Diurnal pattern, seasonal change and variability of oxygen in the water column of the oyster ground (North sea) in spring-summer 1981

1984 ◽  
Vol 18 (1-2) ◽  
pp. 13-30 ◽  
Author(s):  
S.B. Tijssen ◽  
F.J. Wetsteyn
Keyword(s):  
Water Column ◽  
Seasonal Change ◽  
North Sea ◽  
Diurnal Pattern ◽  
Oyster Ground

scholarly journals Evaluation of numerical models by FerryBox and fixed platform in situ data in the southern North Sea

Ocean Science ◽  
2015 ◽  
Vol 11 (6) ◽  
pp. 879-896 ◽  
Author(s):  
M. Haller ◽  
F. Janssen ◽  
J. Siddorn ◽  
W. Petersen ◽  
S. Dick
Keyword(s):  
North Sea ◽  
High Frequency ◽  
Numerical Models ◽  
Spatial Scales ◽  
Model Performance ◽  
Eastern Coast ◽  
Southern North Sea ◽  
In Situ Data ◽  
Oyster Ground ◽  
Study Results

Abstract. For understanding and forecasting of hydrodynamics in coastal regions, numerical models have served as an important tool for many years. In order to assess the model performance, we compared simulations to observational data of water temperature and salinity. Observations were available from FerryBox transects in the southern North Sea and, additionally, from a fixed platform of the MARNET network. More detailed analyses have been made at three different stations, located off the English eastern coast, at the Oyster Ground and in the German Bight. FerryBoxes installed on ships of opportunity (SoO) provide high-frequency surface measurements along selected tracks on a regular basis. The results of two operational hydrodynamic models have been evaluated for two different time periods: BSHcmod v4 (January 2009 to April 2012) and FOAM AMM7 NEMO (April 2011 to April 2012). While they adequately simulate temperature, both models underestimate salinity, especially near the coast in the southern North Sea. Statistical errors differ between the two models and between the measured parameters. The root mean square error (RMSE) of water temperatures amounts to 0.72 °C (BSHcmod v4) and 0.44 °C (AMM7), while for salinity the performance of BSHcmod is slightly better (0.68 compared to 1.1). The study results reveal weaknesses in both models, in terms of variability, absolute levels and limited spatial resolution. Simulation of the transition zone between the coasts and the open sea is still a demanding task for operational modelling. Thus, FerryBox data, combined with other observations with differing temporal and spatial scales, can serve as an invaluable tool not only for model evaluation, but also for model optimization by assimilation of such high-frequency observations.

scholarly journals Linked sediment and water-column methanotrophy at a man-made gas blowout in the North Sea: Implications for methane budgeting in seasonally stratified shallow seas

2016 ◽  
Vol 61 (S1) ◽  
pp. S367-S386 ◽  
Author(s):  
Lea Steinle ◽  
Mark Schmidt ◽  
Lee Bryant ◽  
Matthias Haeckel ◽  
Peter Linke ◽  
...  
Keyword(s):  
Water Column ◽  
North Sea ◽  
The North ◽  
The North Sea ◽  
Shallow Seas

Metabolic alkalinity release from the Elbe estuary to the North Sea

2021 ◽  
Author(s):  
Mona Norbisrath ◽  
Jeannette Hansen ◽  
Kirstin Dähnke ◽  
Tina Sanders ◽  
Justus E. E. van Beusekom ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Water Column ◽  
Fresh Water ◽  
North Sea ◽  
Total Alkalinity ◽  
Elbe Estuary ◽  
Metabolic Processes ◽  
The North ◽  
Carbon Species ◽  
The North Sea

