Download Effects of offshore wind turbine foundations on mobile

Effects of offshore wind turbine foundations on
mobile demersal megafauna and pelagic fish research at the alpha ventus offshore wind farm
Roland Krone and Sören Krägefsky
Alfred Wegener Institute
Helmholtz Centre for Polar and Marine Research
StUKplus Conference - Ecological Research at alpha ventus │Berlin
Krone and Krägefsky │ 30.-31.10.2013
Changing German Bight
• Up to 5,000 offshore wind
turbine foundations
• 20% of the German EEZ
Planned
Approved
Under construction
Operating
Depth
EEZ
German exclusive economic zone, German Bight
StUKplus Conference - Ecological Research at alpha ventus │Berlin
Krone and Krägefsky │ 30.-31.10.2013
Impact on mobile demersal megafauna and pelagic fish?
.
Dominated by soft
bottom associated
communities
5,000 new habitats
introduced
New communities,
increase in reef organisms?!
How react pelagic fish?
StUKplus challenges
• Monitoring the effects of construction and operation on pelagic fish
• Quantification of mobile demersal megafauna at the artificial habitats
StUKplus Conference - Ecological Research at alpha ventus │Berlin
Krone and Krägefsky │ 30.-31.10.2013
Effects of construction and operation
on pelagic fish
StUKplus Conference - Ecological Research at alpha ventus │Berlin
Krone and Krägefsky │ 30.-31.10.2013
Questions
•
Do construction and operation redistribute pelagic fish?
•
Do pelagic fish feed on reef organisms inside alpha ventus?
•
Does hydro acoustic generate new findings?
StUKplus Conference - Ecological Research at alpha ventus │Berlin
Krone and Krägefsky │ 30.-31.10.2013
Methods
• Hydro acoustic survey with ship-mounted
multifrequency echosounder 2009 - 2011 (1)
• sampling with net catches (pelagic trawl) (2)
• stomach content analysis of fish caught outside
and within the area of alpha ventus
StUKplus Conference - Ecological Research at alpha ventus │Berlin
Krone and Krägefsky │ 30.-31.10.2013
Results: net catches
 Strong similarity in species composition between net catches
in alpha ventus and at reference sites.
StUKplus Conference - Ecological Research at alpha ventus │Berlin
Krone and Krägefsky │ 30.-31.10.2013
Results: hydro acoustic surveys
 Indication for strong relative decline in abundance of pelagic fish in the
alpha ventus area compared to the surrounding area during construction
phase
Relative abundances inside/outside alpha ventus
day
night
StUKplus Conference - Ecological Research at alpha ventus │Berlin
Krone and Krägefsky │ 30.-31.10.2013
Results: stomach content analysis
 Biofouling organisms from the
foundations are a diminutive
component of the diet of Atlantic
mackerel and Atlantic horse
mackerel
Purple A. mackerels ref
Green A. mackerel within av
Red A. mackerel at FINO1
Blue A. horse mackerel at FINO1
 Atlantic mackerels within the wind
farm had ~ 50% lower fullness
compared to mackerels outside the
wind farm (operation phase)
StUKplus Conference - Ecological Research at alpha ventus │Berlin
Krone and Krägefsky │ 30.-31.10.2013
Mobile demersal megafauna at offshore
wind turbine foundations
StUKplus Conference - Ecological Research at alpha ventus │Berlin
Krone and Krägefsky │ 30.-31.10.2013
Questions
•
How do demersal megafauna communities at foundations
(reef fauna) differ from those on soft bottom?
•
How large are the stocks of mobile demersal megafauna at
alpha ventus foundations?
•
New findings by scientific diving?
StUKplus Conference - Ecological Research at alpha ventus │Berlin
Krone and Krägefsky │ 30.-31.10.2013
Methods
2nd year after construction (2011)
• Sampling in spring and autumn
• Fauna ≥ 1cm (megafauna)
• Towed video camera on sand bottom
6-27 recordings inside av; 7-27 outside
•
Diving belt transects
3-4 tripods and jackets per season
Abundances per foot print
StUKplus Conference - Ecological Research at alpha ventus │Berlin
Krone and Krägefsky │ 30.-31.10.2013
Results: foundation comparison
2nd year after construction
av spring
ref spring
av autumn
ref autumn
Tripod spring
Jacket spring
Tripod autumn
Jacket autumn
 Communities on soft bottom and foundations are not similar
 Community structure at tripods and jackets are similar
 Communities on soft bottom inside and outside are similar
StUKplus Conference - Ecological Research at alpha ventus │Berlin
Krone and Krägefsky │ 30.-31.10.2013
Results: seasonal and differences
Percentage share > 90%
Spring
Soft bottom
Autumn
Spring
Foundations
Autumn
Lars Gutow/AWI
Two years after construction. Seasonal variability or ongoing development?
