Biomarkers based tools to assess environmental and chemical stressors in aquatic systems

Abstract

The quality of aquatic systems is threated by the huge amount of chemicals dispersed in the environment. Anthropogenic activities are one of the main causes of pollution by metals, water sewage, pesticides, pharmaceutical drugs and other contaminants. These substances have consequences on the environment bringing abiotic and biotic deterioration. Global Climate change (GCC) also affects the dynamics of aquatic communities affecting the toxicity of pollutants by altering their physiochemical properties and the adaptive capacity of organisms. Damages in ecosystems and thus in aquatic communities have consequences in functional and physiological roles, with impacts along the trophic food web and thus, in the food quality. The degradation and loss of the goods and services provided by theses ecosystems affect human population. To safeguard the environmental status, the European Union has implemented the Water Framework Directive (WFD; 2000/60/EC) and the Marine Strategy Framework Directive (MSFD; 2008/56/EC) legislations, which allow the use of biological tools to detect the quality of aquatic systems. The following review highlights the use of these biological tools to achieve the objective of both legislations that assures the good quality of the aquatic environment. The biological groups most used for the assessment of aquatic systems are: phytoplankton, macrophytes, benthic macroinvertebrates and fish, with several authors also consider zooplankton due to the sensitiveness of this community to stressors, although this group is not identified as a biological quality element (BQE) of WFD. Relying on bioindicators and biomarkers as supporting on chemical analyses, researchers should have a clear overview of environmental conditions. To ensure that biological tools are valid, they must deal with some criteria: they must be cheap and easy to perform; be sensitive to pollutant exposure; be reliable, with a short life span and easy to collect. Although bioindicators and biomarkers may be used as early-warning indicators of the presence of stressors, they have limitations in their applications. Thus, should be assessed and identified the most accurate and suitable biomarker to be used as endpoint in ecotoxicological studies and the assessment of the environmental status.