scholarly journals Dynamics and variability of POC burial in depocenters of the North Sea (Skagerrak), Cruise No. AL561, 2.08.2021 – 13.08.2021, Kiel – Kiel, APOC

2021 ◽  
Author(s):  
Mark Schmidt
Keyword(s):  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
North Sea ◽  
Anthropogenic Impacts ◽  
Transport Processes ◽  
High Accumulation ◽  
Gravity Corer ◽  
The North ◽  
The North Sea ◽  
Mineralization Processes

The AL561 cruise was conducted in the framework of the project APOC (“Anthropogenic impacts on Particulate Organic Carbon cycling in the North Sea”). This collaborative project between GEOMAR, AWI, HEREON, UHH, and BUND is to understand how particulate organic carbon (POC) cycling contributes to carbon sequestration in the North Sea and how this ecosystem service is compromised and interlinked with global change and a range of human pressures include fisheries (pelagic fisheries, bottom trawling), resource extraction (sand mining), sediment management (dredging and disposal of dredged sediments) and eutrophication. The main aim of the sampling activity during AL561 cruise was to recover undisturbed sediment from high accumulation sites in the Skagerrak/Kattegat and to subsample sediment/porewater at high resolution in order to investigate sedimentation transport processes, origin of sediment/POC and mineralization processes over the last 100- 200 years. Moreover, the actual processes of sedimentation and POC degradation in the water column and benthic layer will be addressed by sampling with CTD and Lander devices. In total 9 hydroacoustic surveys (59 profiles), 4 Gravity Corer, 7 Multicorer, 3 Lander and 4 CTD stations were successfully conducted during the AL561 cruise. - (Alkor-Berichte ; AL561)

scholarly journals Organic carbon in surface sediments of the North Sea and Skagerrak

2020 ◽  
Author(s):  
Markus Diesing ◽  
Terje Thorsnes ◽  
Lilja Rún Bjarnadóttir
Keyword(s):  
Organic Carbon ◽  
North Sea ◽  
Carbon Stocks ◽  
Carbon Accumulation ◽  
Complex Nature ◽  
Accumulation Rates ◽  
The North ◽  
Continental Shelves ◽  
Shelf Sediments ◽  
The North Sea

Abstract. Continental shelf sediments are places of both rapid organic carbon turnover and accumulation, while at the same time increasingly subjected to human-induced disturbances. Recent research suggests that shelf sediments might have a role to play as a natural climate solution, e.g. by protecting the seafloor against human-induced disturbance. However, we have an incomplete understanding about the centres of organic carbon accumulation and storage on continental shelves. To better constrain the rate of accumulation and the mass of organic carbon that is stored in sediments, we developed and applied a spatial modelling framework that allows to estimate those quantities from sparse observations and predictor variables known or suspected to influence the spatial patterns of these parameters. This paper presents spatial distribution patterns of organic carbon densities and accumulation rates in the North Sea and Skagerrak. We found that organic carbon stocks and accumulation rates are highest in the Norwegian Trough, while large parts of the North Sea are characterised by low stocks and zero net-accumulation. The total stock of organic carbon that is stored in the upper 0.1 m of sediments amounted to 230.5 ± 134.5 Tg, of which approximately 26 % are stored in the Norwegian Trough. Rates of organic carbon accumulation in the Norwegian Trough are on par with those reported from nearby fjords. We provide baseline datasets that could be used in marine management, e.g. for the establishment of carbon protection zones. Additionally, we highlight the complex nature of continental shelves with zones of rapid carbon cycling and accumulation juxtaposed, which will require further detailed and spatially explicit analyses to constrain sedimentary organic carbon stocks and accumulation rates globally.

Change in the North Sea ecosystem from the 1970s to the 2010s: great skua diets reflect changing forage fish, seabirds, and fisheries

2018 ◽  
Vol 76 (4) ◽  
pp. 925-937 ◽  
Author(s):  
Gabriella E Church ◽  
Robert W Furness ◽  
Glen Tyler ◽  
Lucy Gilbert ◽  
Stephen C Votier
Keyword(s):  
North Sea ◽  
Anthropogenic Impacts ◽  
Marine Ecosystem ◽  
Commercial Fishing ◽  
Seabird Species ◽  
Rissa Tridactyla ◽  
Fulmarus Glacialis ◽  
The North ◽  
The North Sea

