Developmental Abnormalities in Tadpoles as Biomarkers to Assess the Ecotoxicity of Traditional and Emerging Pollutants

Aquatic environments are constantly affected by residues that end up disposed through effluents or water drainage. Most amphibian species present embryonic and pre-metamorphic phases into the aquatic environment, which makes them possible victims of such compounds. After hatching, the amphibian skin is highly permeable, which facilitates chemical absorption. Thus, these vertebrates are extremely relevant for ecotoxicological studies as they represent sensitive bioindicator species to evaluate the toxicity of many compounds. Many pollutants have been described as possible triggersof malformations in the early stages of amphibians and distinct developmental biomarkers can be used to evaluate the ecotoxicity of these substances. The presence of developmental abnormalities in amphibians has gained scientific attention for years, with an alarming increase in the causes of extra limbs, missing parts, or the altered morphology of body parts and internal organs. In this chapter we have summarized some of the main studies that reported malformations in amphibian larvae in response to emerging contaminants, including agrochemicals, micro and nanoplastics, nanomaterials, road salts and pharmaceuticals. Although many knowledge gaps still need to be filled in amphibian ecotoxicology, these studies reinforce the importance of recognizing sensitive and early biomarkers so that environmental studies can be more efficient.