The Role of Microalgae as Bioindicators of Aquatic Contamination

Physical and chemical parameters, if used in an isolated way, may not reflect the actual state of water quality, nor the effect of contaminants on aquatic biota. Thus, biological tools have been developed and applied to assess the water quality and the effects of the contaminants on various aspects of the biology of living beings exposed to these substances. The presence, quantity, and distribution of some species, called bio indicators, can help to determine the water conditions, as well as the environmental impacts provoked by pollutants dumped in water bodies. One of the most used indicators of water quality is microalgae. These single-celled organisms can be found in freshwater or saline aquatic environments, playing fundamental importance as primary producers in the trophic chain. These organisms respond quickly to physical and chemical changes in the water, as well as to the presence of pollutants and enrichment of organic matter, which makes them widely used as bio indicators of aquatic contamination in several studies. Currently, there are internationally standardized eco toxicological tests that use microalgae as bio indicators, which, associated with the assessment of the presence of a contaminant, help to establish water quality criteria and policies to protect the environment. In this context, this chapter aims to present how microalgae species are used as bio indicators of water quality in the most diverse aquatic ecosystems and discuss their potential as an early sentinel in contaminated water bodies.