Abstract
The possibility of detecting aquatic pollution problems to take corrective decisions is intimately related to the organization levels of the living matter. Measurements at the biochemical or physiological levels detect more quickly and specifically the presence of several toxic compounds, allowing its utilization in a prospective way, until that deleterious effect reaches higher organization levels. The detection of environmental “hot spots” needs general nonspecific biomarkers if no previous information about the presence of specific pollutants exist. Since several xenobiotics can modify directly or indirectly the balance between pro-oxidant and antioxidant concentration, the determination of oxidative stress (DNA damage, protein oxidation, lipid peroxidation) in aquatic species is commonly used as a nonspecific biomarker. On the other hand, acetylcholinesterase activity or determination of metallothionein concentration (or expression) represents specific biomarkers that indicate the presence of anticholinesterasic compounds (organophosphorus pesticides or neurotoxins, for instance) and metals, respectively. The fact that animal populations inhabiting polluted areas can express responses qualitatively and quantitatively different from those of reference areas has lead to the “pollution induced community tolerance” approach that seems to be a valuable tool to compare toxicological responses of different aquatic populations.