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What risks do the contaminants really represent? A standpoint on effects from organisms to ecosystems/landscapes based on non-forced aquatic exposure scenarios

Abstract:

The present essay has as main goal to discuss the risks of the contaminants when their effects are assessed under non-forced aquatic exposure scenarios. Endpoints in ecotoxicology have initially focused on mortality, but promptly evolved to more sensitive and relevant sub-lethal responses, although forced exposures to contamination have continued to be almost exclusive. Recently, a complementary approach using non-forced exposures, thus allowing organisms to actively avoid contaminants, has been fostered. This perspective provides a novel paradigm for ecotoxicological studies by shifting the focus from individuals to higher levels of biological organisation, even under mild contamination scenarios in which noxious (physiological) effects at the individual level are not reached. Additionally, the concept of habitat selection/preference due to the simultaneous presence of contaminants with other attractive or repulsive stimuli is integrated and here discussed in light of a multi-stressor approach. This essay therefore discusses the above-mentioned concepts and how non-forced exposures can increase the ecological relevance in environmental risk assessment schemes and resulting environmental decisions.