According to its structure and principle of the natural ecosystems are open systems.An essential condition for their functioning is the ability to give and receive various types of energy and resources.Without this eternal cycle of the Earth's limited resources will sooner or later be exhausted.Furthermore, only the ecosystem is considered a system which is able to exist without external intervention.Everything needed for the operation it produces itself.In order to maintain a continuous flow of materials in any given ecosystem must be present functionally different groups of living organisms.
The size of the occupied territory, as well as the number of elements involved in the cycle of living and inanimate nature distinguishes four types of systems.At the bottom is microecosystem the simplest example of which can serve as a drop of human blood or water from the river.Followed mezoekosistemy.This category includes the ecosystem of the lake, pond, prairie, steppe, or, for example, forests.In third place are makroekosistemy that are whole continents and oceans.And the biggest ecosystem is considered to be the planet Earth itself, to be more precise - all life on it.This system is called global.
ecosystem structure
main source of energy in the lake is sunlight.When the rays pass through the water column, most of the energy is absorbed by plankton, and then to use it for photosynthesis.The remaining light is gradually absorbed the most water.Therefore, the illumination on the upper levels are always great, and closer to the bottom decreases.Any sufficiently large ecosystem of the lake is called the compensation level.This depth, which reaches the minimum required amount of light plants.Photosynthesis slows down such plants, to balance other parameters - respiration and consumption of food.
Location of the compensation level depends on the properties of water, its purity and transparency.It is a kind of notional dividing line.Above it plants produce excess oxygen, which is then used by other living organisms.A below the dividing line of oxygen, on the contrary, too little.The main part of it falls on the depth of the other, the upper layers of water.Thus, the lower compensation level found only those organisms which can dispense a minimum amount of oxygen.
overall distribution of inhabitants
It is obvious that the upper levels of the ecosystem of the lake inhabited much greater diversity of species than in the bottom zone.This fact is due to more favorable conditions for the life of food, heat and oxygen in shallow areas.They live in a variety of rooting light-loving plants: lilies, reeds, rushes, arrowhead.
They, in turn, serve as a haven for insects and arthropods, worms, molluscs, tadpoles.Also here find their own food, many species of fish.Most small arthropods, whose existence requires a large amount of light that live near the surface.Here grows freely floating duckweed.
At its lower levels of the lake ecosystem becomes a habitat for all sorts of decomposers that feed on dead remains of plants and animals.There is also home to many predatory fish such as pike and perch, and some invertebrates.These types of feed or descends from the upper layers of the water or dead creatures prey on each other.
pollution impact on lake ecosystems
One of the most important natural elements for such systems is phosphorus.From its amount depends on the overall productivity of the ecosystem.The natural content of the substance in the lake water is low, but human activity leads to a significant increase in the concentration.The main reason should be attributed falling into the lake production waste, draining of sewage, excessive use of fertilizers, which are then washed away by rain and underground streams.All of this brings to the ecosystem uncharacteristic her excessive amounts of phosphorus.
As a result, disrupted the structure and efficiency of established system: starts to increase rapidly the number of plankton, from which the water becomes turbid greenish tint.Lake begins to "blossom", but this is only the first step.Further, it is polluted with nutrients, water becomes less saturated with oxygen and sunlight (plankton absorbs huge amounts of what is needed to get other residents).Last activity violates the decomposers, which is why the water is filled with slowly rotting remains.At the final stage of the plants begin to produce toxins, causing massive fish kills.
Another kind of pollution, because of which substantially affected the ecosystem of the lake - the heat.At first glance it does not seem serious: thermal pollution in the water does not add any chemicals.But the normal functioning of the system depends not only on the composition of the medium, but also on temperature.It is also capable of improving the growth of plants trigger that starts slowly but surely fatal reaction.In addition, certain types of fish and invertebrates adapted to life in the narrow temperature within.Raising or lowering the temperature in this case, slow the growth of organisms or kill them.
This type of pollution is the result of human industrial activity.For example one that uses a lake water to cool the turbines and power plants.
