Mobile demersal megafauna at artificial structures in the German Bight – Likely effects of offshore wind farm development

Abstract

This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. Within the next few decades, large underwater structures of thousands of wind turbines in the northern European shelf seas will substantially increase the amount of habitat available for mobile demersal megafauna. As a first indication of the possible effects of this large scale habitat creation on faunal stocks settling on hard substrata, we compared selected taxa of the mobile demersal megafauna (decapods and fish) associated with the foundation of an offshore research platform (a wind-power foundation equivalent) with those of five shipwrecks and different areas of soft bottoms in the southern German Bight, North Sea. When comparing the amount of approximately 5000 planned wind-power foundations (covering 5.1 Â 10 6 m 2 of bottom area) with the existing number of at least 1000 shipwrecks (covering 1.2 Â 10 6 m 2 of bottom area), it becomes clear that the southern North Sea will provide about 4.3 times more available artificial hard substratum habitats than currently available. With regard to the fauna found on shipwrecks, on soft substrata and on the investigated wind-power foundation, we predict that the amount of added hard substrata will allow the stocks of substrata-limited mobile demersal hard bottom species to increase by 25e165% in that area. The fauna found at the offshore platform foundations is very similar to that at shipwrecks. Megafauna abundances at the foundations, however, are lower compared to those at the highly fractured wrecks and are irregularly scattered over the foundations. The upper regions of the platform construction (5 and 15 m depth) were only sparsely colonized by mobile fauna, the anchorages, however, more densely. The faunal assemblages from the shipwrecks and the foundations, respectively, as well as from the soft bottoms clearly differed from each other. We predict that new wind-power foundations will support the spread of hard bottom fauna into soft bottom areas with low wreck densities.

Ecology of the brown crab (Cancer pagurus) : and production potential for passive fisheries in Dutch offshore wind farms

“…Structurally complex habitats provide refuge against predation for decapods in their final larval stage (megalopae) and early juveniles. Artificial hard substrate such as wind turbines, shipwrecks and oil platforms are known to provide habitat and attract recruitment of crustaceans (Coolen et al, 2018, Krone et al, 2013, Page et al, 1999. The finding of high amounts of small individuals (CW: 10-60 mm) at wind turbines indicated that the upper construction parts of the WTF may also act as a nursery ground, and thus as an artificial larvae collector for C. pagurus (Krone et al, 2017, Krone et al, 2013.…”

“…Artificial hard substrate such as wind turbines, shipwrecks and oil platforms are known to provide habitat and attract recruitment of crustaceans (Coolen et al, 2018, Krone et al, 2013, Page et al, 1999. The finding of high amounts of small individuals (CW: 10-60 mm) at wind turbines indicated that the upper construction parts of the WTF may also act as a nursery ground, and thus as an artificial larvae collector for C. pagurus (Krone et al, 2017, Krone et al, 2013. Besides structural complexity megalopae in general actively select a habitat suitable for settlement by detecting abiotic and biotic environmental stimuli such as changes in temperature and salinity, and chemical cues derived from conspecific adults and/or nursery areas (Forward et al, 2001).…”

Offshore wind park monitoring programmes, lessons learned and recommendations for the future

“…Belgian OWP monitoring programme, Reubens et al, 2014a, b) or jacket foundations (e.g. German OWP monitoring programme, Krone et al, 2013a). Preliminary comparisons already demonstrated a difference in ecology between the different foundation types (Krone, 2014).…”

“…cod and pouting (Reubens et al, 2014b), but several invertebrate (e.g. edible crab Cancer pagurus and European lobster Homarus gammarus) and fish species common to OWPs, were so far less investigated (Krone, 2012;Krone et al, 2013a). Investigations of their habitat use for example would shed light on the key habitat features that are essential to maintain a sustained local population of these species.…”

Setting an agenda for biofouling research for the marine renewable energy industry

“…On the other hand, artificial reef effects can result in negative ecological impacts since their associated community composition may not be the same as natural reef communities in the same geographical area, which could lead to ecosystem changes as noted in research on the foundations of the Alphaventus offshore windfarm [67,68]. Artificial reef effects may vary depending on the existing ecosystem, geographical location and specific environmental features [69].…”