title: Mobile demersal megafauna at common offshore wind turbine foundations in the German Bight (North Sea) two years after deployment - increased production rate of Cancer pagurus.
abstract: Within the next decades the construction of thousands of different types of large wind turbine foundations in the North Sea will substantially increase the amount of habitat available to reef fauna. To gain first insights which effect these substantial changes in habitat structure and diversity might have on faunal stocks settling on hard substrata, we compared the mobile demersal megafauna associated with the common types of wind turbine foundations ('jacket', 'tripod' and 'monopile with scour protections of natural rock') in the southern German Bight, North Sea. Monopiles with scour protection were mostly colonized by typical reef fauna. They were inhabited by an average of about 5000 edible crabs Cancer pagurus (per foundation), which is more than twice as much as found at the foundation types without scour protection. Strong evidence was found that all three foundation types not only function as aggregation sites, but also as nursery grounds for C. pagurus. Assuming equal shares of the three foundation types in future wind farms, we project that about 27% of the local stock of C. pagurus might be produced on site. When, for example, comparing the existing fauna at 1000 ship wrecks and on the autochthonous soft substrate with those which probably will establish at the foundations of 5000 hypothetically realized wind turbines, it becomes clear that the German Bight in the future will provide new artificial reef habitats for another 320% crabs (C. pagurus) and 50% wrasse (Ctenolabrus rupestris) representing substrata-limited mobile demersal hard bottom species. Further research is urgently required in order to evaluate this overspill as it would be an important ecological effect of the recent offshore wind power development.
authors.affiliation: Krone-Projekte, Unternehmen für Meereskunde, Umweltwissenschaften & Technik, Schleusenstraße 1-3, 27568 Bremerhaven, Germany; Hummerstation Helgoland, Division Biosciences, Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany. Electronic address: r.krone@krone-projekte.de.
authors.forename: R
authors.initials: R
authors.lastname: Krone
authors.affiliation: Bannholzstraße 9, 73579 Schechingen, Germany. Electronic address: Gabrieledederer@gmail.com.
authors.forename: G
authors.initials: G
authors.lastname: Dederer
authors.affiliation: Octopus Science, Büro für Forschungstaucherarbeiten, Övelgönner Straße 25, 20257 Hamburg, Germany. Electronic address: Phil_kanstinger@yahoo.de.
authors.forename: P
authors.initials: P
authors.lastname: Kanstinger
authors.affiliation: Department of Biology and Environmental Sciences, Animal Biodiversity and Evolutionary Biology, Carl von Ossietzky University Oldenburg, Carl von Ossietzky Straße 9-11, 26111 Oldenburg, Germany. Electronic address: philipp.kraemer@uni-oldenburg.de.
authors.forename: P
authors.initials: P
authors.lastname: Krämer
authors.affiliation: Octopod Research & Development GmbH, Kleine Bergstraße 30, 22767 Hamburg, Germany. Electronic address: c.schneider@octopod.de.
authors.forename: C
authors.initials: C
authors.lastname: Schneider
authors.affiliation: Hummerstation Helgoland, Division Biosciences, Alfred Wegener Institute for Polar and Marine Research, Ostkaje 1118, 27498 Helgoland, Germany. Electronic address: Isabel.Schmalenbach@awi.de.
authors.forename: I
authors.initials: I
authors.lastname: Schmalenbach
mesh_terms: D000818:Animals; D044822:Biodiversity; D003386:Brachyura / Q000254:growth & development*; D017753:Ecosystem; D004784:Environmental Monitoring; D009659:North Sea; D011210:Power Plants; D014919:Wind
keywords: Aggregation; Artificial reefs; Habitat creation; Offshore wind farm; Reef effects