The objective of this study is to characterize the epigenetic effects of exposure to hypoxia in a marine fish species (Fundulus heteroclites). Hypoxia (reduced oxygen levels) is one of the major environmental stressors in coastal marine environments, which is expanding globally. Coastal ecosystems serve as an important habitat for embryonic and larval stages of a variety of vertebrate and invertebrate species. Most of the studies aimed to understand how coastal organisms cope with hypoxia and other environmental stressors during critical periods of early development can have long-term consequences, seen only at later stages of life. These long-term effects of exposure are mediated by epigenetic regulation of gene expression. We will employ the latest technologies to quantify genome-wide epigenetic changes. Furthermore, we will determine the relationship between epigenetic changes and gene expression patterns. The results from this study will determine the mechanistic basis for the long-term effects of exposure to hypoxia during sensitive stages of early development.