scholarly journals Tidal-current transport of thread-drifting postlarval juveniles of the bivalve Macoma balthica from the Wadden Sea to the North Sea

1989 ◽  
Vol 52 ◽  
pp. 193-200 ◽  
Author(s):  
JJ Beukema ◽  
J de Vlas
Keyword(s):  
North Sea ◽  
Tidal Current ◽  
Wadden Sea ◽  
Macoma Balthica ◽  
Current Transport ◽  
The North ◽  
The North Sea

Sources and Fate of PCBs in the North Sea: A Review of Available Data

1991 ◽  
Vol 24 (10) ◽  
pp. 77-85 ◽  
Author(s):  
J. Klamer ◽  
R. W. P. M. Laane ◽  
J. M. Marquenie
Keyword(s):  
Adverse Effects ◽  
North Sea ◽  
German Bight ◽  
Marine Mammals ◽  
Wadden Sea ◽  
Annual Basis ◽  
The North ◽  
Total Input ◽  
Seal Population ◽  
The North Sea

From literature data it is calculated that on an annual basis, 11 to 17 tonnes of PCBs enter the North Sea. Largest sources are the Atlantic Ocean and the atmosphere: together they account for 60-79% of the total input. Sources with greatest impact are the rivers, sewers and sludge. Highest concentrations are found close to the Dutch shore and in the German Bight. The PCB levels result in adverse effects on the seal population in the Wadden Sea. Of the total world PCB production, at least 57% is still in use and their future dispersal into the oceans cannot easily be controlled. If the increase in ocean PCB concentration continues, it may ultimately result in the extinction of fish-eating marine mammals.

scholarly journals Large-scale forcing of the European Slope Current and associated inflows to the North Sea

Ocean Science ◽  
2017 ◽  
Vol 13 (2) ◽  
pp. 315-335 ◽  
Author(s):  
Robert Marsh ◽  
Ivan D. Haigh ◽  
Stuart A. Cunningham ◽  
Mark E. Inall ◽  
Marie Porter ◽  
...  
Keyword(s):  
Sea Level ◽  
North Sea ◽  
Tide Gauge ◽  
Density Gradients ◽  
Current Transport ◽  
Tide Gauge Records ◽  
The North ◽  
Wide Range ◽  
The North Sea ◽  
Northern North Sea

Abstract. The European Slope Current provides a shelf-edge conduit for Atlantic Water, a substantial fraction of which is destined for the northern North Sea, with implications for regional hydrography and ecosystems. Drifters drogued at 50 m in the European Slope Current at the Hebridean shelf break follow a wide range of pathways, indicating highly variable Atlantic inflow to the North Sea. Slope Current pathways, timescales and transports over 1988–2007 are further quantified in an eddy-resolving ocean model hindcast. Particle trajectories calculated with model currents indicate that Slope Current water is largely recruited from the eastern subpolar North Atlantic. Observations of absolute dynamic topography and climatological density support theoretical expectations that Slope Current transport is to first order associated with meridional density gradients in the eastern subpolar gyre, which support a geostrophic inflow towards the slope. In the model hindcast, Slope Current transport variability is dominated by abrupt 25–50 % reductions of these density gradients over 1996–1998. Concurrent changes in wind forcing, expressed in terms of density gradients, act in the same sense to reduce Slope Current transport. This indicates that coordinated regional changes of buoyancy and wind forcing acted together to reduce Slope Current transport during the 1990s. Particle trajectories further show that 10–40 % of Slope Current water is destined for the northern North Sea within 6 months of passing to the west of Scotland, with a general decline in this percentage over 1988–2007. Salinities in the Slope Current correspondingly decreased, evidenced in ocean analysis data. Further to the north, in the Atlantic Water conveyed by the Slope Current through the Faroe–Shetland Channel (FSC), salinity is observed to increase over this period while declining in the hindcast. The observed trend may have broadly compensated for a decline in the Atlantic inflow, limiting salinity changes in the northern North Sea during this period. Proxies for both Slope Current transport and Atlantic inflow to the North Sea are sought in sea level height differences across the FSC and between Shetland and the Scottish mainland (Wick). Variability of Slope Current transport on a wide range of timescales, from seasonal to multi-decadal, is implicit in sea level differences between Lerwick (Shetland) and Tórshavn (Faroes), in both tide gauge records from 1957 and a longer model hindcast spanning 1958–2012. Wick–Lerwick sea level differences in tide gauge records from 1965 indicate considerable decadal variability in the Fair Isle Current transport that dominates Atlantic inflow to the northwest North Sea, while sea level differences in the hindcast are dominated by strong seasonal variability. Uncertainties in the Wick tide gauge record limit confidence in this proxy.