StUKplus Conference - Ecological Research at alpha ventus │Berlin
Krone and Krägefsky │ 30.-31.10.2013
Result: large stock potential for mobile demersal megafauna
2nd year after construction
Standing stock in alpha ventus ~20,700 Brown crabs (different size)
StUKplus Conference - Ecological Research at alpha ventus │Berlin
Krone and Krägefsky │ 30.-31.10.2013
Result: large stock potential for mobile demersal megafauna
Example: Brown crab colonizing
future wind farms
• 5,000 Tripods = 11.7 Mio. individuals
• Soft bottom + wrecks = 4.2 Mio. individuals
inside EEZ*
 Increased predation pressure
+ 275% Brown crab
 More fishery targets
*Krone et al., 2013
StUKplus Conference - Ecological Research at alpha ventus │Berlin
Krone and Krägefsky │ 30.-31.10.2013
Results: Brown crab nursery and production?
 Large individuals exclusively inhabit the bottom
area!
 Large numbers of small individuals inhabit the
upper sections!
 Upper sections functioning as larvae collectors,
increasing production?!
StUKplus Conference - Ecological Research at alpha ventus │Berlin
Krone and Krägefsky │ 30.-31.10.2013
Summary and outlook
 Construction phase potentially effects pelagic fish!
 The offshore wind power foundations provide habitat for thousands of
mobile demersal reef organisms!
New challenges
• What happens after two years?
• What happens in other German Bight areas?
• Production and redistribution?
Alain Norro/RBINS
• How does reef fauna develop at other foundations
(e. g. with scour protections)?
Literature
Krone R, Gutow L, Dannheim J, Brey T, Schröder A (2013) Mobile demersal megafauna at artificial structures in the German
Bight - likely effects of offshore wind farm development. Estuarine Coastal and Shelf Science 125: 1-9.
Krone R, Schröder A (2011) Wrecks as artificial lobster habitats in the German Bight. Helgoland Marine Research 65: 11-16.
StUKplus Conference - Ecological Research at alpha ventus │Berlin
Krone and Krägefsky │ 30.-31.10.2013
Acknowledgements
We thank Dr. Alexander Schröder, Dr. Lars Gutow, Gabriele Dederer, Philipp Krämer,
Christof Schneider, Philipp Kanstinger and Sebastian Fuhrmann for their contribution to the
project work.
Funding: Federal Ministry for Environment, Nature Conservation and Nuclear Safety,
research project RAVE Ecology (grant no. 0327689A)
Coordination: Federal Maritime and Hydrographic Agency (BSH)
Supervision: Project Management Jülich (PTJ)
Dr. Roland Krone
email [email protected]
152
28549445
StUKplusphone
Conference++49
- Ecological
Research
at alpha ventus │Berlin
Thank you for your attention!
Krone and Krägefsky │ 30.-31.10.2013
Projektlaufzeit 01.07.2008 - 31.07.2012
Projektverlängerung
(Modifikation und Erweiterung
des Beprobungsschema)
Projektbewilligung StUK plus (für 2,5 Jahre der Betriebsphase)
2008
Jul
Errichtungsarbeiten | Betrieb
Forschungstaucherische
Beprobungen
Kampagne
Sept
2009
Okt
Umspannw erk
I
Mai - Jul
Sept
Tripods
Tripods
Jackets
II
Tripods
2011
FINO 1
Mär
2012
Apr
Okt/ Nov
II
IV
V
Sept
VI
VII
Training
2
Training
4
3
3
3
bis Jul
Betriebsphase
Jackets
Umspannwerk
Training
Training
1*
alpha ventus
38
26
7
9
5
34
27
Referenz
23
19
0
9
7
21
26
Wrack
Bodenvideoeinheiten [n]
2010
Apr
1*
Basisdaten,
Ersatzuntersuchungen &
Methodentraining
Bauphase
Bauphase
1. Betrieb sjahr
StUKplus Conference - Ecological Research at alpha ventus │Berlin
Hauptuntersuchung
2. Betrieb sjahr
Krone and Krägefsky │ 30.-31.10.2013
Spring
StUKplus Conference - Ecological Research at alpha ventus │Berlin
Autumn
Krone and Krägefsky │ 30.-31.10.2013