摘要：The rapid increase in development of offshore wind energy in European waters
has raised concern for the possible environmental impacts of wind farms. We
studied whether harbour porpoise occurrence has been affected by the presence
of the Dutch offshore wind farm Egmond aan Zee. This was done by studying
acoustic activity of porpoises in the wind farm and in two reference areas using
stationary acoustic monitoring (with T-PODs) prior to construction (baseline: June
2003 to June 2004) and during normal operation of the wind farm (operation:
April 2007 to April 2009). The results show a strong seasonal pattern, with more
activity recorded during winter months. There was also an overall increase in
acoustic activity from baseline to operation, in line with a general increase in
porpoise abundance in Dutch waters over the last decade. The acoustic activity was
significantly higher inside the wind farm than in the reference areas, indicating that the
occurrence of porpoises in this area increased as well. The reasons of this apparent
preference for the wind farm area are not clear. Two possible causes are discussed: an
increased food availability inside the wind farm (reef effect) and/or the absence of
vessels in an otherwise heavily trafficked part of the North Sea (sheltering effect).
