Response of aquatic protists to electric field exposure

Purpose: To test the effects of short-term exposure of aquatic organisms to electric field (EF) with negligible magnetic component. Materials and methods: We built a plate capacitor that served as a source of EF of strengths that can be found in nature near transmission lines. We exposed two cultured protist species Euglena viridis and Paramecium caudatum to EFs for 24hours and monitored their abundance, morphology, intracellular superoxide anion (by dihydroethidium [DHE]), hydrogen peroxide by (H2DCF) and lipid peroxidation (MDA) contents, catalase (CAT) and superoxide dismutase (SOD) activity. Results: We found that even short-term exposure to low strength EF causes changes in population abundance, morphology and oxidative stress response in both species. As the EF strength increased, abundance of both species decreased. However, at weaker EFs, fission rates were seemingly promoted. We noted a decrease in size in both organisms in directions perpendicular to their fission planes correlated with EF strength. DHE and H2DCF fluorescence intensity and SOD activity were higher in organisms exposed to the stronger EFs. Conclusions: We suggest that the electric component of the field, rather than the magnetic, is the main cause of all the noted effects. As a result, aquatic organisms should be given greater importance in studies assessing the effects of EMFs in spite of the attenuating effects of water to EF strengths.