As more humans inhabit coastal regions, a global “anxiety” is developing about the health of our aquatic ecosystems. This anxiety is particularly prevalent in the United States, where more than half the population now inhabits coastal freshwater or marine ecosystems. One component of the National Oceanic and Atmospheric Administration’s (NOAA’s) Oceans and Human Health Initiative addresses the concept of marine sentinel organisms. As discussed by Grosell and Walsh (this issue), such sentinels are used to gain early warnings about current or potential negative trends and impacts. In turn, such indicators and warnings will permit us to better characterize and potentially manage negative impacts on human and animal health associated with our oceans.