Abstract Understanding anthropogenic impacts are crucial to maintain marine ecosystem health. The North Sea has changed in recent decades, largely due to commercial fishing and climate change. Seabirds can act as useful indicators of these changes. By analyzing n = 20 013 pellets and n = 24 993 otoliths regurgitated by great skuas Stercorarius skua in northern Scotland over five decades from the 1970s to the 2010s (in 36 years 1973–2017), we reveal how the diet of this top predator has changed alongside the changing North Sea ecosystem. Sandeels Ammodytes spp. were the most common dietary item during the 1970s, but became virtually absent from the 1980s onward. Discarded whitefish dominated skua diets from the 1980s to the present day, despite long-term declines in North Sea discard production. However, the discarded fish eaten by great skuas has become smaller and the species composition changed. Skua pellets only rarely contained avian prey in the 1970s but this increased during the 1980s, and fluctuated between 10% and 20% from the 1990s to 2010s. There have also been changes in the avian prey in the diet—black-legged kittiwakes Rissa tridactyla generally being replaced by auks Alcid spp. and northern fulmars Fulmarus glacialis. The Shetland marine ecosystem has experienced steep declines in sandeel stocks and in seabirds that feed on them. Great skuas have been able to prey switch to respond to this change, supported by abundant discards, enabling them to maintain a favourable population status while other seabird species have declined.

scholarly journals Organic carbon densities and accumulation rates in surface sediments of the North Sea and Skagerrak

2021 ◽  
Vol 18 (6) ◽  
pp. 2139-2160
Author(s):  
Markus Diesing ◽  
Terje Thorsnes ◽  
Lilja Rún Bjarnadóttir
Keyword(s):  
Organic Carbon ◽  
North Sea ◽  
Carbon Stocks ◽  
Carbon Accumulation ◽  
Anthropogenic Activity ◽  
Accumulation Rates ◽  
The North ◽  
Continental Shelves ◽  
Shelf Sediments ◽  
The North Sea

Abstract. Continental shelf sediments are places of both rapid organic carbon turnover and accumulation, while at the same time increasingly subjected to human-induced disturbances. Recent research suggests that shelf sediments might have a role to play as a natural climate solution, e.g. by storing organic carbon if left undisturbed from anthropogenic activity. However, we have an incomplete understanding about the centres of organic carbon accumulation and storage on continental shelves. To better constrain the rate of accumulation and the mass of organic carbon that is stored in sediments, we developed and applied a spatial modelling framework that allows us to estimate those quantities from sparse observations and predictor variables known or suspected to influence the spatial patterns of these parameters. This paper presents spatial distribution patterns of organic carbon densities and accumulation rates in the North Sea and Skagerrak. We found that organic carbon stocks and accumulation rates are highest in the Norwegian Trough, while large parts of the North Sea are characterised by low stocks and zero net accumulation. The total stock of organic carbon that is stored in the upper 0.1 m of sediments amounted to 230.5 ± 134.5 Tg C, of which approximately 26 % is stored in the Norwegian Trough. Rates of organic carbon accumulation in the Norwegian Trough are comparable with those reported from nearby fjords. We provide baseline datasets that could be used in marine management, e.g. for the establishment of “carbon protection zones”. Additionally, we highlight the complex nature of continental shelves with zones of rapid carbon cycling and accumulation juxtaposed, which will require further detailed and spatially explicit analyses to constrain sedimentary organic carbon stocks and accumulation rates globally.

scholarly journals Offshore Windfarm Footprint of Sediment Organic Matter Mineralization Processes

2021 ◽  
Vol 8 ◽  
Author(s):  
Emil De Borger ◽  
Evgeny Ivanov ◽  
Arthur Capet ◽  
Ulrike Braeckman ◽  
Jan Vanaverbeke ◽  
...  
Keyword(s):  
Organic Matter ◽  
North Sea ◽  
Energy Transition ◽  
Deposition Fluxes ◽  
Southern Bight ◽  
Marine Life ◽  
The North ◽  
The North Sea ◽  
Mineralization Processes ◽  
Sediment Layers

