Hormones At Sea: New Frontiers in Marine Mammal Endocrinology and Ecophysiology

Synopsis

Marine mammals face a myriad of environmental and anthropogenic impacts in today’s oceans, including shifts in sea surface temperature, prey availability, and ice cover; upwelling failure; vessel traffic; entanglement; noise; diseases; ecotoxicants and more. Individual marine mammals respond to such challenges with physiological changes that both reflect and affect individual health, body condition, reproduction, and ultimately, population trends. Endocrine tools can offer powerful insights into the causes and consequences of these physiological shifts, but their application remains limited due to the logistical difficulties of locating and sampling large-bodied, free-swimming and often migratory marine mammals. This special issue of Integrative and Comparative Biology highlights recent innovations in marine mammal endocrinological research that have expanded the research toolkit available, the taxa that can be studied, and the questions that can be answered. In this introductory article, we summarize the history and current state of the field and briefly review recent advances in sample types, methodologies, and statistical tools. Together, the studies described in this issue illustrate how endocrine tools can increasingly reveal important linkages between specific environmental events, individual responses, and population impacts, even in previously enigmatic and cryptic species of marine mammals. As the impacts of global climatic shifts and anthropogenic activities in the marine realm continue to intensify, continued innovation in methodologies, cross-disciplinary approaches, and statistical frameworks will increasingly be necessary to predict how both individuals and populations will respond, as well as to identify possible mitigations and management approaches.