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Stress and Immune Effects of Climate Change on Painted Turtles

Paper Reviewed
Refsnider, J.M., Palacios, M.G., Reding, D.M. and Bronikowski, A.M. 2015. Effects of a novel climate on stress response and immune function in painted turtles (Chrysemys picta). Journal of Experimental Zoology 323A: 160-168.

Noting the common assumption that climate change may subject animals to increasingly stressful environmental conditions that could have negative physiological consequences if the stress levels are elevated for long periods of time, Refsnider et al. (2015) collected painted turtles from four populations that were spread across the species' current geographic range, after which they conducted a common-garden experiment with them in one of the population's local climate zone. Specifically, they measured levels of the stress hormone corticosterone and tested two different aspects of innate immune function -- bactericidal capacity and natural antibody agglutination -- at both the time of capture and at three additional times spread over the course of one year.

This work revealed, as they describe it, that (1) "the four populations did not differ in corticosterone levels over the course of one year," that (2) "corticosterone levels were also similar at each sampling period except that post-hibernation corticosterone levels were significantly lower than the previous three time points," that they (3) "found no evidence that elevated corticosterone depressed immune function in the painted turtle," thereby indicating that (4,5) "turtles exposed to novel climatic conditions did not display a detectable stress response, nor did the novel climate depress immune function in the transplanted populations."

In light of these findings, therefore, the four researchers concluded that "in terms of innate immune function, freshwater turtles may be resilient to at least modest changes in climatic conditions."

Posted 10 July 2015