Different methods are used in environmental research. One of them may be bioindication. This approach involves studying the state of certain living organisms to obtain information about their habitat. To understand the features of conducting such studies, one should consider what a bioindicator is. This will provide the necessary information about such a research methodology.
General definition
A bioindicator is a living organism, and possibly a whole species or community that lives in a certain ecological system and can serve as a reflection of its state. Moreover, during the study, the number of individuals in the population, their condition and behavior are estimated. Based on the information received, it is possible to judge the presence of pollutants, toxins, carcinogens, etc. in the natural habitat.
Bioindicators are plants or animals whose condition directly depends ontheir environment. The use of such a technique in the course of the study has many advantages. Sometimes it is possible to obtain the necessary information about the state of the environment only on the basis of bioindicators. Saving money and time on complex physical and chemical analyzes is a definite advantage.
Bioindicators - plants and animals that summarize important data about pollutants, the rate of change. They allow you to determine the place of accumulation and ways of entry of harmful substances, the degree and severity of the effect of toxins on living beings, including humans.
In the course of research, the biocenosis of such indicators is assessed. At the same time, both representatives of fauna and flora are interesting for researchers. In the course of observations, it is possible to assess the degree of chronic exposure to toxins even at low concentrations. They affect the functions and general condition of the internal organs of animals, symmetrical parts of the body and their ratios.
Typology
Bioindicators - plants and animals that live in water, air, soil. Such organisms can be bacteria or algae, as well as invertebrates, such as crustaceans, ciliates, molluscs. Data on fish, animals can be used during the study.
Bioindicators of soil are most often plants growing in the wild. According to their condition, it is possible to determine the acidity, moisture capacity, density and temperature of the soil. Also, by the appearance of certain plants, one can determine the oxygen content in the soil, the amountnutrients, as well as s alts and heavy metals.
Coniferous trees can provide soil information throughout the year. In this case, not only morphological indicators are used, but also a number of biochemical changes. This allows you to get reliable information. Morphological characters are sometimes variable.
So, for example, ordinary nettles can demonstrate how much calcium is in the soil. Some plants are gallophiles. They love saline soils. If they grow in a given area, actively colonizing territories, then the land is gradually s alted.
To assess the state of the water, studies are carried out on such bioindicators as the larvae of some insects, certain types of algae, higher crustaceans, luminous bacteria.
Mosses and lichens can be air bioindicators. Their physical qualities vary greatly depending on growing conditions.
Features of choice
Plants and animal bioindicators are selected for research according to a certain principle. It was formulated by one of the most famous American ecologists Yu. Odum. He proposes to take into account the following statements during the selection of bioindicators:
- There are stenotopic and eurytopic species of living organisms. The former are able to live only under certain conditions, so their scope is limited. Eurytopic species are widely distributed in nature, have ecological endurance. Therefore, they are less suitable for research than stenotopic species.
- Larger types of bioindicators are studied more often than small ones. This is explained by the turnover rate in the biocenosis. It is higher in small species, so at the time of the study they may not get into the sample, especially in the process of analysis with a long frequency.
- To select a species or their group for research, experimental and field information about the limiting values of a certain factor will be required. At the same time, possible compensatory reactions of the bioindicator, species tolerance are taken into account.
- The proportion of different populations, species or communities is more indicative and is therefore used as a reliable indicator. Only one species cannot fully convey the scale of environmental changes. Such changes need to be considered as a whole, and not just in one direction.
It is also worth noting that the best bioindicators are species that provide an immediate response, as well as the reliability of the information provided. The error should not exceed 20%. Also, with the help of such bioindicators, it should be easy to obtain the necessary information. The species must be constantly present in nature so that the researcher can assess its condition at any time.
Varieties
There are different kinds and types of bioindicators. All living organisms suitable for such research can be divided into two groups:
- Registering.
- Accumulative.
In the first case, living organisms react to changes in the environment by changingpopulation size. They can also change the phenotype, somatic disorders or tissue damage. Various deformities may appear, the growth rate changes. Other highly visible signs may also be present.
For example, registering bioindicators are lichens, tree needles. Necrosis, chlorosis, dryness appear on them. Recording bioindicators do not always allow to establish the causes of the changes that have occurred. In this case, additional research will be required to determine why the population, final appearance, distribution in nature, etc. have changed. Such changes can be the result of various processes.
Organisms-bioindicators can be of accumulative type. They concentrate toxins, pollution inside their body, in different tissues, body parts or organs. During the study, the degree of environmental pollution is determined after chemical analysis. For example, shells of crustaceans, insect larvae, as well as some organs of mammals (brain, kidneys, spleen, liver, etc.), mosses can be an accumulating bioindicator.
Living organisms react immediately to the whole complex of harmful substances entering the environment. Therefore, such a technique does not allow to establish the exact concentration of an individual toxin. But at the same time, the advantage of using bioindication allows you to determine exactly how, how much pollution affects the population.
