The identity card

Apart from the term itself, that may seem difficult to explain in simple words, a bioindicator is no more than a living “organism” (or a set of organisms) characterized by particular traits that are very useful for the work of researchers. In practice, a bioindicator is an animal, vegetable or microbial system whose morphological variations or changes in behaviour can be used to formulate conclusions regarding the environmental conditions they are to be found in.
So, the first fundamental characteristic of a bioindicator, is that it must be able to respond to the chemical changes in the environment through alterations in its spontaneous condition. The second fundamental characteristic is that these alterations, in order to really provide information, must be easy to measure by the researchers, possibly at costs that are not too high.
It is evident that  bioindicators may also include organisms that vary greatly in their biological organization and ecological function.  Autotrophic species and also the heterotrophic species can be good bioindicators, or the taxa of a taxonomic range that is superior to that of the species (for example a family), and in some cases even the entire biocenosis of an ecosystem. Due to this enormous potential variability of the bioindicators, it may be added that the biological responses that may be useful for the studies on bioindication, are equally variable.
This consideration however needs an important specification: if it is true that almost any organism may “indicate” a process (that is taking place, or which has taken place) of deterioration of the environment, it is also true that in actual fact some organisms carry out this function much better than others, for two fundamental reasons:

  • because by their nature they “express” the chemical variations in the environment more faithfully and rapidly;
  • because their biological parameters are easier (and cheaper) to determine than those of others.

In general, therefore, the inalienable requisite that defines a good environmental  bioindicator is as follows: it must be widely distributed and easy to identify,  to sample and analyze.

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