TY - THES
TI - The potential impacts of submarine power cables on benthic elasmobranchs
AU - Orr, M
AB - Offshore renewable energy developments are becoming increasingly popular to meet the growing global demand for renewable energy.  Marine sources of renewable energy, and other power transmission requirements, use submarine power cables that are either alternating current (AC) or direct current (DC).  Both have the potential to generate weak electromagnetic fields (EMFs) within the elasmobranch sensitivity range.  Thus the question arises: do submarine cables adversely affect elasmobranchs?  To help address this question, the effects of EMFs associated with a 50 Hz 75 amp (A) AC power cable, a 30 A DC cable and a 198 A DC cable were studied through a novel series of laboratory experiments, with and without seawater flow over the cables.  Experiments used two benthic elasmobranch species, the New Zealand eagle ray (Myliobatis tenuicaudatus Hector, 1877) and New Zealand carpet shark (Cephaloscyllium isabellum Bonnaterre, 1788).  Eagle rays showed no response to the active 30 A DC cable 51.8% of the time in seawater flow, and 85.1% of the time in no seawater flow.  In these experiments, the cables were above the tank floor and responses towards active and inactive cables were similar, so were likely triggered by visual and tactile cues.  An improved experimental design was developed to remove these confounding factors, introduce AC fields, and increase EMF strengths to more closely simulate field strengths.  Under these conditions, the sharks showed no response to the active AC cable an overwhelming 98% of the time. In response to the 198 A DC cable, they investigated the active cable zone 8.1% of the time but still showed no response towards the active cable 90.9% of the time.  The sharks habituated to the 198 A DC cable within the first five minutes of an experiment.  Based on these results, it is concluded that submarine AC cables of a similar specification will have little effect and are unlikely to impact benthic elasmobranchs.  Based on the rapid habituation shown by the sharks, the small effect prompted by 198 A DC cables is also not expected to translate into an impact, though further research into other cable specifications and study species is recommended. 
DA - 2016/01//
PY - 2016
SP - 170
PB - University of Auckland
UR - https://researchspace.auckland.ac.nz/bitstream/handle/2292/30773/whole.pdf?sequence=2
LA - English
M3 - PhD Thesis
KW - Marine Energy
KW - Wind Energy
KW - EMF
KW - Fish
KW - Demersal Fish
ER -