Introducing energy into marine environments: A lab-scale static magnetic field submarine cable simulation and its effects on sperm and larval development on a reef forming serpulid*

Non-chemical sources of anthropogenic environmental stress, such as artificial lights, noise and magnetic fields, are still an underestimate factor that may affect the wildlife. Marine environments are constantly subjected to these kinds of stress, especially nearby to urbanized coastal areas. In the present work, the effect of static magnetic fields, associated with submerged electric cables, was evaluated in gametes and early life stages of a serpulid polychaete, namely Ficopomatus enigmaticus. Specifically, biochemical/physiological impairments of sperm, fertilization rate inhibition and incorrect larval development were assessed. We evaluated differences between two selected magnetic field induction values (0.5 and 1 mT) along a range of exposure times (30 min-48 h), for a sound evaluation on this species. We found that a magnetic induction of 1 mT, a typical value that can be found at distance of tens of cm from a submerged cable, may be considered a biologically and ecologically relevant for sessile organisms and for coastal environments more generally. This value exerted statistically significant effects on membranes, DNA integrity, kinetic parameters and mitochondrial activity of sperm cells. Moreover, a significant reduction in fertilization rate was observed in sperm exposed to the same magnetic induction level (1 mT) for 3 h, compared to controls. Regarding early larval stages, 48-h exposure did not affect the correct development. Our results represent a starting point for a future focus of research on magnetic field effects on early life stages of aquatic invertebrates, using model species as representative for reefforming/encrusting organisms and ecological indicators of soft sediment quality.

Automated summary

Non-chemical anthropogenic stressors, such as artificial lights, noise, and magnetic fields, underestimated their effects on wildlife, especially in marine environments near urbanized coastal areas. This study evaluated the effects of static magnetic fields from submerged electric cables on the gametes and early life stages of Ficopomatus enigmaticus, a serpulid polychaete. Magnetic fields of 1 mT, commonly found near submerged cables, showed significant impacts on sperm cells' membranes, DNA integrity, kinetic parameters, and mitochondrial activity. Fertilization rate was also reduced after 3 hours of exposure to this magnetic induction level. Our findings provide a starting point for future research on magnetic field effects on early life stages of aquatic invertebrates and their role as ecological indicators of sediment quality.