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Reviewed by: Zoë Hutchison

Last Update: January 18th, 2020

At the 17th Ronald C. Baird Sea Grant Science Symposium Session #5: Effects of Noise and EMF on Benthic Communities, Zoë Hutchison (Research Fellow, University of Rhode Island) explained how EMF affects marine animals.

Natural electromagnetic fields (EMFs) provide ecologically important cues to marine animals in a variety of ways i.e. the locating of important resources, predator-prey interactions, communication and finding mates. At the very core of this interaction, is the animals’ ability to understand the electromagnetic environment through their sensory biology and abilities.

This is relevant to offshore wind farms because the subsea cables that connect the turbines and those that connect the wind farms to their onshore grid, emit EMFs. It is important to understand how various species interact with EMFs and how the artificial EMFs change the natural fields.

In terms of magnetoreception (an organism’s ability to detect a magnetic field), there is not yet a full understanding of the associated physiology; but, we do know that this ability exists within both marine and terrestrial species. Animals with this sensory ability are described as having either a magnetic map sense or a magnetic compass sense, to allow them to derive positional and directional information from their surrounding environment.

There is a greater understanding of electroreceptive species (those with a biological ability to perceive natural electrical stimuli) and the organs involved in the process. There is likely a degree of variation among the different species with this electrosensory ability which may also allow species to respond indirectly to magnetic cues.  Some species may have both magnetoreceptive and electroreceptive physiology. 

Hutchison provided a very brief overview of some of the knowledge relating to effects and responses to EMF for the following benthic species, noting that the studies were very varied in their exposure types, intensities and methods. Generalizations should be avoided and readers are encouraged to consult the literature cited in the presentation. 

Examples of Studies Exploring Responses of Marine Species to Electromagnetic Fields
Bacteria	Some species are magnetotactic and so may respond to EMF. New studies suggest magnetic fields may influence biofilm development.
Polychaetes	Changes in polychaete behavior in response to magnetic fields
Bivalves	Exposure to magnetic fields resulted in changes in immunological pathways or genotoxic and cytotoxic responses in bivalves (baltic clams and blue mussels)
Lobsters	Adult American lobsters changed its exploratory behavior in response to cable EMF in a mesocosm experiment. Juvenile European lobsters exhibited no response to a gradient of magnetic field in an aquarium study
Crabs	In aquarium studies, edible crabs were attracted to shelters exposed to magnetic fields and experienced hormonal changes in response to stronger magnetic fields.  Other field studies in the USA demonstrated that crabs could cross cables and their catchability was not affected.
Catsharks (Elasmobranch, cartilaginous fish)	Aquarium studies of catsharks displayed the ability to differentiate between AC and DC fields but did not differentiate between artificial and natural fields.
Skates and Rays (Elasmobranchs)	Change their exploratory and foraging behavior in response to a cable EMF in mesocosm experiments.
Salmon	Salmon smolts could pass a cable EMF and continued their migration, a degree of misdirection was detected
Eels	European eels were able to cross a cable but slowed down. There is ongoing work in this area at URI.

Hutchison describes these findings as a patchwork of information as the data set covers a limited number of species and is derived from various methods of collection. She indicated that we need to question how the research available is relevant to and can be used in the context of offshore wind. She says to advance our knowledge base, more research is needed to determine: 1) how species encounter and perceive cable EMFs throughout their lifetime and 2) how cable EMFs are present to marine species and vary with cable properties. Advancing this knowledge base will require a multidisciplinary approach and stakeholder involvement. 

Hutchison has recently published a brief review on the topic in Oceanography; https://tos.org/oceanography/article/the-interaction-between-resource-species-and-electromagnetic-fields-associated-with-electricity-production-by-offshore-wind-farms