In 2014, The University of Rhode Island and key partners were contracted by the Bureau of Ocean Energy Management (BOEM)to conduct a two-year study entitled "Electromagnetic Field (EMF) Impacts on Elasmobranch (sharks, rays, and skates) and American Lobster Movement and Migration from Direct Current Cables." The BOEM-URI project had five major components:
- A synthesis of existing information published subsequent to the report entitled " Effects of EMFs from Undersea Power Cables on Elasmobranchs and Other Marine Species" (Normandeau et al., 2011) for BOEM on EMF and the potential effects on marine species;
- Field surveys to characterize the EMF from two high voltage direct current (HVDC) cables; the Cross Sound Cable (CSC) and the Neptune Cable;
- A computer model to predict the EMF generated by HVDC cables and a comparison of EMF model predictions with EMF field measurements for validation and to determine if the model could be extrapolated to higher capacity cables that are likely to be installed in the future;
- A statistically robust field experiment that would detect potential effects of EMF from HVDC cables on the movements of marine species (American lobster, Homarus americanus and Little skate, Leucoraja erinacea) of concern; and
- An integration, interpretation and evaluation of the multidisciplinary findings.
Prepared under BOEM Contract M14PC00009
A comprehensive literature review was conducted as part of the BOEM-URI project, in order to synthesize the knowledge gained since the Normandeau, et al., (2011) report. This review revealed that the understanding of EMF and interactions with marine organisms had improved; however, significant gaps remained in the knowledge base.
Following the literature review, the goals of the URI-BOEM project were to address key knowledge gaps by collecting data on subsea cable EMF emissions for validating models, and to provide the context for assessing whether there were effects of EMF from HVDC cables on the sensitive species of interest.
- The EMF associated with HVDC cables was specifically measured in situ by the sensitive SEMLA device, which highlighted the presence of unexpected AC components in the EMF emissions for both the CSC and Neptune Cable. DC and AC magnetic fields extended out to 5 and 10m from either side of the cables respectively, whereas the AC electric fields extended out to 100mfrom either side of the cable. On the other hand, the AC fields of the HVAC sea2shore cable were generally ten-fold lower than model predictions.
- The COMSOL model provided good estimates of the magnitude and shape of DC fields from HVDC cables, and is scalable to higher capacity cables.
- The novel acoustic telemetry approach worked well to track movements of marine animals with much higher accuracy (<5cmfor beacon tag) and frequency (<3 second interval) of recorded positions than previous studies which were limited to an accuracy of <1m and frequency of <3minutes.
- The field-deployed animal enclosures and acoustic telemetry method developed and fully tested in this study successfully allowed the collection of in situ, high frequency three-dimensional positional data on individual animals at both an experimental treatment enclosure on the power cable and an enclosure at a control site for reference.
- Homarus americanus (the American lobster) exhibited a statistically significant but subtle change in behavioral activity when exposed to the EMF of the HVDC cable, which operated at a constant power of 330MW (1175Amps). At the treatment enclosure (B), lobsters were on average closer to the seabed and exhibited a higher proportion of changes in the direction of travel (termed large turns), when second in the sequence, compared to the control enclosure (A). They also made more use of the central space of the treatment enclosure (B) compared to the control (A).
- Leucoraja erinacea (the Little skate) exhibited a strong behavioral response to the EMF from the CSC. The cable was powered for 62.4% of the study and most frequently transmitted electrical current at 16 Amps (at 0MW, 37.5% of time), 345 Amps (100MW, 28.6%) and 1175 Amps (330MW, 15.2%). In comparison to the control enclosure (A), the skates at the treatment enclosure (B) traveled further but at a slower speed, closer to the seabed and with an increased proportion of large turns which suggested an increase in exploratory activity and/or area restricted foraging behavior. The increased distance traveled and increased proportion of large turns was associated with the zone of high EMF (>52.5μT, i.e. above the Earth’s magnetic field) where they were more frequently recorded and spent more time.
- For both species, the behavioral changes have biological relevance in terms of how the animals will move around and be distributed in a cable EMF zone. The EMF associated with the CSC did not constitute a barrier to movements across the cable for either lobsters or skates.
Hutchison, Z.; Sigray, P.; He, H.; Gill, A.; King, J.; Gibson, C. (2018). Electromagnetic Field (EMF) Impacts on Elasmobranch (shark, rays, and skates) and American Lobster Movement and Migration from Direct Current Cables. Report by University of Rhode Island, Cranfield University, and FOI (Swedish Defence Research Agency). pp 254.