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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