Offshore windfarms (OWFs) offer part of the solution for the energy transition which is urgently needed to mitigate effects of climate change. Marine life has rapidly exploited the new habitat offered by windfarm structures, resulting in increased opportunities for filter- and suspension feeding organisms. In this study, we investigated the effects of organic matter (OM) deposition in the form of fecal pellets expelled by filtering epifauna in OWFs, on mineralization processes in the sediment. OM deposition fluxes produced in a 3D hydrodynamic model of the Southern Bight of the North Sea were used as input in a model of early diagenesis. Two scenarios of OWF development in the Belgian Part of the North Sea (BPNS) and its surrounding waters were calculated and compared to a no-OWF baseline simulation. The first including constructed OWFs as of 2021, the second containing additional planned OWFs by 2026. Our results show increased total mineralization rates within OWFs (27–30%) in correspondence with increased deposition of reactive organic carbon (OC) encapsulated in the OM. This leads to a buildup of OC in the upper sediment layers (increase by ∼10%) and an increase of anoxic mineralization processes. Similarly, denitrification rates within the OWFs increased, depending on the scenario, by 2–3%. Effects were not limited to the OWF itself: clear changes were noticed in sediments outside of the OWFs, which were mostly opposite to the “within-OWF” effects. This contrast generated relatively small changes when averaging values over the full modeling domain, however, certain changes, such as for example the increased storage of OC in sediments, may be of significant value for national / regional carbon management inventories. Our results add to expectations of ecosystem-wide effects of windfarms in the marine environments, which need to be researched further given the rapid rate of expansion of OWFs.

The benthic environment of the North Sea (56° to 61°N)

1988 ◽  
Vol 68 (1) ◽  
pp. 125-141 ◽  
Author(s):  
D. Basford ◽  
A. Eleftheriou
Keyword(s):  
Trace Metals ◽  
Organic Carbon ◽  
North Sea ◽  
Large Scale ◽  
Clay Content ◽  
The North ◽  
Benthic Environment ◽  
The North Sea ◽  
Sedimentation Basins ◽  
Physical And Chemical

In an attempt to describe the physical and chemical characteristics of the sediments as an environment for the invertebrate benthos, a total of 273 stations covering the sector from 56° N to 61° N in the North Sea was sampled. The sediment samples which were collected by grab and corer were analysed for particle size (as well as silt-clay content and sorting), organic carbon, plant pigments and trace metals (Cd, Pb, Zn, Ni, Co, Cu). On a smaller scale a few stations were sampled for redox potential, pH and pesticides.Taking into account the geological history and the on-going hydrographic processes, explanations for the formation of the sedimentary provinces in the North Sea were provided. The sediments were predominantly fine to medium sand, but there was a depth-related gradient with the finer grades, organic carbon and, to a lesser extent, plant pigment being found in the deeper sedimentation basins of the Fladen Grounds and Norwegian Trench.Trace metals and pesticide contaminants associated with the finer organic and inorganic fractions were higher in the sediments of the above deeper areas as well as in the vicinity of estuaries. It could be concluded that despite the enhanced concentrations of Cd, Ni, Pb and Co, at the east of Shetland, which were due to a geochemical anomaly, there was no evidence of any important or large-scale contamination of the North Sea as a whole.

scholarly journals Trends in inorganic and organic carbon in a bloom of Emiliania huxleyi in the North Sea

1996 ◽  
Vol 143 ◽  
pp. 271-282 ◽  
Author(s):  
E Buitenhuis ◽  
J van Bleijswijk ◽  
D Bakker ◽  
M Veldhuis
Keyword(s):  
Organic Carbon ◽  
North Sea ◽  
Emiliania Huxleyi ◽  
The North ◽  
The North Sea ◽  
Inorganic And Organic

Life history strategy and impacts of environmental variability on early life stages of two marine fishes in the North Sea: an individual-based modelling approach

2011 ◽  
Vol 68 (3) ◽  
pp. 426-443 ◽  
Author(s):  
Ute Daewel ◽  
Myron A. Peck ◽  
Corinna Schrum
Keyword(s):  
North Sea ◽  
Early Life ◽  
Environmental Variability ◽  
Larval Fish ◽  
Transport Processes ◽  
Life Stages ◽  
Early Life Stages ◽  
The North ◽  
The North Sea ◽  
Fish Survival

We employed a suite of coupled models to estimate the influence of environmental variability in the North Sea on early life stages of sprat ( Sprattus sprattus ), a small pelagic clupeid, and Atlantic cod ( Gadus morhua ), a demersal gadoid. Environmentally driven changes in bottom-up processes were projected to impact the survival and growth of eggs and larvae of these marine fish species in markedly different ways. We utilized a spatially explicit, individual-based model (IBM) to estimate larval fish survival and a 3D ecosystem model (ECOSMO) to provide variable prey fields. The model was applied to each of 3 years (1990, 1992, 1996) specifically characterized by interannual differences in water temperature in late winter and spring. Our results indicated that an important mechanism connecting environmental factors to larval fish survival was the match–mismatch dynamics of first-feeding larvae and their prey, which was species-specific because of (i) differences in the timing and locations of spawning, (ii) the duration of endogenously feeding life stages, and (iii) prey thresholds required for larval survival. Differences in transport processes also played an important role for the potential survival of larvae of both species.

Sign in / Sign up

Export Citation Format

Share Document