Bioindicators used in aquatic and terrestrial monitoring

There are many different types of contaminants present in the environment ranging from synthetic chemicals, which would not be present in the environment without man's intervention, to trace metals that are required for life. Concerns range from possible harmful effects on flora and fauna to possible harm to humans consuming such organisms. The complete chemical analysis for all possible environmental contaminants in sediments, water, air, and every species and sample of interest would not only be excessively costly, but the facilities to handle do many samples do not exist. Such chemical analysis would only establish the presence of contaminants, without revealing how available or active they were within the organism.

Bioindicators, sometimes called biomarkers, are responses in living organisms that may simply signify exposure to contaminants, may predict future harm, or may themselves be harmful effects. In this chapter, a bioindicator will be interpreted to mean the same as a biomarker (a biochemical, physiological, or morphological response), but not a population or ecosystem bioindicator such as a sentinel species, genetic variability, or species richness. thus, a bioindicator (biomarker) may be studied in a particular species to assess the status of that species, or in a sentinel species to assess habitat status. Individuals of the sentinel species might be those already residing at the site of interest or might be pristine organisms brought to the site and maintained in cages (fish) or released and recovered (birds).