Stress Hormones Equal Survival for Marine Iguanas

Marine iguanas living in the Galapagos Islands are considered to be vulnerable species, and are currently the object of various protection and conservation programs. Researchers say that, other than human poaching, the creatures are also subjected to tremendous influences from the El Nino weather phenomenon, which has repercussions on atmospheric patterns around the world. The event can kill off some of the iguanas through indirect means, while others may survive. The difference between those who die and those who live was found to be higher levels of the stress hormone corticosterone.

The compound is very similar in composition and function to the human stress hormone cortisol, and it has been associated with the “fight or flight” response in the iguanas. According to a series of scientific researches, it would appear that elevated levels of the stuff allow marine iguanas to endure for longer under the pressure of El Nino, although the mechanisms that favor that have yet to be understood completely. Some experts suspect that the correlation may have something to do with the fact that corticosterone tends to regulate the way in which the creatures expend their energies during the crucial times when they are exposed to the weather phenomenon's effects, PhysOrg reports.

Investigators say that the chemical acts like a spigot for the body's energy reserves during stressful times, and add that elevated concentrations can easily kill iguanas, if the spigot is not closed down in time. Scientists hope to be able to use the new data to predict how the current Gulf of Mexico oil spill will affect marine and wildlife in the region. Crude has been erupting from the sea floor for more than a month now, and efforts to contain the devastation are failing. Details of the new investigation appear in the May 26 issue of the esteemed scientific journal Proceedings of the Royal Society.

“The results from the iguanas indicate that the better an individual is at coping with stress – by turning off the response as soon as possible – the better the chance they have to survive. [Ultimately, we want] to understand what causes stress in wild animals; what physiological mechanisms are turned on in response to stress and how those mechanisms help the animals survive in their natural habitats,” explains L. Michael Romero, who is a professor of biology at the Tufts University, and also the leader of the Galapagos Islands Investigation.

“As animals encounter the spill, they will have a robust release of corticosterone to help them cope with the consequences of the oil. However, those animals that can best turn off their corticosterone response once the initial danger from the oil has passed will probably be the most likely to survive,” Romero says of the animals that will be affected by the Gulf of Mexico oil spill.