Offshore Wind Power Projects in the Great Lakes - Ministry of ...

Offshore wind power projects in the Great Lakes: Background and science considerations for fish and fish habitat
type study would be favourable as it represents the most statistically robust design (Wind
Turbine Guidelines Advisory Committee 2010). However, in instances where the severity of the
impact is expected to decrease with increasing distance from the source, or where the potential
spatial extent of the effect is uncertain, gradient sampling design often proves more powerful
than a BACI design in detecting changes due to anthropogenic disturbances (Ellis & Schneider
1996). In addition, a gradient sampling design has the added advantage of not requiring an
arbitrary selection of control or reference sites. As discussed earlier, establishing a control or
reference site can be challenging in the field, especially for far-ranging effects which necessitate
that the impact and reference areas be located at significant distances from one another where
physical and ecological similarities decrease. Finally, the results of a gradient design model are
often easier to interpret (Ellis & Schneider 1996), which might make them more useful to
proponents or members of the general public interested in reviewing the outcome of wind power
project monitoring programmes. Examples of how these experimental designs have been used to
detect the impacts of specific wind power project activities or components are reviewed below.
5.4 Monitoring the effects of noise
To evaluate the impact of noise on fish, whether from loud construction activities like pile
driving or from operating wind turbines, various types of baseline information will be required.
Essential to any study of anthropogenic noise disturbance to fish or other aquatic organisms are
measurements of background or ambient noise within the project area and the anticipated area of
impact. Underwater sound levels would be recorded prior to the initiation of construction
activities, and measured under various seasonal conditions in order to fully characterize the
ambient soundscape of the area. These background noise levels will serve as a comparison from
which to gauge the relative contribution or significance of novel sound sources to the local
acoustic environment.
In addition, it is important to thoroughly characterize the sounds generated during the specific
activity of interest (e.g. pile-driving) or produced by operating wind turbines, depending on
which phase is being investigated. This will include accurately measuring the acoustic signature
of the sound source and the sound pressure levels across the full range of frequencies using
appropriate sound measuring devices or equipment. Information on source sound pressure levels,
as well as site specific data on water depth and substrate type are necessary to be able to
Aquatic Research and Development Section 62