Looking beyond stratification:  a model-based analysis of  the  biological drivers of oxygen  deficiency in the North Sea

Große, Fabian; Greenwood, Naomi; Kreus, Markus; Lenhart, Hermann; Machoczek, Detlev; Pätsch, Johannes; Salt, Lesley; Thomas, Helmuth

doi:10.5194/bg-13-2511-2016

Cited by 42 publications

(83 citation statements)

References 64 publications

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“…Other studies (OSPAR, 2010;Painting et al, 2013) showed that N inputs from the large Dutch and German rivers are the major contributors to TN in the coastal southern and southeastern North Sea, respectively, while those from the rivers at the British North Sea coast extend far east into the off-shore southern North Sea. This, together with the findings by Große et al (2016), suggests that these N sources have a strong influence on the O 2 dynamics in the southern and southeastern North Sea.…”

Section: Introductionsupporting

confidence: 65%

“…Große et al (2016) showed that the model system captures the main features of observed O 2 concentrations in the North Sea. Therefore, only the simulated volume transports are validated and spatial distributions of TN from selected sources are presented and compared to earlier TBNT studies.…”

Section: Introductionmentioning

confidence: 94%

“…We use a three-dimensional (3D) model consisting of the physical model HAMSOM (HAMburg Shelf Ocean Model; Backhaus, 1985;Pohlmann, 1991Pohlmann, , 1996 and the biogeochemical model ECOHAM (ECOsystem model, HAMburg; Pätsch and Kühn, 2008;Kühn et al, 2010;Lorkowski et al, 2012;Große et al, 2016). HAMSOM is a baroclinic, primitive equation model using the hydrostatic and Boussinesq approximations (Pohlmann, 1991).…”

Section: The Hamsom-ecoham Modelmentioning

confidence: 99%

“…ECOHAM simulates the cycles of carbon (C), N, P, silicon (Si) and O 2 (Pätsch and Kühn, 2008;Lorkowski et al, 2012). The present version of ECOHAM is identical to that used by Große et al (2016). Lorkowski et al (2012) provide a full description of the ECOHAM model equations and parameter settings.…”

Section: The Hamsom-ecoham Modelmentioning

confidence: 99%

“…Thus, O 2 deficiency remains a persistent problem in the North Sea and the investigation of its causes is essential for the ecological management. Große et al (2016) applied a physical-biogeochemical model to the North Sea analyzing the physico-biochemical interactions that make the southeastern North Sea most susceptible to O 2 deficiency. They found that the occurrence of distinct seasonal thermal stratification, resulting in a thin sub-thermocline layer in this region of intermediate depth, and high local near-surface net primary production (NPP) constitute the key factors.…”

Section: Introductionmentioning

confidence: 99%

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A Novel Modeling Approach to Quantify the Influence of Nitrogen Inputs on the Oxygen Dynamics of the North Sea

et al. 2017

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Oxygen (O 2 ) deficiency, i.e., dissolved O 2 concentrations below 6 mg O 2 L −1 , is a common feature in the southern North Sea. Its evolution is governed mainly by the presence of seasonal stratification and production of organic matter, which is subsequently degraded under O 2 consumption. The latter is strongly influenced by riverine nutrient loads, i.e., nitrogen (N) and phosphorus (P). As riverine P loads have been reduced significantly over the past decades, this study aims for the quantification of the influence of riverine and non-riverine N inputs on the O 2 dynamics in the southern North Sea. For this purpose, we present an approach to expand a nutrient-tagging technique for physical-biogeochemical models -often referred to as 'trans-boundary nutrient transports' (TBNT) -by introducing a direct link to the O 2 dynamics. We apply the expanded TBNT to the physical-biogeochemical model system HAMSOM-ECOHAM and focus our analysis on N-related O 2 consumption in the southern North Sea during 2000-2014. The analysis reveals that near-bottom O 2 consumption in the southern North Sea is strongly influenced by the N supply from the North Atlantic across the northern shelf edge. However, riverine N sources -especially the Dutch, German and British rivers -as well as the atmosphere also play an important role. In the region with lowest simulated O 2 concentrations (around 56 • N, 6.5 • E), riverine N on average contributes 39% to overall near-bottom O 2 consumption during seasonal stratification. Here, the German and the large Dutch rivers constitute the highest riverine contributions (11% and 10%, respectively). At a site in the Oyster Grounds (around 54.5 • N, 4 • E), the average riverine contribution adds up to 41%, even exceeding that of the North Atlantic. Here, highest riverine contributions can be attributed to the Dutch and British rivers adding up to almost 28% on average. The atmospheric contribution results in 13%. Our results emphasize the importance of anthropogenic N inputs and seasonal stratification for the O 2 conditions in the southern North Sea. They further suggest that reductions in the riverine and atmospheric N inputs may have a relevant positive effect on the O 2 levels in this region.

