ABSTRACT
The term epigenetics was originally used to describe developmental processes. However, in the past couple of decades, the definition has shifted to focus on ways in which environmental factors can induce heritable phenotypic traits without altering the DNA sequence. The most widely studied epigenetic mechanisms include DNA methylation, histone modifications, and noncoding RNAs. Studies on epigenetic mechanisms have expanded from understanding the fundamental roles of these processes on physiology and development to assessing how environmental stressors can modulate epigenetic regulation of gene expression and phenotypes. Across taxa, stressor-mediated epigenetic changes have been associated with adverse outcomes at the cellular, organismal, and population levels. Fish are being used both as human and ecological health models to better understand the potential toxicological implications of contaminant exposure. This chapter will provide an overview of epigenetic mechanisms, summarize the existing fish studies that have investigated stressor-mediated epigenetic changes in fish, consider how epigenetic change can be incorporated into adverse outcome paradigms and risk assessment, and suggest research needs to link epigenetic changes causally to adverse toxicological outcomes.
