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Great Bio-News for the Planet's Polar Terrestrial Invertebrates

Paper Reviewed
Everatt, M.J., Convey, P., Worland, M.R., Bale, J.S. and Hayward, S.A.L. 2014. Are the Antarctic dipteran, Eretmoptera murphyi, and Arctic collembolan, Megaphorura arctica, vulnerable to rising temperatures? Bulletin of Entomological Research 104: 494-503.

In a study published in the Bulletin of Entomological Research, Everatt et al. (2014) write that polar terrestrial invertebrates have long been viewed as being especially vulnerable to temperature change relative to lower-latitude species, such as is now predicted to occur in the very near future by numerous climate models as a result of anthropogenic-CO2-induced global warming. Not buying into this scenario without more solid evidence to support it, however, the five scientists decided to test this concept further by exploring the heat tolerance and possible physiological plasticity of the Arctic collembolan, Megaphorura arctica, from Svalbard, and the Antarctic midge, Eretmoptera murphyi, from Antarctica's Signy Island. And what did they learn in doing so?

The five scientists - hailing from the United Kingdom, Malaysia and New Zealand - say their data demonstrate "considerable heat tolerance in both species, with upper lethal temperatures ≥35°C (1 hour exposure), and tolerance of exposure to 10 and 15°C exceeding 56 days," which tolerance, as they indicate, is far beyond that required in either of the two species' current environments. And they say there is also evidence to suggest that "E. murphyi can recover from high-temperature exposure and that M. arctica is capable of rapid heat hardening."

As for their final take on the subject, Everatt et al. write that M. arctica and E. murphyi "have the physiological capacity to tolerate current environmental conditions, as well as future warming." And they say that "if the features they express are characteristically more general, such polar terrestrial invertebrates will likely fare well under climate warming scenarios." In fact, they say "it is becoming increasingly clear that many terrestrial invertebrates resident in the Antarctic and Arctic are remarkably heat tolerant," citing Block et al. (1994), Hodkinson et al. (1996), Deere et al. (2006), Sinclair et al. (2006), Slabber et al. (2007) and Everatt et al. (2013). And even more amazing is the possibility, as they phrase it, that "climate warming might alleviate the stresses of living in a low-temperature environment and benefit some polar species," as has been suggested by the findings of Convey (2006, 2011), and Bale and Hayward (2010).

References
Bale, J.S. and Hayward,S.A.L. 2010. Insect over-wintering in a changing climate. Journal of Experimental Biology 213: 980-994.

Block, W., Webb, N.R., Coulson, S., Hodkinson, I.D. and Worland, M.R. 1994. Thermal adaptation in the Arctic collembolan Onychiurus arcticus (Tullberg). Journal of Insect Physiology 40: 715-722.

Convey, P. 2006. Antarctic climate change and its influences on terrestrial ecosystems. In: Bergstrom, D.M., Convey, P. and Huiskes, A.H.L. (Eds.). Trends in Antarctic Terrestrial and Limnetic Ecosystems: Antarctica as a Global Indicator. Springer, Dordrecht, Netherlands, pp. 253-272.

Convey, P. 2011. Antarctic terrestrial biodiversity in a changing world. Polar Biology 34: 1629-1641.

Deere, J.A., Sinclair, B.J., Marshall, D.J. and Chown, S.L. 2006. Phenotypic plasticity of thermal tolerances in five oribatid mite species from sub-Antarctic Marion Island. Journal of Insect Physiology 52: 693-700.

Everatt, M.J., Convey, P., Worland, M.R., Bale, J.S. and Hayward, S.A.L. 2013. Heat tolerance and physiological plasticity in the Antarctic collembolan, Cryptopygus antarcticus, and the mite, Alaskozetes antarcticus. Journal of Thermal Biology 38: 264-271.

Hodkinson, I.D., Coulson, S.J., Webb, N.R. and Block, W. 1996. Can high Arctic soil microarthropods survive elevated summer temperatures? Functional Ecology 10: 314-321.

Sinclair, B.J., Terblanche, J.S. and Scott, M.B. 2006. Environmental physiology of three species of springtail at Cape Hallett, North Victoria Land, Antarctica. Journal of Insect Physiology 52: 29-50.

Slabber, S., Worland, M.R., Leinaas, H.P. and Chown, S.L. 2007. Acclimation effects on thermal tolerances of springtails from sub-Antarctic Marion Island: indigenous and invasive species. Journal of Insect Physiology 53: 113-125.

Posted 29 October 2014