Bioindicators 1. IntroductionThe term’Bioindicators’ refers to any organism, species, communities or biologicalprocesses, which help to qualitatively monitor the status of the environment inwhich they live by means of their function as well as their population. Theoccurrence of any environmental change or problem within an ecosystem can bepredicted very easily by any changes in the population status, behavior, andphysiology of such organisms.
The identification of any species as abioindicator is reflected by any fluctuation in the abundance and population ofthe species in response to any environmental change in a particular habitat.Bioindicators are useful in providing information about the health of anecosystem since the organisms of these species are highly sensitive to the changesin their surroundings. Therefore, the sampling and studying about thepopulation dynamics of such organisms makes it possible to monitor anyecological changes. This in turn helps in identifying the positive and negativeeffects of human activities in that area. A bioindicator has certainrequirements regarding a known set of physical or chemical variables such thatvariations in the presence or absence, morphology, physiology, population orbehavior of the given species suggests that the prescribed physical or chemicalvariables are outside their preferred limits. Generally, bioindicators aredenoted as species which respond to anthropogenic effects on the environment.
Amore general and all-inclusive definition of a biological indicator states: “aspecies or a group of species that voluntarily imitates the abiotic or bioticstate of an environment, represents the effect of environmental change on ahabitation, community or ecosystem or is indicative of the diversity of asubset of taxa or the whole diversity within an area”. Bioindicators helpin the assessment of the quality of the environment and how it changes over agiven period. These can be plants, animals, algae, lichens, zooplanktons,insects, amphipods, mollusks, echinoderms, and other micro-organisms. Evenhuman nail & hair can also be used as bioindicators. Bioindicators findusage in monitoring air, soil and water quality and in the assessment of theoverall biodiversity. These can also help in determining the progress ofmitigative measures implemented for environmental conservation and thus play asignificant role in nature conservation too.
The information provided bybioindicators is adequate and reliable and might be difficult to obtain orquantify in such a quick manner using other means. The usefulness of bioindicators is most observed in given threesituations: 1) when it isimpossible to measure the indicated environmental factor- e.g. in situationswhere environmental factors in the past are reconstructed such as climaticchange, studied in palaeo-biomonitoring 2) when themeasurement of the indicated factor very difficult- e.g.
pesticidesand their remains or complex toxic effluents comprising several interactingchemicals and 3) when themeasurement of the environmental factor is possible and easy but theinterpretation is quite difficult- e.g.whether the observed changes are of ecological significance.