhynchos) to the eggs of two common fishes, the common carp and the crucian carp. .

One of eight birds is fed about 500 eggs. Of these, 18 eggs were recovered from duck manure. Twelve still have a chance of survival but only 3 bloom successfully.

Although the survival rate may seem awful, when you consider all the available caviar and all waterbirds are known to enjoy the feast on nutritious caviar, that's another story.

A common carp can lay up to 1.5 million eggs in a single spawning and at certain times of the year, caviar can account for up to 100% of the stomach content of some water birds. .

"Such survival is not a singular event. It happens in 75% of experimental ducks and in both studied fish species ," the researchers said.

Most carp eggs take only an hour to move from the input and output of a duck. The team calculated that this is the equivalent of a range of about 60km for the eggs to spread. One of the eggs will hatch after 4-6 hours, increasing that range to a maximum of 360km.

This explains a lot of things. For example, carp is a notorious invasive species. Common carp dominates Australia's waterways, accounting for more than 80% of the fish biomass in some areas. They cause damage to fragile ecosystems by modifying waterways through their mud eating habits, they get valuable food from native species and contribute to algal blooms.

The ability of carp to disperse through endozoochory, along with their adaptability across a wide range of environments, helps explain their incredible success in invading new lands and is a key information for people. Try to manage their invasion.

"With the abundance, diet and movement of ducks in the wild, our results have great implications for biodiversity conservation and invasion in freshwater ecosystems , " Ádám Lovas-Kiss emphasized.