A first estimate of the effect of offshore wind farms on sedimentary organic carbon stocks in the Southern North Sea

Heinatz, Knut; Scheffold, Maike Iris Esther

doi:10.3389/fmars.2022.1068967

Cited by 8 publications

(4 citation statements)

References 23 publications

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“…Though our OWF scenario shows a slight decrease in OC, this is primarily due to the trawling effort redistribution, whereas the wind wake effect shows a similar sign and magnitude as in Daewel et al (2022). Heinatz and Scheffold (2023) estimated a net increase of sediment OC storage at OWFs in the Southern North Sea on the order of 1000 kt throughout a 20 year life cycle, or 50 kt yr -1 . This estimate is an order of magnitude greater than our estimated reduction.…”

Section: Impacts Of Management Scenariosmentioning

confidence: 57%

“…Strong local effects do occur, and the wind wakes and pile turbulence production cause the impacts to extend to considerable distances from the OWFs themselves. A holistic assessment of OWF impacts on sediment OC should consider the OC loss due to seafloor disturbance during construction and decommissioning, as well as secondary effects, such as the colonization of organisms at the foundations of wind turbines, and wind wake impacts on the ecosystem structure (de Borger et al, 2021a;Daewel et al, 2022;Heinatz and Scheffold, 2023). Using an ecosystem model that considers wind wake effects, Daewel et al (2022) simulated local increases in sedimentary carbon of up to 10% after one year, but only a slight net increase of 0.2% for the entire North Sea.…”

Section: Impacts Of Management Scenariosmentioning

confidence: 99%

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Quantification and mitigation of bottom trawling impacts on sedimentary organic carbon stocks in the North Sea

Porz,

Zhang,

Christiansen

et al. 2024

Preprint

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Abstract. The depletion of sedimentary organic carbon stocks by use of bottom-contacting fishing gear and the potential climate impacts resulting from remineralization of the organic carbon to CO2 have recently been heavily debated. In this study, a 3D coupled numerical ocean-sediment-macrobenthos model is used to quantify the impacts of bottom trawling on organic carbon and macrobenthos stocks in North Sea sediments. Using available information on vessel activity, gear components and sediment type, we generate daily time series of trawling impacts and simulate six years of trawling activity in the model, as well as four management scenarios in which trawling effort is redistributed from areas inside to areas outside of trawling closure zones. North Sea sediments contained 552.2±192.4 kt less organic carbon and 13.6±2.6 % less macrobenthos biomass in the trawled simulations than in the untrawled simulations by the end of each year. The organic carbon loss is equivalent to aqueous emission of 2.0±0.7 Mt CO2 each year, half of which is likely to accumulate in the atmosphere on multi-decadal timescales. The impacts were elevated in years with higher levels of trawling pressure and vice versa. Results showed high spatial variability, with a high loss of organic carbon due to trawling in some areas, while organic carbon content increased in nearby untrawled areas following transport and redeposition. The area most strongly impacted was the heavily trawled and carbon-rich Skagerrak. Simulated trawling closures in planned Offshore Wind Farms and Core Fishing Grounds had negligible effects on net sedimentary organic carbon, while closures in Marine Protected Areas had a moderate positive impact. The largest positive impact arose for trawling closures in Carbon Protection Zones, which were defined as areas where organic carbon is most vulnerable to disturbance. In that scenario, the net impacts of trawling on organic carbon and macrobenthos biomass were reduced by 29 % and 54 %, respectively. These results demonstrate that carbon protection and habitat protection can be combined without requiring a reduction in net fishing effort.

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Section: Impacts Of Management Scenariosmentioning

confidence: 57%

Section: Impacts Of Management Scenariosmentioning

confidence: 99%

Quantification and mitigation of bottom trawling impacts on sedimentary organic carbon stocks in the North Sea

Porz,

Zhang,

Christiansen

et al. 2024

Preprint

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“…Only fixed-bottom foundations affect this habitat, completely destroying it where the wind turbines are placed, regardless of the type of foundation technology, though each foundation type has a different 'destruction' footprint. The cable laying, which is needed for both technologies, also dislocates meadows, accounting for 22.86% of the total area disturbed [41].…”

Section: Distribution Of Posidonia Oceanicamentioning

confidence: 99%

Marine Suitability Assessment for Offshore Wind Farms’ Deployment in Thrace, Greece

