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Understanding the effects of electromagnetic field emissions from Marine Renewable Energy Devices (MREDs) on the commercially important edible crab, Cancer pagurus (L.)

Kevin Scott1, 2*, Petra Harsanyi1 and Alastair R. Lyndon2
  • 1 St Abbs Marine Station, United Kingdom
  • 2 Heriot-Watt University, United Kingdom

The predicted decline in non-renewable energy sources in future decades indicates the need for alternative renewable energy sources. Due to reduced planning constraints, lack of inexpensive land near major population centres, and perceived aesthetic problems with many renewable energy structures, there is increasing pressure to move potential locations offshore. With the rapid increase in Marine Renewable Energy Devices (MREDs) worldwide, there is a clear need for the implications to be properly assessed with regards to current ecological status and potential future consequences. Proposed sites and developments are based on current knowledge and assessments of the local environment, despite relatively little being known about the ecological effects of such developments on marine benthic organisms. Electromagnetic fields (EMF) originate from both anthropogenic (telecommunication cables, power cables, MREDs) and natural (Earth’s natural geomagnetic field) sources. It has been shown that industry-standard AC (Alternating Current) cables can be effectively insulated to prevent electric field (E-field) emissions but not magnetic field (B-field) emissions1. Standard cable configurations combined with the existing B-field creates induced electromagnetic fields (iEM fields). Many marine animals can detect electric and magnetic fields and utilize them in such important life processes as movement, orientation and foraging2. Several decapod crustaceans are known to be magneto sensitive, yet information available on the effects of electromagnetic fields emitted from MREDs is scarce3,4. The European edible crab, Cancer pagurus (L.), is found throughout Western Europe from Norway to northern France. They are commonly found from the shoreline to offshore depths around 90m. They are a heavily exploited commercial species with the present UK and Ireland annual catch around 34,600 tonnes (Bannister 2009). There is a high probability that this species will encounter sub-sea power cables resulting in increased EMF exposures, potentially leading to stress responses. In this study the effects of simulated electromagnetic fields (EMF), emitted from sub-sea power cables, on the commercially important decapod, edible crab (Cancer pagurus), were assessed. Crabs were obtained from the St Abbs and Eyemouth Voluntary Marine Reserve (North Sea), and transported to St Abbs Marine Station. Crabs were kept in 1000L flow through tanks supplied with raw seawater with ambient sea temperature and natural photoperiod for a minimum acclimation of one week. Crabs were exposed for 24-hours to static EMFs at strengths of 2.8mT and 40mT to correspond with the expected, although highly variable, levels on the surface of a sub-sea power cable and correspond to those in previous studies5. The EMF was produced by electric solenoid magnets (24V) placed underneath the experimental tanks or by Helmholtz coil generating a uniform electromagnetic field area around the experimental tanks. Stress related physiological parameters were measured (L-Lactate, D-Glucose, Haemocyanin and respiration rate) along with behavioural and response parameters (antennular flicking, activity level, attraction/avoidance, shelter preference and time spent resting/roaming). Exposure to electromagnetic fields, of the strength predicted around sub-sea cables, had significant physiological effects on Cancer pagurus and changed their behaviour. Crabs showed a clear attraction to EMF exposed shelter (69%) compared to control shelter (9%) and significantly reduced their time spent roaming by 21%. This suggests that the natural roaming behaviour, where individuals will actively seek food and/or mates has been overridden by an attraction to the source of the EMF. When given the choice between a shelter exposed to EMF and one without exposure, the crabs were always drawn to the EMF. These results predict that in benthic areas surrounding MREDs, where there is increased EMFs, there will be an increase in the abundance of Cancer pagurus present. EMF disrupted the circadian rhythm of haemolymph L-Lactate and D-Glucose levels. Melatonin levels in several species have been found to be affected by EMF exposure6,7. This suggests that EMF exposure could affect crustaceans on a hormonal level. This potential aggregation of crabs around benthic cables and the subsequent physiological changes brought about by EMF exposure, is a cause for concern. Berried female Edible crabs move offshore and spend 6-9 months, buried with minimal movement and lower feeding rates8. Given this species’ proven attraction to EMF sources, incubation of the eggs may take place around areas with increased EMF emissions. Long term studies are needed to investigate the effects of chronic EMF exposure along with the effects of EMF on egg development, hatching success and larval fitness. This study shows that the impact of EMF on crustaceans must be considered when planning MREDs. With the recent large scale renewable energy developments, it is clear more research is needed to reduce uncertainty of the environmental effects of these activities on benthic marine species, particularly on other commercially and ecologically important decapod crustaceans. These knowledge gaps need to be addressed before the implementation of the many approved wind farm sites around the UK to help mitigate an ever growing problem.

Acknowledgements

Work was conducted at St Abbs Marine Station, a private charity on the Scottish East coast. Funding for this study was received from the Nesbitt-Cleland Trust. The help of numerous volunteers is greatly acknowledged.

References

1. Bochert, R. and Zettler, M.L., 2006. Effect of electromagnetic fields on marine organisms. In Offshore Wind Energy (pp. 223-234). Springer, Berlin, Heidelberg.
2. Boles, L.C. and Lohmann, K.J., 2003. True navigation and magnetic maps in spiny lobsters. Nature, 421(6918), p.60.
3. Fernie, K.J. and Bird, D.M., 2001. Evidence of oxidative stress in American kestrels exposed to electromagnetic fields. Environmental research, 86(2), pp.198-207.
4. Gill, A. B. 2005. Offshore renewable energy: ecological implications of generating electricity in the coastal zone. Journal of Applied Ecology, 42(4), 605-615.
5. Hutchison, Z.L., Sigray, P., He, H., Gill, A.B., King, J. and Gibson, C., 2018. Electromagnetic Field (EMF) Impacts on Elasmobranch (shark, rays, and skates) and American Lobster Movement and Migration from Direct Current Cables. Sterling (VA): US Department of the Interior, Bureau of Ocean Energy Management. OCS Study BOEM, 3.
6. Naylor, J.K., Taylor, E.W. and Bennett, D.B., 1997. The oxygen uptake of ovigerous edible crabs (Cancer pagurus)(L.) and their eggs. Marine & Freshwater Behaviour & Phy, 30(1), pp.29-44.
7. Shields, M.A. and Payne, A.I. eds., 2014. Marine renewable energy technology and environmental interactions. Springer.
8. Woodruff, D.L., Ward, J.A., Schultz, I.R., Cullinan, V.I. and Marshall, K.E., 2012. Effects of electromagnetic fields on fish and invertebrates. US Department of Energy.

Keywords: Cancer pagurus, Edible crab, electromagnetic field, Environmental stressor, Marine renewable energy

Conference: IMMR'18 | International Meeting on Marine Research 2018, Peniche, Portugal, 5 Jul - 6 Jul, 2018.

Presentation Type: Poster Presentation

Topic: Fisheries and Management

Citation: Scott K, Harsanyi P and Lyndon AR (2019). Understanding the effects of electromagnetic field emissions from Marine Renewable Energy Devices (MREDs) on the commercially important edible crab, Cancer pagurus (L.). Front. Mar. Sci. Conference Abstract: IMMR'18 | International Meeting on Marine Research 2018. doi: 10.3389/conf.FMARS.2018.06.00105

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Received: 26 Apr 2018; Published Online: 07 Jan 2019.

* Correspondence: Mr. Kevin Scott, St Abbs Marine Station, St Abbs, Berwickshire, TD14 5PW, United Kingdom, kevin.scott@marinestation.co.uk