Thalassiosiraspecies (Bacillariophyceae, Thalassiosirales) in the North Sea at Helgoland (German Bight) and Sylt (North Frisian Wadden Sea) – a first approach to assessing diversity

2007 ◽  
Vol 42 (3) ◽  
pp. 271-288 ◽  
Author(s):  
Mona Hoppenrath ◽  
Bank Beszteri ◽  
Gerhard Drebes ◽  
Hannelore Halliger ◽  
Justus E. E. Van Beusekom ◽  
...  
Keyword(s):  
North Sea ◽  
German Bight ◽  
Wadden Sea ◽  
The North ◽  
The North Sea ◽  
North Frisian

scholarly journals Historical changes in the benthos of the Wadden Sea around the island of Sylt in the North Sea

1989 ◽  
Vol 43 (3-4) ◽  
pp. 417-433 ◽  
Author(s):  
Karsten Reise ◽  
Elisabeth Herre ◽  
Manfred Sturm
Keyword(s):  
North Sea ◽  
Wadden Sea ◽  
Historical Changes ◽  
The North ◽  
The North Sea

Local and remote response of the North Sea dynamics to morphodynamic changes in the Wadden Sea

2016 ◽  
Vol 66 (5) ◽  
pp. 671-690 ◽  
Author(s):  
Benjamin Jacob ◽  
Emil Vassilev Stanev ◽  
Yinglong Joseph Zhang
Keyword(s):  
North Sea ◽  
Wadden Sea ◽  
The North ◽  
The North Sea ◽  
Remote Response

Observatory in the Wadden Sea: Nutrient cycling and export to the North Sea

2009 ◽  
Author(s):  
M. Beck ◽  
M. Grunwald ◽  
C. Kohlmeier ◽  
O. Dellwig ◽  
H.-J. Brumsack
Keyword(s):  
Nutrient Cycling ◽  
North Sea ◽  
Wadden Sea ◽  
The North ◽  
The North Sea

Danish–German–Dutch Wadden Environments

2005 ◽  
Author(s):  
Jacobus Hofstede
Keyword(s):  
Present State ◽  
North Sea ◽  
Energy Input ◽  
Wadden Sea ◽  
Wind Waves ◽  
Tidal Energy ◽  
Point Of View ◽  
Energy Impact ◽  
The North ◽  
The North Sea

The Wadden Sea environment is a coastal tidal environment situated between the North Sea and the northwestern European Lowlands. It stretches over a distance of about 450 km from Den Helder in The Netherlands to the peninsula of Skallingen in Denmark. The approximately 10,000 km2 large Wadden Sea is a coastal sediment sink that developed in the course of the Holocene transgression. It resulted from a specific combination of sediment availability (mainly from the North Sea) and a hydrodynamic regime of tides and waves. In its present state, the Wadden Sea environment consists of extensive tidal flats (the wadden), tidal gullies and inlets, salt marshes, and about twenty-four sandy barrier islands. Further, four estuaries exist that discharge into the Wadden Sea. The Wadden Sea may best be characterized by the words ‘dynamic’ and ‘extreme’; dynamic from a geo-morphological point of view, extreme in its biology. According to Spiegel (1997), with each flood phase a tidal energy input in the order of 2.2 thousand MW occurs in the Wadden Sea of Schleswig-Holstein (Germany). This energy input, combined with the energy impact of wind, waves, and storm surges, results in strong morphological processes. Flora and fauna in the Wadden Sea have to adapt to these intense morphodynamics. Further, they have to endure the permanent change of flood and ebb and fluctuations in salinity, as well as high water temperatures during summer and occasional ice cover during winter. As a result of these extreme environmental conditions, a highly specialized biosystem with about 4,800 species has developed (Heydemann 1998). In its present state the Wadden Sea is one of the last remaining near-natural large-scale ecosystems in central Europe. Its ecological significance is underlined by the fact that 250 animal species live exclusively here (Heydemann 1998). Furthermore, nowhere else in Europe is an ecosystem of this size visited by more birds per surface area for the purpose of feeding. However, the Wadden Sea is subjected to considerable human influences, e.g. the input of nutrients and pollutants, fisheries, dredging, boat traffic, and tourism (de Jong et al. 1999).

scholarly journals Heading northward to Scandinavia: Undaria pinnatifida in the northern Wadden Sea

2018 ◽  
Vol 61 (4) ◽  
pp. 365-371 ◽  
Author(s):  
Jessica Schiller ◽  
Dagmar Lackschewitz ◽  
Christian Buschbaum ◽  
Karsten Reise ◽  
Shaojun Pang ◽  
...  
Keyword(s):  
North Sea ◽  
Wadden Sea ◽  
Undaria Pinnatifida ◽  
Atlantic Coast ◽  
The North ◽  
Pacific Oysters ◽  
The North Sea ◽  
New Generation ◽  
Thallus Length ◽  
Natural Means

Abstract The kelp Undaria pinnatifida, native to East Asian shores, was unintentionally introduced with Pacific oysters into the Mediterranean in 1971. Intentional introduction from there to the French Atlantic coast 12 years later led to a gradual spread to the British Isles and the North Sea. Here, we report on the northernmost established population in continental Europe, and suggest a further spread into Scandinavian waters to be almost inevitable. In 2016, several thalli were found washed ashore at the eastern side of the island of Sylt in the northern Wadden Sea (German Bight, Eastern North Sea). Most specimens bore fertile sporophylls and thallus lengths of >1 m were common. In June 2017, 91 sporophytes were found attached to a mixed bed of Pacific oysters and native blue mussels, located just below low tide level in a moderately sheltered position. Mean thallus length was 0.2 m and the longest 0.7 m. Most had distinctive sporophylls and released spores in the laboratory. From sporophylls collected in the previous year, we successfully reared a new generation, demonstrating the kelp’s potential for further spread by natural means or human vectors.

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