Evaluation of changes in diatom mobility after exposure to 16-Hz electromagnetic fields

The effect of a 16-Hz electromagnetic field on the mobility of the diatom Amphora coffeaformis was examined on agar plates that contained no added calcium and also on agar plates containing 0.25 or 2.5 mM exogenous Ca2+. Exposure conditions consisted of an ac field of 16 Hz with an amplitude of 20.9 microT parallel to the horizontal component of the dc field (BH = 20.9 microT, where BV = 0). To assess results, the percentage of diatoms that moved a distance greater than their body length was determined. We observed the field-associated increase in diatom motion at 0.25 mM Ca++, which was previously reported in the literature. Although the magnitude of the effect at 16 Hz was significant, the percentage of cells that moved was not sufficiently reproducible to allow examination for frequency dependence.