A biological indicator , also an indicator species , pointer type , pointer organism or an indicator organism , is an organism that responds to environmental influences with changes in his life functions or attaches substances or incorporating into the organism. These environmental influences are often caused by humans. The reaction to certain loads as well as location and environmental conditions, for example moisture, light, warmth, pH value , nutrient conditions in the soil and water or air pollution is used in environmental observation or environmental monitoring .
Measurable metabolic products of bioindicators are also called biomarkers . The more meaningfulness of a bio-indicator, the more sensitive it is to changes in external influences. The value of using bioindicators lies in the savings in measurements or examinations, which as a rule would have to be carried out over significantly longer periods of time.
There are sensitive or reactive bio-indicators ( reaction indicators ). These are sensitive organisms that react quickly, selectively and highly sensitively to the entry of pollutants into their habitat (e.g. goldfish in chemical plants, which are highly sensitive to groundwater pollution , a method that is no longer very common today → animal welfare ).
Besides there is the accumulative bioindicators ( accumulation indicators ). These are living beings, mostly plants, which accumulate certain pollutant inputs (e.g. elderberry as a fluorine collector) and thus make it detectable without showing any early damage themselves.
A distinction can be made between active and passive processes. In the active process, bioindicators are placed in another environment (exposed) in order to be observed there or later removed for analysis. In the passive method, bioindicators are observed in their natural environment or taken from their natural environment for analysis.
|Procedure||Indicators||commitment||Measured value||Statement objective|
|Passive procedures||Lichen mapping||R.||Species number and
|Soil moss on open spaces in the forest (moss monitoring)||A.||Accumulation of heavy metals and nitrogen||Regional background exposure for the past 2–3 years
Conifers in the
|Conifers in the
of sulfur , fluorine ,
heavy metals, etc. a.
|herbaceous plants, grasses, shrubs, woody plants||R.||Beginning of the phenological development phases of the plants||Temporal change of the beginning of the phase Climate change , phenology|
|Active procedures||Lichen exposure||R.||Necrotization||General stress
|Tobacco plants||R.||Necrotization||Effect of oxidizing
of sulfur , fluorine ,
heavy metals, etc. a.
(e.g. Italian ryegrass )
of sulfur, fluorine,
heavy metals, etc. a.
|Current exposure to
R = reaction indicators, A = accumulation indicators
Naturally occurring bio-indicators include a.
- Aquatic organisms to determine the water quality ( saprobic index )
- Plants or plant communities to determine the soil quality (content of nitrogen , pH value , water supply, ...) Subject area: Geobotany
Artificially introduced bio-indicators have also already been standardized. Examples:
- Lichen for determining air pollution
- Grass culture (air pollution)
- Soil moss (air pollution by heavy metals; moss monitoring)
- Tobacco plants (ozone pollution, air pollutants)
- Daphnia (crabs) (water quality)
- Minnows (fish) (monitoring of drinking water quality)
Bioindicators have been used in environmental control for around 4 decades, such as B. the issuer monitoring (kale, ryegrass), used. More recently, they have also been used in nature conservation and landscape planning ( success checks , status analyzes ) and in nature conservation research. Depending on the objective and the task at hand, a number of animal and / or plant species can take on indicator functions. Pointer types for the characterization of still and flowing waters are, for example, dragonflies , as they make complex demands on the habitat with regard to the structural diversity of the vegetation, the existence of different sub-habitats and their interlinking. At the same time, it is possible to use the detection of exuvia ( larval skins ) of aquatic dragonfly larvae to assess the rate of reproduction or the quality of the water.
Even birds as intensely observed since ancient class of animals are important bio-indicators whose population declines important insights in the past with regard to contamination by pesticides (eg. As DDT ,) Mercury delivered and other toxins. The observations of birds more than half a century ago (as of 2015) - and even before clear statements from meteorology - provided indications of global warming .
When assessing the quality of waters, the saprobia (certain types of fungi , bacteria and protozoa ) found in the water are also used as indicators. Different saprobials are typical for certain degrees of pollution.
Advantages and disadvantages of the biological and the chemico-physical methods
- indicate the totality of all individual components with tolerance values
- allow comprehensive, exact statements
- are not dependent on calculation models for comprehensive statements
- indicate the long-term value of individual components with a random sample
- indicate compliance with, falling below or exceeding tolerance values for individual components
- provide information about individual effects and the interaction of various components
- simple, low cost
- work with measuring devices that cannot fail
- sensitive, as they can accumulate even the smallest pollutant concentrations over a long period of time and thus make them detectable
- can detect previously unknown toxins
- The quantification shows poor precision.
- Chemical-analytical methods provide precise values for selected individual components.
- These methods indicate the current value of individual components with a random sample (low inertia).
- Long-term measurements allow the determination of exact fluctuations in the measured individual components.
- These methods only allow precise statements to be made selectively.
- Comprehensive statements can only be made using computer models.
- Information is selective and can only provide information indirectly about individual effects or the interaction of different components.
- Analytical systems are complicated and incur ongoing maintenance and reagents costs.
- In the event of an unexpected failure of measuring devices, there are time periods without measured values.
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