The Utility of Combining Stable Isotope and Hormone Analyses in Marine Megafauna Research

Biologist, Dr. Camryn Allen, examines sea turtle blood samples separated via centrifugation. The samples were collected from green turtles during night captures to use molecular techniques that can detect early warning signs or provide more in-depth details to better understand and protect endangered marine wildlife (Photo: Ralph Pace, please contact photographer for all use).

Stable isotope and hormone analyses offer insight into the health, stress, nutrition, movements, and reproduction of individuals and populations. Such information can provide early warning signs or more in-depth details on the ecological and conservation status of marine megafauna. Stable isotope and hormone analyses have seen rapid development over the last two decades, and we briefly review established protocols and particular questions emphasized in the literature for each type of analysis in isolation. Little has been published utilizing both methods concurrently for marine megafauna yet there has been considerable effort on this front in seabird and terrestrial predator research fields. Using these other taxa as examples, we offer a few of the major research areas and questions we foresee as productive for the intersection of these two methods and discuss how they can inform marine megafauna conservation and management efforts. Three major research areas have utilized a combination of these two methods: (1) nutrition and health, (2) reproduction, and (3) life history. We identify a fourth area of research, examinations of evolutionary versus ecological drivers of behavior that could also be well served by a combined stable isotope, and hormone analyses approach. Each of these broad areas of research will require methodological developments. In particular, research is needed to enable the successful temporal alignment of these two analytical techniques.

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Fleming AH, Kellar NM, Allen CD, Kurle CM. The utility of combining stable isotope and hormone analyses in marine megafauna research. (Published in Frontiers in Marine Science).