The effects of a magnetic field (1, 3 and 5 mT), applied during short- (1, 3, 5, 30 and 60 minutes) and long-term (from the beginning of embryogenesis) exposure, on melanophores of the European whitefish, Coregonus lavaretus and vendace, Coregonus albula, were investigated. Short-term magnetic field exposure effects on the behaviour of melanophores at the stage when the eye and body pigment on whitefish and vendace were distinctly visible in the embryos. The short-term embryo exposure to the magnetic fields induced the pigment of the body cells to move to the central parts of the cells. In the control, we did not observe displacement of the pigment within the melanophores. The long-term exposure to the magnetic field was found to delay the pigment appearance in the eyeballs and on the body of embryos of both investigated species. The number of melanophores in the body of embryos exposed to the magnetic fields was lower than that in the control. The pigment showed an increasing tendency to concentrate in individual embryonic and larval cells with increasing magnetic field strength. Melanophore index in embryos and larvae of whitefish and vendace was found to differ significantly between the control and all the magnetic field treatments.
Our results can be extrapolated to other organisms and will allow us to broaden the knowledge on pigment cell magnetoreception in vertebrates.