Eight thousand eggs cyprinid fish, which environmentalists have fed eight mallards with excrement came the twelve embryos of the three of them hatched fry. The authors of an article published in the journal Proceedings of the National Academy of Sciences, believe that the carp fishes can settle with zoochore.
It is known that fish are able to move great distances, including in lakes and ponds that are not connected to the original habitat of the population. Theoretically, the eggs of fish can fly from one pond to another on the feathers and legs of waterfowl, but evidence for this mechanism is almost not there.
Another possible way of moving of the eggs — endozoochory, that is spread through the digestive system of animals that eat eggs and in a few hours, remove them with feces. Through the intestines of birds settled, some invertebrates, plants and even fish Killy. The zygote may enter diapause (a state in which all physiological processes are inhibited) and covered with a dense shell, it is not surprising that embryos can survive in the hostile environment of the digestive tract. Can the caviar of other fish, covered with soft shell, spread with endozoochory unknown.
Scientists from Hungary, Spain and Romania under the leadership of Arsoli Vince (Vincze Orsolya) from the University of Babes-Bolyai fed eight mallards (Anas platyrhynchos) three grams (about 500 pieces) artificially fertilized eggs of carp (Cyprinus carpio) in the first experiment, and the silver crucian carp (Carassius gibelio) in the second. Through different periods of time, the researchers collected excreta of ducks and were filtered from whole eggs, which are then incubated. Representatives of the carp was chosen because of their high invasiveness, and because the structure of their eggs is typical for bony fish.
All of the excrement was able to retrieve eight eggs of carp and ten carp (six of them proved to be unsustainable); only two of the eight ducks in the feces did not find any eggs. Most of the embryos have passed the digestive tract of mallards per hour (during this time, the ducks can fly up to 60 kilometers), and only one in four to six hours. Of the 12 eggs nine died from fungal infections, and the remaining three hatched fry.
Scientists say that birds often eat the eggs of other fish because it has a lot of fats and proteins. One fish can lay thousands of eggs at a time, and to create colonies sometimes only a single species (silver carp, for example, can reproduce asexually by the way). So, despite the fact that in the experiment in the digestive tract of the ducks survived a mere 0.2 per cent of the eggs, the likelihood is high that the carp are settled with the help of sokorai.
Often plants and animals settle where they were not expecting, and disrupt local ecosystems. In the test, “Immigrants or invaders?” we talked about six invasive species and the ways in which people try to control them.