<p>The Elbe is the largest river entering the German Bight. Its estuary is a heavily used waterway connecting the sea to Germany’s biggest port in Hamburg. The Elbe navigation channel is continuously dredged, and agricultural fertilizer input from the catchment ensuing large phytoplankton blooms in the river Elbe exerts additional anthropogenic pressure. Biogeochemistry in the estuary is additionally governed by the North Sea and its strong tidal cycles, which ensure an exchange of fresh and marine waters.</p><p>The aims were to quantify the release of the carbon species total alkalinity (TA) and dissolved inorganic carbon (DIC) along the Elbe estuary, and to estimate the contribution of aerobe and anaerobe metabolic processes. Therefore, we used water samples collected continuously during a cruise in June 2019, to measure TA and DIC, and the stable isotopes of nitrate. We applied mass balances, to characterize the metabolic activity and detect their effect on the carbon species</p><p>The Elbe estuary could be subdivided into two parts: 1) an outer marine driven part, which is dominated by conservative mixing, also visible in higher TA than DIC values, and 2) an inner fresh water part in which metabolic processes play an important role.</p><p>We found a strong increase in TA and DIC (several hundred µmol kg<sup>-1</sup>) in the Hamburg port area, with higher DIC than TA values. We unraveled the water column impacts of nitrification and denitrification on TA and DIC by analyzing the stable isotopes δ<sup>15</sup>N-NO<sub>3</sub><sup>-</sup> and δ<sup>18</sup>O-NO<sub>3</sub><sup>-</sup>, and identified water column nitrification as a dominant pelagic process in the port of Hamburg and in the fresh water part further downstream. Because nitrification cannot explain the significant increase of TA and DIC in the port region, anaerobic processes such as denitrification in the sediment also appear to play an important role.</p><p> </p>

Modelling water column processes in the North Sea

1993 ◽  
Vol 343 (1669) ◽  
pp. 509-517 ◽  
Keyword(s):  
Water Column ◽  
North Sea ◽  
Process Water ◽  
Phytoplankton Dynamics ◽  
Annual Cycles ◽  
The North ◽  
Field Investigations ◽  
Southern Central ◽  
The North Sea ◽  
Northern North Sea

In the North Sea advective transports are not negligible. Nevertheless, physical properties like sea surface temperature (SST) can be hindcasted with sufficient precision by vertical process water column models. Annual cycles of SST in the southern, central, and northern North Sea can be simulated using physical upper layer models with relatively small RMS errors. For the Fladenground Experiment (FLEX’76) in the northern North Sea the RMS error is less 0.3 °C for the 2 months of the experiment. This justifies the initial use, at least, of vertical process water column models in simulations for investigating transfer processes in the planktonic ecosystem. Experiments have shown that the simulated entrainment velocities at the bottom of the mixed layer during summer are critically dependent on the resolution of the forcing variables. The effects of this resolution on the annual phytoplankton dynamics will be discussed. Phytoplankton dynamics are strongly influenced by those of the zooplankton, and vice versa. Several field investigations have shown that, seemingly, phytoplankton cannot sustain the observed stock of zooplankton in the northern North Sea: there exists a gap between the abundance of phytoplankton and the need for it to maintain the zooplankton. Revisiting FLEX’76, the simulations with water column models of increasing complexity concerning detritus suggest that pelagic detritus can fill the gap in food availability for the zooplankton. If it is assumed that the zooplankton feeds also on detritus, the zooplankton experiences no food shortage.

scholarly journals Vertical distribution of pre-settled sandeel (Ammodytes marinus) in the North Sea in relation to size and environmental variables

2003 ◽  
Vol 60 (6) ◽  
pp. 1342-1351 ◽  
Author(s):  
Henrik Jensen ◽  
Peter J Wright ◽  
Peter Munk
Keyword(s):  
Vertical Distribution ◽  
Water Column ◽  
North Sea ◽  
Distribution Patterns ◽  
Food Concentration ◽  
The North ◽  
Vertical Distributions ◽  
The North Sea ◽  
Drift Trajectory ◽  
Vertical Positioning

