Baikal is a wonderful lake of exceptional purity. What or to whom does the lake owe its peculiarity? They say that after two or three days of drowning in Lake Baikal, it is useless to search. It turns out that a small copepod lives in the lake, barely noticeable to the eye. He is surprisingly efficient, and his family is numerous. Thanks to it, water is filtered at a very high speed. Chistyulya does not tolerate the superfluous that is carried out by the rivers, thrown out of the ships or gets into the lake in another way.
Myth and reality
Unfortunately, it is very difficult for science to know for sure how many species of representatives of the animal and plant world were found in Baikal, so to speak, in the best of times for it. One by one, these species disappear due to toxic releases into the lake. So the epishura crustacean selflessly rushed to the toxic waste of the pulp mills. And this filling brought death to a small creature.
It is believed that this small creature filters out all the water in Lake Baikal. Yes, the crustacean of this species is one of the main orderlies of the lake, but it does not filter out all the dirt. Examining his oral apparatus under a microscope, one can see a cunningly entwined, like openwork trapping net of numerous cirrus bristles. In it, algae, bacteria, and ciliates are tangled.
But the episode cannot filter out everything that is in the Baikal water. It always contains turbidity, the particles of which the epishura discards.
Description
A small creature belongs to the species of planktonic crustaceans. The size of an adult is approximately 1.5 mm. An amazing creature called epishura crustacean is one of the most famous endemics in Baikal. It plays a very important role in its ecosystem and inhabits the entire water column, forming up to 90% of biomass. A small creature consumes most of the algae. For Baikal omul, the crustacean epishura is the main delicacy.
At all times of the year, different ages of this species of aquatic inhabitants can be found in the water plankton of the lake. The crustacean continuously multiplies. Fertility of females reaches 200 eggs per year. This is an average. Two generations grow in one year. The epishura crustacean propagates with the help of eggs, which the female lays and carries in an egg sac. Eggs can be from 7 to 60 pieces. They all have the same maturity.
Breeding
Females lay eggs in portions. In such conditions, each generation is represented by crustaceans from several litters. Between the clutches in the winter-spring period, a period of approximately 10 days passes, and in the summer it is about 20 days.
If the bag is damaged, as it is very fragile, eggs drop out. However, with any irritation from the outside, the female tears the sac, even if the eggs have not reached maturity. Having fallen, they continue to develop in the water.
In Baikal, you can often find single eggs in which embryos develop. As an adult, the crustacean of the Baikal epishura ceases to grow. Until maturity is reached, it goes through two stages of development: larval and copepod. Each of them has its own periods, the last of which is mature individuals. The transition between each development period is accompanied by molting.
Cleansing
For many species of flora and fauna, Lake Baikal has become a habitat. The epishura crayfish is its endemic, the keeper of purity, and therefore can claim a special place among the entire living creatures of the lake. It is almost completely immune to pressure drops. Due to this feature, the crustacean lives at different depths.
Up to 85% of permanent plankton in open areas of the Small Sea is epishura. A group of animals in Baikal, called endemic, makes up a significant part of all the inhabitants of the lake. And there are about 2600 species. Scientists suggest that not all representatives of the water world are open, but only about 70-80% of their total number.
Habitat
Epishura spends most of the time of the year in the upper layer of water. It is 250 meters. At the same time, a significant number of this species is deeper. Of course, not only the crustacean epishura performs the function of a lake cleaner. Over 800 species of underwater inhabitants of Lake Baikal are working on this problem, and not only them. However, the contribution of the above representative of the animal world is difficult to overestimate.
Characteristic
Along all the investigated depths of Lake Baikal, the epishura crustacean is found. What group of animals can boast such a population in this amazing lake? A small, almost colorless crustacean is a star of the first magnitude in its habitat. Only fat accumulations near his intestines are endowed with a reddish-orange color. Representatives of this genus are characterized by distribution both in Baikal and in Kamchatka in Lake Kronotsky and in the Far East in Lake Khanka. Six other species of the same genus found their distribution in North America.
For researchers, this invertebrate aquatic creature is interesting in itself. A study of the episode is still ongoing. Indeed, in his biology there is still a lot of mystery. The ecology of the crustacean is also not yet fully understood. Of interest are its durable silicon "teeth", as well as speciation.
How does the distribution of crustaceans in water layers change?
June and the period October-February, 30-40% of the representatives of epishura plus 40-50% of the biomass are located below the upper layer (250 meters). In spring and autumn, during the period of homothermia, the individual is distributed almost uniformly throughout the water column.
The small crustacean epishura is the most important link in the food chain of the lake. It is so numerous and dominates in any season by biomass among other Baikal zooplankton that it serves as an excellent food for all pelagic fish. In fact, there is no fish juvenile living in the coastal zone that would not eat it. Predatory representatives of zooplankton, such as large rotifers and cyclops, also enjoy this crustacean.
Where else can you find a small endemic?
In the bays of Lake Baikal, it occurs only at a time when the surface of the reservoir is covered with ice, as well as in early spring, after its melting. At the peak of heating (July, August), the animal completely disappears from the composition of plankton. Such a phenomenon is observed in Chivyrkuisky Bay. In a small amount, the crustacean is preserved in the Barguzin Bay. Epishura comes to the Ambassadorial litter in the winter. In summer and autumn, he is not there, except that he will be listed there in single copies by a strong current of waters.
In early spring, it can be found far from Proryva. With depth, the number of episures gradually decreases. The gates of large bays, under the significant influence of the open waters of Lake Baikal, are inhabited by crustaceans all year round.
Baikal waters fall into the Angara, Irkutsk and Bratsk reservoirs. You can also find episodes there. In the deep near-dam part of the Bratsk reservoir, he found a habitat suitable for reproduction. Here, the crustacean is a self-reproducing population.
Crustacean nutrition
Epishura eats algae. He uses bacteria to a lesser extent. It can be compared with a water cow grazing in phytoplankton glades. Studying the biotic cycle in the pelagic zone, scientists found that epishura seizes a third of the primary production of algae, which are the main producers of organic matter, for the whole year.
It was this feature of crustaceans in the food chain that became the reason for the widespread opinion about the key importance of epishura in the purity of Baikal waters. Its feeding method is a type of filter. And Baikal diatoms are considered their favorite food. The distance between the hairs in the oral cavity allows the use of Baikal tiny picocyanobacteria. Most likely due to this fact, the role of the main cleaner is assigned to the epicure.
