The response of Daphnia magna Straus to long-term exposure to simulated geomagnetic storms

The capability of Daphnia magna to adapt to artificial low-frequency magnetic fields via a maternal effect has been demonstrated previously. The current study assessed the possibility of a maternal effect in response to simulated natural geomagnetic fluctuations. D. magna lines were exposed to simulated geomagnetic storms for two, five, and eight sequential generations. Evaluations were conducted on the 3rd, 6th, and 9th generations of daphnids from experimental and control lines in order to determine the period required for the formation of an adaptive maternal effect. The evaluations showed that larger offspring were produced when maturation and reproduction occurred under the same conditions as those in which the Daphnia had lived in for generations. These observations suggest a manifestation of an adaptive maternal effect occurs in response to long-term exposure to simulated geomagnetic storms. Ecological relevance of geomagnetic storms to natural populations of daphnids is discussed.