Magnetic fields produced by subsea high-voltage direct current cables reduce swimming activity of haddock larvae (Melanogrammus aeglefinus)

Abstract

High Voltage Direct Current (HVDC) subsea cables are used to transport power between locations and from/to near-shore and off-shore facilities. HVDC cables produce magnetic fields (B-fields) that could impact marine fish. Atlantic haddock (Melanogrammus aeglefinus) is a demersal fish that is at risk of exposure to anthropogenic B-fields. Their larvae drift over the continental shelf, and use the Earth's magnetic field for orientation during dispersal. Therefore, anthropogenic MFs from HVDC cables could alter their behavior. We tested the behavior of 92 haddock larvae using a setup designed to simulate the scenario of larvae drifting past a B-field in the intensity range of that produced by a DC subsea cable. We exposed the larvae to a B-field intensity ranging 50-150 μT in a raceway tank. Exposure to the B-field did not affect the spatial distribution of haddock larvae in the raceway. Larvae were categorized by differences in their exploratory behavior in the raceway. The majority (78%) of larvae were non-exploratory, and exposure to the artificial B-field reduced their median swimming speed by 60% and decreased their median acceleration by 38%. There was no effect on swimming of the smaller proportion (22%) of exploratory larvae. These observations support the conclusion that swimming performance of non-exploratory haddock larvae would be reduced following exposure to B-field from HVDC cables. The selective impact on non-exploratory individuals, and the lack of impact on exploratory individuals, could have population-scale implications for haddock in the wild.

Magnetic fields generated by submarine power cables have a negligible effect on the swimming behavior of Atlantic lumpfish (Cyclopterus lumpus) juveniles

“…The observed MF-related decrease in swimming speed of lumpfish was smaller (this study: 16%) than that observed in Atlantic haddock larvae ( Melanogrammus aeglefinus ) (60%) exposed to slightly lower intensities ( Cresci et al, 2022a ; 150 µT, this study: ~200 µT). European eel ( Anguilla anguilla ) also reduced their swimming speed in the vicinity of a submarine power cable ( Westerberg & Lagenfelt, 2008 ).…”

Fit-for-Purpose Information for Offshore Wind Farming Applications—Part-I: Identification of Needs and Solutions

“…Electromagnetic fields (EMFs): submarine cables and electrical infrastructure associated with OWFs emit electromagnetic fields and potentially impact marine creatures [54]. Different fish species have shown different sensitivity to changes in EMF by either showing changes in behavior [55] or no reaction [56]. The information products required in this application are EMF levels and their potential effects on migratory patterns, behavior, and sensory systems of marine species.…”

Fit-for-Purpose Information for Offshore Wind Farming Applications—Part-II: Gap Analysis and Recommendations

“…Furthermore, the installation of wind turbines and the associated infrastructure (e.g., cables and substations) can cause physical habitat alteration and loss. For example, the installation of OWF can disrupt the seabed and benthic ecosystems and have an impact on the behavior of the marine species via the change in the electromagnetic fields, which is caused by undersea cables transmitting electricity from OWFs [111,112]. Furthermore, the currents around monopiles in OWFs increase turbulent mixing, potentially leading to the break-up of stratification [113,114], increased turbidity [115], and changes in primary production [6,116,117].…”