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impact of noise emissions on marine organisms that
inhabit or migrate through the area. (See Annexe 1,
section 2.3. for more details).
Cables transmitting power between WTC devices
and to the mainland may have an effect on marine
organisms, such as migratory fish, elasmobranches,
crustaceans and marine mammals that use magnetic
fields for navigation or finding prey (Kalmijn,
2000, Gill et al., 2005, Öhman et al 2007, Gill et
al. 2009). No significant effects on marine organisms
from exposure to electromagnetic fields have
been established (Bochert and Zettler, 2004; Gill et
al., 2005; Gill et al. 2009), but further research is
needed to investigate how the relatively dense networks
of cables within WTC parks may affect navigation
and foraging by electrosensitive species. (See
Annexe 1, Section 2.4. for more details)
Figure 5: Example of a wave activated body, the point absorber (Seabased Ltd).
Studies on collision risks between marine organisms,
such as mammals and fish, and submerged
structures are rare (Gill, 2005). For wave power,
it appears unlikely that installations would result
in large numbers of collision fatalities to marine
organisms. However, fish and mammals may be
harmed colliding with or entangling in mooring
chains (Wilson et al. 2007). Some concerns that tidal
fences and turbines blocking channels may harm or
hamper migration by wild life have, on the other
hand, been raised (e.g. Pelc & Fujita 2002, Inger
et al. 2009). It is not certain that the slow moving
turbines cause any impacts, as no effects on either
fish or water movement were recorded in conjunction
with a prototype built by Nova Energy, in the St.
Lawrence Seaway (Blue Energy Canada 2001).
To decrease collision fatalities and barrier effects
on fish, developers could construct systems where
the space between the caisson wall and rotor foil
is large enough for fish to pass through (e.g. Pelc
& Fujita 2002). Turbines could also be geared for
low velocities (25-50 rpm) which would keep the
fish fatalities to a minimum (see Pelc & Fujita 2002).
It has been suggested that larger animals, such as
marine mammals, could be kept away from the
rotors through fences (Pelc & Fujita 2002), but this
may, on the other hand, cause barrier effects in
narrow channels. The use of sonar sensors to shut
the system down when mammals approach the
devices has also been mentioned as an option (Pelc
& Fujita 2002).
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