According to Depledge (1993), a biomarker can be defined as:
“… a biochemical, cellular, physiological or behavioural variation that can be measured in tissue or body fluid samples at the level of the whole organism (either individuals or populations) that provides evidence of exposure to and/or effects of one or more chemical pollutants (and/or radiations).“
Then, using biomakers can allow us to predict the occurrence of negative effects through the analysis of immediate responses. And that is why the use of biomarkers is very widespread in environmental bio-ecology and biomonitoring:
– they offer an integrate response of the bioindicator exposure, considering absorption and exposure ways;
– they offer an integrate response of the toxicological interactions and pharmacokinetic properties of the mixture of pollutants around the bioindicator;
– they provide an immediate response to exposure to toxic agents that can be used to predict long-term effects.
Bioindicators can be considered all the organisms (a parts of them) that can provide informations about environmental quality (or part of it) through specific reactions, for example biochemical, physiological, morphological, etc.
For that it is important that they meet some requirements:
– ecological optimum and wide distribution in the study area;
– easy identification and enough knowledge of the species (physiologically, anatomically, ecologically);
– genetic uniformity and long life cycle;
– low mobility and easy availability in all seasons.
Nuclear abnormalities and micronucleous are the final expression of genotoxic agents damage. They are formed during an incorrect mitotic anaphase, when isolated nuclear elements (chromosomal fragments or acentric chromosomes) form one or more smaller secondary cores in the new forming cell(s).