Bioindicator

Biological indicators are species that can be used to monitor the health of an environment or ecosystem. They are any biological species or group of species whose function, population, or status can reveal what degree of ecosystem or environmental integrity is present.

Such organisms can be monitored for changes (biochemical, physiological, or behavioural) that may indicate a problem within their ecosystem. Bioindicators can tell us about the cumulative совокупный effects of different pollutants in the ecosystem and about how long a problem may have been present, which physical and chemical testing cannot.

Bioindicators are commonly grouped into accumulation indicators and response indicators. Accumulation indicators store pollutants without any evident changes in their metabolisms.

Response indicators react with cell changes or visible symptoms of damage when taking up even small amounts of harmful substances.

A bioindicator is an organism or biological response that reveals the presence of the pollutants by the occurrence of typical symptoms or measurable responses, and is therefore more qualitative. These organisms (or communities of organisms) deliver information on alterations in the environment or the quantity of environmental pollutants by changing in one of the following ways: physiologically, chemically or behaviourally. The information can be obtained through the study of:

- the content of certain elements or compounds

- the morphological or cellular structure

- metabolic-biochemical processes

- behaviour

- population structure(s).

Bioaccumulative indicators are frequently regarded as biomonitors.

Bioindication is a research activity allowing us to obtain a picture of the ecological situation on the basis of its important element (e.g. species, ecological form, population, association or community). Bioindication is focused on searching for organisms that accumulate toxic substances, as their concentrations in such organisms provide the basis for estimating the level of environmental pollution with these substances.

A biological monitor, or biomonitor, can be defined as an organism that provides quantitative information on the quality of the environment around it. Therefore, a good biomonitor will indicate the presence of the pollutant and also attempt to provide additional information about the amount and intensity of the exposure.

The importance and relevance of biomonitors, rather than man-made equipment, is justified by the statement: "There is no better indicator of the status of a species or a system than a species or system itself."

The use of a biomonitor is described as biological monitoring (abbr. biomonitoring) and is the use of the properties of an organism to obtain information on certain aspects of the biosphere. Biomonitoring is based on the correlation between toxic substance concentration in the environment and living organisms

Biomonitoring is divided into passive and active.

Passive biomonitoring is the use of organisms, organism associations, and parts of organisms which are a natural component of the ecosystem (growing naturally within the area of interest) and appear there spontaneously.

Active biomonitoring includes all methods which insert organisms under controlled conditions into the site to be monitored.

Types of bioindicators and their uses include the following:

Plant Indicators -- The presence or absence of certain plant or other vegetative life in an ecosystem can provide important clues about the health of the environment. Lichens, often found on rocks and tree trunks, are organisms consisting of both fungi and algae. They respond to environmental changes in forests, including changes in forest structure, air quality, and climate. The disappearance of lichens in a forest may indicate environmental stresses, such as high levels of sulfur dioxide, sulfur-based pollutants, and nitrogen.

Animal Indicators -- An increase or decrease in an animal population may indicate damage to the ecosystem caused by pollution. For example, if pollution causes the depletion of important food sources, animal species dependent upon these food sources will also be reduced in number. In addition to monitoring the size and number of certain species, other mechanisms of animal indication include monitoring the concentration of toxins in animal tissues, or monitoring the rate at which deformities arise in animal populations.

Microbial Indicators -- Microorganisms can be used as indicators of aquatic or terrestrial ecosystem health. Found in large quantities, microorganisms are easier to sample than other organisms. Some microorganisms will produce new proteins, called stress proteins, when exposed to contaminants like cadmium and benzene. These stress proteins can be used as an early warning system to detect low levels of pollution.

An excerpt from the article “Biomonitoring of Airborne Heavy Metal Contamination” by

Mehran Hoodaji, Mitra Ataabadi and Payam Najafi

Islamic Azad University, Khorasgan Branch (Isfahan) Iran

http://cdn.intechopen.com/pdfs/33145/InTech-Biomonitoring_of_airborne_heavy_metal_contamination.pdf