Test organisms
The test organism can be a bioindicator of the environment. These are representatives of flora or fauna that are used in the course of quality control of the environmental conditions in the laboratory. They carry out appropriate experiments. It can be, for example, unicellular, protozoan, arthropods. Plants such as mosses or flowering plants can also be test organisms.
The main feature of such organisms is the possibility of obtaining cultures from genetically homogeneous plants or animals. In this case, the prototype is compared with the control. This allows you to get reliable information about the disturbing factor. Otherwise, due to normal individual differences between individuals, it will not be possible to obtain a reliable result.
Analysis methods
Bio-indicators and contamination of their environment are examined by comparative analysis with a control specimen. There may be different approaches to this.
The first method involves comparing the corresponding characteristics outside the area of influence. So, for example, plants grown in the zone of industrial pollution are compared with crops that grew outside the area of anthropogenic influence.
The second technique involves comparing the sample with the results of the experiment. One part of the test plants is in contact with polluted air, soil, water in laboratory conditions, and the second part is in contact with clean media.
When using the third method, historical standards are used for comparison. This would be useful, for example, whenexploration of the European steppe. Today, this ecosystem has practically lost its original appearance. It is with how the steppe looked in the past that it is compared in the present.
The fourth technique uses control. This is a certain type of dependence, the deviation from which is regarded as a violation. For example, for undisturbed species communities, a corresponding graph is constructed. If any deviations are observed, this will be immediately noticeable when comparing the two curves.
Bioindication methods
Bioindicators in nature are studied with the help of appropriate environmental monitoring. It is carried out both at the micro and macro levels. Bioindicative studies can be biocenotic and species. In the second case, the presence of an organism in the environment and the frequency of its occurrence are studied. Physiological, biochemical, anatomical and morphological properties of the bioindicator can also be studied.
In the course of a biocenotic study, species diversity is taken into account using a system of appropriate indicators, as well as community productivity.
According to the impact of various factors on the system, bioindication monitoring can be specific and non-specific. They study the reactions of a species to the appearance of pollution, toxins in their habitat. With nonspecific bioindication, the same reaction can be caused by different factors. If the changes that occur are due to the influence of only one factor, we are talking about a specific indication.
So, for example, conifers and lichenscan provide information about the purity of the air in the region, the presence of industrial pollution in their habitats. The list of plant and animal species that live in soils is specific for different types of soil. If changes occur in these groupings, we can talk about soil contamination with chemicals or a change in its structure due to human activities.
Today it is believed that instrumental studies are most effectively used in combination with bioindicators. Such a symbiosis provides the most complete, reliable information about the state of the population, the impact of adverse factors on it.
Soil bioindication
Using bioindicators in the study of soil pollution, it is possible to obtain reliable results. Plants provide information about soil fertility. A complete analysis of the composition of the soil requires a lot of time and effort. The soil is considered fertile if nettles, raspberries, celandine, valerian, etc. grow on it. These plants do not survive on poor soil.
Angelica, lungwort, meadow fescue, etc. give out moderately fertile soil. Peat mosses, lichens, cranberries, lingonberries grow on low-fertile soil.
In addition to the indicator of fertility, the composition of the soil can also be determined from plants. The presence of a large amount of nitrogen is evidenced by such plants as wheatgrass, raspberries, goose cinquefoil, knotweed, etc. The color of such plants will be bright green. If it is pale, then there is little nitrogen in the soil. Plants have reduced branching and the number of leaves.
A number of othersminerals, acidity and other features of the soil can be determined in the soil using bioindicators.
Air bioindication
A bioindicator is a living organism that significantly changes its qualities when deviations occur in the environment. With their help, you can determine whether the air is polluted. Phytocenosis is greatly affected by pollutants such as nitrogen oxide, sulfur dioxide, hydrocarbons, etc.
Plant resistance to such toxins is different. Even a small amount of sulfur dioxide in the air is easy to determine with the help of lichens. Among plants, the increased content of this type of pollutant can be determined by coniferous trees.
Wheat, fir, corn, spruce, garden strawberries, etc. are sensitive to the content of hydrogen fluoride in the air, hydrogen chloride, etc.
Water bioindication
For water quality control, bioindication is one of the best methods. Unlike chemical and physical methods of monitoring, this approach is the most objective. Special equipment is able to track only certain types of pollution. Bioindication reveals complete information about the state of the surrounding aquatic environment.
Monitoring allows you to assess for which areas of operation a reservoir is suitable. One of the simplest ways to bioindicate water is to use yeast cultures. A nephelometric assessment of the turbidity of the liquid is carried out. It depends on the amount of yeast in the sample. If water inhibits their development, the sample will be lighter than the control sample.
Pisces can alsobe used as a bioindicator. They accumulate toxins in their body. As a result, it is possible to establish what qualities characterize the water in a river or lake by visually evaluating the condition of the fish.
