The effect of static magnetic field on melanophores in the sea trout (Salmo trutta m. trutta Linnaeus, 1758) embryos and larvae

Abstract

Magnetic field affects many living organisms, fishes included. The fish reactions are observed from the early stage of development, during embryogenesis and larval period, and into adult stage. Magnetic field affects, among other processes, water exchange in the eggs, embryo heart rate and respiration, directional reactions and spatial orientation. The few papers in this field published so far present melanophores morphology and development. Melanophores developing in embryos and in newly hatched sea trout (Salmo trutta m. trutta L.) larvae which had been incubated and kept under optimal conditions constituted the material for the study. The effect of static, generated magnetic field of intensity of 1, 3 and 5 mT on melanophores of sea trout embryos and larvae was studied. The control setting was kept under geomagnetic field. The appearance of melanophores in the trout embryos exposed to magnetic field was delayed. The number of melanophores was smaller, and the movement of melanin within the melanophores, visible as aggregation of pigment in the cells. Static magnetic field of relatively low intensity influences the reaction of melanophores of developing trout embryos and newly hatched larvae. Most probably, magnetite (Fe3O4) compounds, detected in many fish species, mainly migratory fishes such as trout, are responsible for such behaviour of melanophores.Highlights Static magnetic field delays the appearance of melanophores in the trout embryos and larvae. The largest aggregation of melanin in melanophores was found in larvae incubated in a 5 mT magnetic field. The largest number of melanophores was found in the embryos incubated in the geomagnetic field.

Keywords

• fish
• sea trout
• pigment cell
• melanophore index
• magnetic field