Introduction
Harnessing energy from the wind is becoming an increasingly important research field, particularly in offshore environments. In addition, combining energy production with fish farming under common infrastructures has been highlighted as a priority at a European level. A challenge in that regard is that the effects of electromagnetic fields (EMF) generated by the wind turbines on the farmed species are largely unknown. Yet, studies on several species indicate that the presence of strong EMF may affect, among others, the embryonic development, circadian rhythm, metabolism, orientation, and migration
of fish. In this study we investigate effects of EMF of industrial intensity on the growth performance, metabolism, and behavior of an important Mediterranean aquaculture fish, the European seabass (Dicentrarchus labrax).
Materials and methods
A trial was performed in the Recirculating Aquculture System of HCMR (Greece) where juvenile European seabass of approximately 200 g were subjected to an EMF of 20 mT for three months. Growth performance was monitored monthly (weight measurements) while towards the end of the trial an intermittent flow respirometer was used (N = 15 per group ) to determine the Standard Metabolic Rate . Additional were performed on E. seabass fingerlings (approximately 2 g) using a T-maze setup in order to investigate behavioral effects relating to swimming and directional orientation. These tests were performed with the aid of a Helmholtz coil (Fig 1. ) which generates a uniform EMF at a strength of 10mT .
Results
There were no significant differences between the control and the EMF groups in growth performance of the fish. Both groups exhibited normal growth and increased in weight by 150 g over the trial period. Similarly, results from respirometry suggest that the EMF did not significantly affect their basal metabolic requirements; SMR showed minimal differences between groups exhibiting values between 85.1 – 88.4 mg kg-1 h-1. However, the initial results using the T-maze (Fig 1.) indicate that the EMF may significantly affect some behavioral traits in E. seabass. In particular, application of EMF appeared to increase the prevalence of ‘freezing behavior’ (assigned to fish that remain immobile ) from 15% to 25% in the tested fish. Moreover, preliminary analysis indicates that while the control group showed uniform distribution towards the south-north axis, the EMF may exhibit a preference for the magnetic South.
Conclusion
In this study we investigated the effects of EMF on several biological aspects of an important aquaculture species. Our results indicate that under industrial EMF intensity, the growth performance and basal metabolism of E. seabass are no t significantly affected. In turn, this is a promising outcome for promotion of multi-use platforms combining fish farming with wind energy production. However, preliminary analysis indicates possible effects on the behavior of young fish which requires further investigation before management and policy recommendations can be made.
References
Formicki, K., Korzelecka-Orkisz, A., Tański, A., 2019. Magnetoreception in fish. Journal of Fish Biology 95, 73–91. https://doi.org/10.1111/jfb.13998
Newton, K.C., Kajiura, S.M., 2020. The yellow stingray (Urobatis jamaicensis) can use magnetic field polarity to orient in space and solve a maze. Mar Biol 167, 36. https://doi.org/10.1007/s00227-019-3643-9
Acknowledgement
This research has been co-financed by the European Regional Development Fund of the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship, and Innovation, (MagnetoFish , project code: T6YBΠ-00317).