Endocrine disruption of pharmaceuticals on marine organisms: Thyroidal, gonadotrophic, and behavioral responses

The effects of pharmaceutical-related endocrine disruptors (phEDCs) in marine habitats encompass toxic effects, metabolic disturbances, and growth impairments, mainly in freshwater environments and in a few key model species. phEDCs include a set of components (non-steroidal anti-inflammatory drugs, antibiotics, cytostatic drugs, anti-epileptics, antidepressants, anti-neoplasics, β-blockers, blood lipid-lowering agents, and steroidal hormones, among others) designed to target specific signaling pathways. In doing so, phEDCs are able to damage hierarchical cascades of mutual influencing endocrine circuitry in vertebrates, namely, the gonadal, thyroid, and stress-related axis, which, in turn, affect immune and behavioral responses to endocrine breakdown. In marine invertebrates, several orthologues of vertebrate endocrine mediators remain evolutionary conserved, but the adaptive mechanisms of cross-talk between high-order physiological regulatory systems have been extensively analyzed in fish and specifically in teleosts. In this chapter, we review the effects of phEDCs in marine organisms, with a focus on fish, based on thyroidal, gonadal, and behavioral aspects.