The response of European Daphnia magna Straus and Australian Daphnia carinata King to changes in geomagnetic field

Abstract

This study investigates the effects of lifelong exposure to reversed geomagnetic and zero geomagnetic fields (the latter means absence of geomagnetic field) on the life history of Daphnia carinata King from Australia and Daphnia magna Straus from Europe. Considerable deviation in the geomagnetic field from the usual strength, leads to a decrease in daphnia size and life span. Reduced brood sizes and increased body length of neonates are observed in D. magna exposed to unusual magnetic background. The most apparent effects are induced by zero geomagnetic field in both species of Daphnia. A delay in the first reproduction in zero geomagnetic field is observed only in D. magna. No adaptive maternal effects to reversed geomagnetic field are found in a line of D. magna maintained in these magnetic conditions for eight generations. Integrally, the responses of D. magna to unusual geomagnetic conditions are more extensive than that in D. carinata. We suggest that the mechanism of the effects of geomagnetic field reversal on Daphnia may be related to differences in the pattern of distribution of the particles that have a magnetic moment, or to moving charged organic molecules owing to a change in combined outcome and orientation of the geomagnetic field and Earth's gravitational field. The possibility of modulation of self-oscillating processes with changes in geomagnetic field is also discussed.

Keywords::

• Reversal of geomagnetic field
• Zero geomagnetic field
• Daphnia magna; Daphnia carinata

Acknowledgements

We are grateful to Boris Klain and Oleg Zotov (Shmidt's Institute of Physics of the Earth RAS) for their help with magnetic field equipment. Special thanks for the delivery of D. carinata go to Vladimir Tchougounov (I.D. Papanin Institute for Biology of Inland Waters RAS). The authors also thank Dmitry F. Pavlov (I. D. Papanin Institute for Biology of Inland Waters RAS) and Kelsey Schlee (Michigan State University) for their help with English version of the manuscript. The reported study was partially supported by RFBR (project No. 11-04-01252 s) and FTP “Scientific and Scientific-Pedagogical Personnel of the Innovative Russia” (agreement No. 8594).

Declaration of Interest The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Notes

¹ A negative value of GMF intensity denotes that the magnetic lines of force are directed outwards from the Earth, a positive value of GMF intensity denotes that the magnetic lines of force are directed towards the Earth.