The first offshore wind farm ‘alpha ventus’ in the German North Sea was constructed north east of Borkum Reef Ground approximately 45 km north off the German coast in 2008 and 2009 using percussive piling for the foundations of 12 wind turbines. Visual monitoring of harbour porpoises was conducted prior to as well as during construction and operation by means of 15 aerial line transect distance sampling surveys, from 2008 to 2010. Static acoustic monitoring (SAM) with echolocation click loggers at 12 positions was performed additionally from 2008 to 2011. SAM devices were deployed between 1 and 50 km from the centre of the wind farm. During aerial surveys, 18 600 km of transect lines were covered in two survey areas (10 934 and 11 824 km2) and 1392 harbour porpoise sightings were recorded. Lowest densities were documented during the construction period in 2009. The spatial distribution pattern recorded on two aerial surveys three weeks before and exactly during pile-driving points towards a strong avoidance response within 20 km distance of the noise source. Generalized additive modelling of SAM data showed a negative impact of pile-driving on relative porpoise detection rates at eight positions at distances less than 10.8 km. Increased detection rates were found at two positions at 25 and 50 km distance suggesting that porpoises were displaced towards these positions. A pile-driving related behavioural reaction could thus be detected using SAM at a much larger distance than a pure avoidance radius would suggest. The first waiting time (interval between porpoise detections of at least 10 min), after piling started, increased with longer piling durations. A gradient in avoidance, a gradual fading of the avoidance reaction with increasing distance from the piling site, is hence most probably a product of an incomplete displacement during shorter piling events.
Effects of pile-driving on harbour porpoises (Phocoena phocoena) at the first offshore wind farm in Germany
Michael Dähne,A. Gilles,K. Lucke,Verena Peschko,S. Adler,Kathrin Krügel,Janne K Sundermeyer,U. Siebert
Published 2013 in Environmental Research Letters
ABSTRACT
PUBLICATION RECORD
- Publication year
2013
- Venue
Environmental Research Letters
- Publication date
2013-04-04
- Fields of study
Physics, Economics, Environmental Science
- Identifiers
- External record
- Source metadata
Semantic Scholar
CITATION MAP
EXTRACTION MAP
CLAIMS
- Static acoustic monitoring showed reduced porpoise detection rates at eight positions closer than 10.8 km, with higher detection rates at 25 km and 50 km suggesting displacement toward those locations.박진우 (dztg5apj7m) extractionB (s683577b42) reviewKiller Whale (322360f1c1) reviewq (76h6bfydm6) review
CONCEPTS
- aerial line transect distance sampling surveys
Visual aircraft surveys flown along transects to estimate porpoise distribution and density.
Aliases: aerial surveys, line transect distance sampling
박진우 (dztg5apj7m) extractionB (s683577b42) reviewKiller Whale (322360f1c1) reviewq (76h6bfydm6) review - alpha ventus offshore wind farm
The first offshore wind farm in the German North Sea, used as the study site for the monitoring campaign.
Aliases: alpha ventus
박진우 (dztg5apj7m) extractionB (s683577b42) reviewKiller Whale (322360f1c1) reviewq (76h6bfydm6) review - echolocation click loggers
Acoustic devices deployed at fixed positions to record harbour porpoise echolocation clicks.
Aliases: click loggers
박진우 (dztg5apj7m) extractionB (s683577b42) reviewKiller Whale (322360f1c1) reviewq (76h6bfydm6) review - first waiting time
The interval after piling begins until the next porpoise detection gap of at least 10 minutes ends.
Aliases: waiting time
박진우 (dztg5apj7m) extractionB (s683577b42) reviewKiller Whale (322360f1c1) reviewq (76h6bfydm6) review - harbour porpoise
A small marine cetacean species monitored acoustically and visually around the wind farm.
Aliases: harbor porpoise, Phocoena phocoena
박진우 (dztg5apj7m) extractionB (s683577b42) reviewKiller Whale (322360f1c1) reviewq (76h6bfydm6) review - percussive piling
A foundation installation method that drives turbine foundations into the seabed by repeated hammer blows.
Aliases: piling
박진우 (dztg5apj7m) extractionB (s683577b42) reviewKiller Whale (322360f1c1) reviewq (76h6bfydm6) review - pile-driving
The noisy construction activity of driving offshore wind turbine foundations into place.
Aliases: driving
박진우 (dztg5apj7m) extractionB (s683577b42) reviewKiller Whale (322360f1c1) reviewq (76h6bfydm6) review - relative porpoise detection rates
A measure of porpoise click detections at monitoring positions relative to the sampling effort or baseline.
Aliases: detection rates
박진우 (dztg5apj7m) extractionB (s683577b42) reviewKiller Whale (322360f1c1) reviewq (76h6bfydm6) review - static acoustic monitoring
Fixed-position acoustic monitoring of porpoise echolocation clicks using deployed loggers.
Aliases: SAM
박진우 (dztg5apj7m) extractionB (s683577b42) reviewKiller Whale (322360f1c1) reviewq (76h6bfydm6) review
REFERENCES
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