scholarly journals Monitoring juvenile stocks of flatfish in the Wadden Sea and the coastal areas of the southeastern North Sea

1989 ◽  
Vol 43 (3-4) ◽  
pp. 461-477 ◽  
Author(s):  
F. A. Beek ◽  
A. D. Rijnsdorp ◽  
R. Clerck
Keyword(s):  
North Sea ◽  
Wadden Sea ◽  
Coastal Areas

scholarly journals Reef-building Pacific oysters record seasonal variations in water mass-properties of tidal basins from the Central Wadden Sea (North Sea)

2021 ◽  
pp. 110534
Author(s):  
Jassin Petersen ◽  
Jürgen Titschack ◽  
Jeroen Groeneveld ◽  
Achim Wehrmann ◽  
Dierk Hebbeln ◽  
...  
Keyword(s):  
North Sea ◽  
Seasonal Variations ◽  
Wadden Sea ◽  
Water Mass ◽  
Pacific Oysters ◽  
Tidal Basins ◽  
Mass Properties

scholarly journals Inventory and comparison of abundance of parasitic copepods on fish hosts in the western Wadden Sea (North Sea) between 1968 and 2010

2013 ◽  
Vol 94 (3) ◽  
pp. 547-555 ◽  
Author(s):  
Wouter Koch ◽  
Peter Boer ◽  
Johannes IJ. Witte ◽  
Henk W. Van der Veer ◽  
David W. Thieltges
Keyword(s):  
North Sea ◽  
Wadden Sea ◽  
Temporal Stability ◽  
Parasite Fauna ◽  
Fixed Number ◽  
Fish Host ◽  
Host Size ◽  
Negative Effects ◽  
Parasitic Copepods ◽  
Fish Hosts

A conspicuous part of the parasite fauna of marine fish are ectoparasites, which attach mainly to the fins or gills. The abundant copepods have received much interest due to their negative effects on hosts. However, for many localities the copepod fauna of fish is still poorly known, and we know little about their temporal stability as long-term observations are largely absent. Our study provides the first inventory of ectoparasitic copepods on fish from the western Wadden Sea (North Sea) based on field data from 1968 and 2010 and additional unpublished notes. In total, 47 copepod parasite species have been recorded on 52 fish host species to date. For two copepod species parasitizing the European flounder (Platichthys flesus), a quantitative comparison of infection levels between 1968 and 2010 was possible. Whereas Acanthochondria cornuta did not show a change in the relationship between host size and infection levels, Lepeophtheirus pectoralis shifted towards the infection of smaller hosts, with higher infection levels in 2010 compared to 1968. These differences probably reflect the biology of the species and the observed decrease in abundance and size of flounders during the last decades. The skin-infecting L. pectoralis can probably compensate for dwindling host abundance by infecting smaller fish and increasing its abundance per given host size. In contrast, the gill cavity inhabiting A. cornuta probably faces a spatial constraint (fixed number of gill arches), thus limiting its abundance and setting a minimum for the host size necessary for infections.

scholarly journals Living and dead foraminiferal assemblage from the supratidal sand Japsand, North Frisian Wadden Sea: distributional patterns and controlling factors

2021 ◽  
Vol 75 (1) ◽  
Author(s):  
Sarina Schmidt ◽  
Joachim Schönfeld
Keyword(s):  
North Sea ◽  
Wadden Sea ◽  
Distribution Patterns ◽  
Abundant Species ◽  
Foraminiferal Assemblage ◽  
The North ◽  
Key Species ◽  
Reproduction Season ◽  
The Dead ◽  
Reproductive Cycles

AbstractSupratidal sands are vitally important for coastal defence in the German Wadden Sea. They are less affected by human activities than other areas as they are located far off the mainland shore, touristical and commercial activities are generally prohibited. Therefore, supratidal sands are of high ecological interest. Nevertheless, the faunal inventory and distribution pattern of microorganisms on these sands were studied very little. The composition of living and dead foraminiferal assemblages was therefore investigated along a transect from the supratidal sand Japsand up to Hallig Hooge. Both assemblages were dominated by calcareous foraminifera of which Ammonia batava was the most abundant species. Elphidium selseyense and Elphidium williamsoni were also common in the living assemblage, but Elphidium williamsoni was comparably rare in the dead assemblage. The high proportions of Ammonia batava and Elphidium selseyense in the living assemblage arose from the reproduction season that differed between species. While Ammonia batava and Elphidium selseyense just finished their reproductive cycles, Elphidium williamsoni was just about to start. This was also confirmed by the size distribution patterns of the different species. The dead assemblage revealed 20 species that were not found in the living assemblage of which some were reworked from older sediments (e.g., Bucella frigida) and some were transported via tidal currents from other areas in the North Sea (e.g., Jadammina macrescens). The living foraminiferal faunas depicted close linkages between the open North Sea and the mainland. Key species revealing exchange between distant populations were Haynesina germanica, Ammonia batava and different Elphidium species. All these species share an opportunistic behaviour and are able to inhabit a variety of different environments; hence, they well may cope with changing environmental conditions. The benthic foraminiferal association from Japsand revealed that transport mechanisms via tides and currents play a major ecological role and strongly influence the faunal composition at this site.

Afsluitdijk climate resilient with XblocPlus

2021 ◽  
Author(s):  
Bas Reedijk ◽  
Pieter Bakker
Keyword(s):  
Climate Change ◽  
Sea Level ◽  
North Sea ◽  
Wadden Sea ◽  
Water Levels ◽  
Visual Appearance ◽  
Seaward Side ◽  
Reference Design ◽  
Wave Heights ◽  
Crest Height

<p>The Afsluitdijk forms 32 km of the primary sea defence of the Netherlands. The Afsluitdijk was built as a closure dam in 1932 and separates the IJsselmeer from the Wadden-Sea and North Sea. Because of climate change the Afsluitdijk needs to be strengthened. A higher crest height is required to limit overtopping at higher water levels due to sea level rise. Heavier armour is required to protect the Afsluitdijk from higher wave heights. Because of the historic value of the Afsluitdijk, stringent architectural requirements are in place on the visual appearance of the dam after strengthening [1]. Therefore, a new concrete armour unit was developed to provide protection of the seaward side of the Afsluitdijk. This armour unit is called XblocPlus. The development of the armour unit is based on the breakwater armour unit Xbloc which has been applied since 2004. A saving of 56% on CO2 footprint was achieved compared to the Clients reference design.</p>

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.

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

Long-term changes in species composition of demersal fish and epibenthic species in the Jade area (German Wadden Sea/Southern North Sea) since 1972

2016 ◽  
Vol 181 ◽  
pp. 284-293 ◽  
Author(s):  
Julia Meyer ◽  
Ingrid Kröncke ◽  
Alexander Bartholomä ◽  
Joachim W. Dippner ◽  
Ulrike Schückel
Keyword(s):  
Species Composition ◽  
North Sea ◽  
Wadden Sea ◽  
Demersal Fish ◽  
Southern North Sea ◽  
Long Term Changes
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