Abstract Vertical distribution patterns of larval and juvenile sandeels were investigated at four locations in the North Sea. Sandeels between 6 and 65 mm were found to depths of 80 m, with vertical distributions dependent on both length and environmental factors. At one location with a stratified water column, the highest densities were found during the day in midwater where food concentration was also highest. In areas without marked vertical hydrographic gradients, larvae were relatively more abundant in surface waters during the day. At all locations, larvae of all sizes were generally more homogeneously distributed in the water column during night than during day. The extent of vertical migration, as measured by the standard deviation of the mean depth, increased generally with length. Gear avoidance was evident for larvae ≥20 mm. Catch efficiency generally depended on both length class and surface light intensity. A simulated drift pattern of larvae, based on ADCP current measurements from two locations, predicts that the horizontal drift trajectory would only be affected slightly by the vertical positioning of the larvae in the water column during the time of sampling. The implication of vertical migrations for dispersal of larvae away from the spawning grounds is discussed.

scholarly journals Radium isotopes as a tracer of sediment-water column exchange in the North Sea

2014 ◽  
Vol 28 (8) ◽  
pp. 786-804 ◽  
Author(s):  
W. J. Burt ◽  
H. Thomas ◽  
J. Pätsch ◽  
A. M. Omar ◽  
C. Schrum ◽  
...  
Keyword(s):  
Water Column ◽  
North Sea ◽  
Radium Isotopes ◽  
The North ◽  
The North Sea

A comparative study of manganese dynamics in the water column and sediments of intertidal systems of the North Sea

2012 ◽  
Vol 100 ◽  
pp. 3-17 ◽  
Author(s):  
Nicole Kowalski ◽  
Olaf Dellwig ◽  
Melanie Beck ◽  
Maik Grunwald ◽  
Claus-Dieter Dürselen ◽  
...  
Keyword(s):  
Comparative Study ◽  
Water Column ◽  
North Sea ◽  
The North ◽  
The North Sea

scholarly journals The Marine Radiocarbon Bomb Pulse Across the Temperate North Atlantic: A Compilation of Δ14C Time Histories fromArctica IslandicaGrowth Increments

Radiocarbon ◽  
2012 ◽  
Vol 54 (2) ◽  
pp. 165-186 ◽  
Author(s):  
James D Scourse ◽  
Alan D Wanamaker ◽  
Chris Weidman ◽  
Jan Heinemeier ◽  
Paula J Reimer ◽  
...  
Keyword(s):  
North Sea ◽  
Marine Environment ◽  
Mixed Layer ◽  
North Atlantic ◽  
German Bight ◽  
Freshwater Flux ◽  
Arctica Islandica ◽  
Oyster Ground ◽  
Time Histories ◽  
Carbon Reservoir

Marine radiocarbon bomb-pulse time histories of annually resolved archives from temperate regions have been underexploited. We present here series of Δ14C excess from known-age annual increments of the long-lived bivalve molluskArctica islandicafrom 4 sites across the coastal North Atlantic (German Bight, North Sea; Troms⊘, north Norway; Siglufjordur, north Icelandic shelf; Grimsey, north Icelandic shelf) combined with published series from Georges Bank and Sable Bank (NW Atlantic) and the Oyster Ground (North Sea). The atmospheric bomb pulse is shown to be a step-function whose response in the marine environment is immediate but of smaller amplitude and which has a longer decay time as a result of the much larger marine carbon reservoir. Attenuation is determined by the regional hydrographic setting of the sites, vertical mixing, processes controlling the isotopic exchange of14C at the air-sea boundary,14C content of the freshwater flux, primary productivity, and the residence time of organic matter in the sediment mixed layer. The inventories form a sequence from high magnitude-early peak (German Bight) to low magnitude-late peak (Grimsey). All series show a rapid response to the increase in atmospheric Δ14C excess but a slow response to the subsequent decline resulting from the succession of rapid isotopic air-sea exchange followed by the more gradual isotopic equilibration in the mixed layer due to the variable marine carbon reservoir and incorporation of organic carbon from the sediment mixed layer. The data constitute calibration scries for the use of the bomb pulse as a high-resolution dating tool in the marine environment and as a tracer of coastal ocean water masses.

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