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Section: Introductionsupporting

confidence: 65%

Section: Introductionmentioning

confidence: 94%

Section: The Hamsom-ecoham Modelmentioning

confidence: 99%

Section: The Hamsom-ecoham Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Novel Modeling Approach to Quantify the Influence of Nitrogen Inputs on the Oxygen Dynamics of the North Sea

et al. 2017

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Bottom mixed layer oxygen dynamics in the Celtic Sea

et al. 2020

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The seasonally stratified continental shelf seas are highly productive, economically important environments which are under considerable pressure from human activity. Global dissolved oxygen concentrations have shown rapid reductions in response to anthropogenic forcing since at least the middle of the twentieth century. Oxygen consumption is at the same time linked to the cycling of atmospheric carbon, with oxygen being a proxy for carbon remineralisation and the release of CO2. In the seasonally stratified seas the bottom mixed layer (BML) is partially isolated from the atmosphere and is thus controlled by interplay between oxygen consumption processes, vertical and horizontal advection. Oxygen consumption rates can be both spatially and temporally dynamic, but these dynamics are often missed with incubation based techniques. Here we adopt a Bayesian approach to determining total BML oxygen consumption rates from a high resolution oxygen time-series. This incorporates both our knowledge and our uncertainty of the various processes which control the oxygen inventory. Total BML rates integrate both processes in the water column and at the sediment interface. These observations span the stratified period of the Celtic Sea and across both sandy and muddy sediment types. We show how horizontal advection, tidal forcing and vertical mixing together control the bottom mixed layer oxygen concentrations at various times over the stratified period. Our muddy-sand site shows cyclic spring-neap mediated changes in oxygen consumption driven by the frequent resuspension or ventilation of the seabed. We see evidence for prolonged periods of increased vertical mixing which provide the ventilation necessary to support the high rates of consumption observed.

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The large-scale impact of offshore wind farm structures on pelagic primary productivity in the southern North Sea

et al. 2018

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This research is funded by the Marine, Coastal and Polar Systems (PACES II) of the Hermann von Helmholtz-Gemeinschaft Deutscher Forschungszentren e.V.. K.S. is funded by the European Commission Erasmus Mundus Masters Course in Environmental Sciences, Policy and Management (MESPOM). C.L., O.K. and K.K. received support from the "Modular System for Shelves and Coasts" (MOSSCO) grant provided by the Bundesministerium für Bildung und Forschung under agreements 03F0667A and 03F0667B; O.K. and K.W. are also supported by the DFG priority programme 1704 "Flexibility matters: Interplay between trait diversity and ecological dynamics using aquatic communities as model system" (DynaTrait) under grant agreement KE 1970/1-1. K.K. is furthermore supported by the DFG Collaborative Research Center "Energy Transfers in Atmosphere and Ocean" TRR181. We thank all co-developers of the model coupling framework MOSSCO, foremost M. Hassan Nasermoaddeli and Richard Hofmeister. The authors gratefully acknowledge the computing time granted by the John von Neumann Institute for Computing (NIC) and provided on the supercomputer JURECA at Forschungszentrum Jülich. We are grateful to the open source community that provided many of the tools used in this study, including but not limited to the communities developing ESMF, FABM, GETM and GOTM.

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Looking beyond stratification: a model-based analysis of the biological drivers of oxygen deficiency in the North Sea

Cited by 42 publications

References 64 publications

A Novel Modeling Approach to Quantify the Influence of Nitrogen Inputs on the Oxygen Dynamics of the North Sea

A Novel Modeling Approach to Quantify the Influence of Nitrogen Inputs on the Oxygen Dynamics of the North Sea

Bottom mixed layer oxygen dynamics in the Celtic Sea

The large-scale impact of offshore wind farm structures on pelagic primary productivity in the southern North Sea

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