Gazos,

Vagiona

2024

Sustainability

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The exploitation of renewable energy resources is an effective option to respond to climate change challenges. Wind energy can be exploited more efficiently and effectively than any other renewable energy source. By switching from onshore wind energy projects to offshore, the positive aspects of onshore wind energy remain and, at the same time, no valuable onshore area is occupied, while their efficiency (e.g., capacity factor) is increased. Greece has a rich wind potential and the maritime region of Thrace is one of Greece’s maritime regions with the greatest potential for the development of offshore wind energy. The aim of the present paper is to identify the most appropriate sites for the deployment of offshore wind farms in the region of Thrace. The methodology includes (i) the delineation of the study area and the definition of the support structure of the wind turbine, (ii) the identification of seven (7) exclusion and fifteen (15) assessment criteria, (iii) the suitability analysis under five different zoning scenarios (equal weight, environmental, social, techno-economic, and researchers’ subjective), and (iv) the micro siting and qualitative assessment of the most suitable sites based on energy, environmental, social, and economic criteria. The methodology is based on the combined use of Geographical Information Systems (GISs), specifically ArcGIS Desktop version 10.8.1, wind assessment software tools (WaSPs), specifically WaSP version 12.8, and multi-criteria decision-making methods. The results of the paper illustrate that the optimal suitability area that is proposed for offshore wind farm deployment is located at the easternmost end of the Greek part of the Thracian Sea. The planning and the deployment of offshore wind farm projects should follow a holistic and environmentally driven approach to ensure the integrity of all habitats and species affected.

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“…With the dynamic hydrography, complex seabed topography and high data density, the Skagerrak offers an ideal setting to examine MAR in an environment with various sedimentation patterns. Furthermore, the Skagerrak and North Sea sedimentary systems have been increasingly impacted by anthropogenic activities such as bottom trawling (ICES, 2020), sediment extraction (De Groot, 1986;ICES, 2019;Mielck et al, 2019) or offshore wind park constructions (Heinatz and Scheffold, 2023) since industrial times. Hence, sediment budgeting in this area may improve our understanding of sediment redistribution in a changing environment.…”

Section: Introductionmentioning

confidence: 99%

Modelling mass accumulation rates and 210Pb rain rates in the Skagerrak: lateral sediment transport dominates the sediment input

Spiegel,

Diesing,

Dale

et al. 2024

Front. Mar. Sci.

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Sediment fluxes to the seafloor govern the fate of elements and compounds in the ocean and serve as a prerequisite for research on elemental cycling, benthic processes and sediment management strategies. To quantify these fluxes over seafloor areas, it is necessary to scale up sediment mass accumulation rates (MAR) obtained from multiple sample stations. Conventional methods for spatial upscaling involve averaging of data or spatial interpolation. However, these approaches may not be sufficiently precise to account for spatial variations of MAR, leading to poorly constrained regional sediment budgets. Here, we utilize a machine learning approach to scale up porosity and 210Pb data from 145 and 65 stations, respectively, in the Skagerrak. The models predict the spatial distributions by considering several predictor variables that are assumed to control porosity and 210Pb rain rates. The spatial distribution of MAR is based on the predicted porosity and existing sedimentation rate data. Our findings reveal highest MAR and 210Pb rain rates to occur in two parallel belt structures that align with the general circulation pattern in the Skagerrak. While high 210Pb rain rates occur in intermediate water depths, the belt of high MAR is situated closer to the coastlines due to lower porosities at shallow water depths. Based on the spatial distributions, we calculate a total MAR of 34.7 Mt yr-1 and a 210Pb rain rate of 4.7 · 1014 dpm yr-1. By comparing atmospheric to total 210Pb rain rates, we further estimate that 24% of the 210Pb originates from the local atmospheric input, with the remaining 76% being transported laterally into the Skagerrak. The updated MAR in the Skagerrak is combined with literature data on other major sediment sources and sinks to present a tentative sediment budget for the North Sea, which reveals an imbalance with sediment outputs exceeding the inputs. Substantial uncertainties in the revised Skagerrak MAR and the literature data might close this imbalance. However, we further hypothesize that previous estimates of suspended sediment inputs into the North Sea might have been underestimated, considering recently revised and elevated estimates on coastal erosion rates in the surrounding region of the North Sea.

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A first estimate of the effect of offshore wind farms on sedimentary organic carbon stocks in the Southern North Sea

Cited by 8 publications

References 23 publications

Quantification and mitigation of bottom trawling impacts on sedimentary organic carbon stocks in the North Sea

Quantification and mitigation of bottom trawling impacts on sedimentary organic carbon stocks in the North Sea

Marine Suitability Assessment for Offshore Wind Farms’ Deployment in Thrace, Greece

Modelling mass accumulation rates and 210Pb rain rates in the Skagerrak: lateral sediment transport dominates the sediment input

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