Ecological implications of removing a concrete gas platform in the North Sea

Sampling hard substrates in Dutch offshore wind farms : work plan towards an offshore wind farm hard substrate sampling & monitoring programme in the Netherlands [MONS-project ID46]

“…The most applied method has been diving, often carried out by commercial surface supplied or scientific scuba divers collecting samples using putty knives, scraping the fauna from the structure and collecting it in nets. This has been applied in the Netherlands (Bouma and Lengkeek, 2012;Vanagt and Faasse, 2014), Belgium (De Mesel et al, 2015), Germany (Krone et al, 2013b), the UK (Bessell, 2008) and Denmark (Leonhard and Frederiksen, 2006) and on offshore oil and gas platforms in Dutch waters (Coolen et al, 2020c(Coolen et al, , 2020a as well as on rocky reefs and shipwrecks (Coolen et al, 2016(Coolen et al, , 2015aLengkeek et al, 2013b).…”

“…Since novel methods may be needed to improve safety and cost efficiency of sample acquisition, a set of methods with which there is no or very limited prior experience in OWFs in the Netherlands as well as methods that are under development, have been included as well. Bouma and Lengkeek, 2013;De Mesel et al, 2015;Krone et al, 2013b;Mavraki et al, 2021;Vanagt and Faasse, 2014 Oil and gas platforms Coolen et al, 2020cCoolen et al, , 2020aCoolen et al, , 2020bLuttikhuizen et al, 2019;Schutter et al, 2019;van der Stap et al, 2016Shipwrecks Coolen et al, 2016Krone and Schröder, 2011;Lengkeek et al, 2013bLengkeek et al, , 2013aSchrieken et al, 2013 Geogenic reefs Coolen et al, 2015a;Lengkeek et al, 2017;Schrieken et al, 2013 The MONS OWF scrape monitoring programme aims to collect quantitative data on the complete epifauna community, including small species, and provide weights and counts of all species. Video monitoring will not be able to provide the needed data, since significant taxonomic detail is often lacking and many species are not visible on video (van der Stap et al, 2016).…”

“…-An inventory of the epifauna community on the Halfweg concrete gravity based foundation in the Netherlands after removal of the gas platform that was present on top of this foundation (Coolen et al, 2020a). Inventories around biogenic reefs, such as the mixed shellfish reef in the Voordelta (Christianen et al, 2018;Sas et al, 2018Sas et al, , 2016.…”

“…This was included as a first priority in the development steps. The ideal final version of this ROV marine growth sample tool was envisioned to be able to do the following: − Take samples from depths up to 200 meters (to also allow sampling outside Dutch waters); − Take samples of a known surface area (with <10% variation in size) o Example area: 0.05 m 2 , as used for the WMR sample campaigns (Coolen et al, 2020c(Coolen et al, , 2020a or 0.056 m 2 as used for the Dutch wind farm sampling campaigns so far (Bouma and Lengkeek, 2013;Vanagt and Faasse, 2014).…”

“…These and other studies from neighbouring countries (De Mesel et al, 2015;Kerckhof et al, 2019;Krone et al, 2013b;Leonhard and Frederiksen, 2006) or on similar installations [i.e. oil and gas platforms (Coolen et al, 2020c(Coolen et al, , 2020a shared database (Coolen et al, 2021) but this lacks data on communities >12 years after construction since wind farms of this age have not yet been monitored.…”