Diatom motility and low frequency electromagnetic fields - A new techniquein the search for independent replication of results

The hypothesis that exposure to a certain combination of static and alterna ting electromagnetic fields (EMFs) results in an increase in motility of th e marine diatom Amphora coffeaeformis was tested. Diatom motility in three strains of A. coffeaeformis was positively correlated with extracellular ca lcium ion (Ca2+) concentration. The test apparatus consisted of two pairs o f Helmholtz coils supported around the stage of a microscope linked to a vi deo recorder and monitor. This system allowed real-time in vivo recordings of diatom speed under EMF and control exposures. The EMFs were calculated a t calcium resonance values, previously found to cause enhanced motility. Co mputerised image analysis was used to calculate the distance moved by indiv idual diatoms in 2-min periods before, during and after EMF or sham-EMF (co ntrol) exposure. The addition of EMF caused no significant increase in diat om motility. The results are discussed in relation to the use of diatom mot ility to measure EMF exposure effects. (C) 1999 Wiley-Liss, Inc.