Marine mammals as sentinels for oceans and human health

As the effects of global climate change become understood, concern is being raised about the health of the Earth's aquatic ecosystems. The concept of marine sentinel organisms may provide one way of evaluating aquatic ecosystem health. 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. Marine mammals are sentinels for oceans and human health because many species have long life spans, are often long-term coastal residents, feed at a high trophic level and have unique fat stores that can serve as depots for anthropogenic toxins. Additionally, marine mammals are charismatic megafauna that typically stimulate a human behavioral response and are thus more likely to be observed. Similarly, diseases that impact these species may make humans more likely to pay attention to ocean health issues. Marine mammals can be used as sentinels for emerging and re-emerging infectious and neoplastic disease, the effects of anthropogenic toxins and the impacts of harmful algal blooms. Many of these diseases have direct public health implications while others may be indicative of an environmental distress syndrome. New opportunities for interdisciplinary and multi-institutional studies are emerging for utilizing marine mammal sentinel species and this approach will undoubtedly expand as new species are evaluated. As well, this approach provides a new avenue for better understanding the interface between intriguing ecosystem and public health issues.