scholarly journals Conservation Implications of Sabellaria spinulosa Reef Patches in a Dynamic Sandy-Bottom Environment

2021 ◽  
Vol 8 ◽  
Author(s):  
Karin J. van der Reijden ◽  
Leo Koop ◽  
Sebastiaan Mestdagh ◽  
Mirjam Snellen ◽  
Peter M. J. Herman ◽  
...  
Keyword(s):  
Multiple Scales ◽  
Conservation Status ◽  
Small Scale ◽  
Ecological Value ◽  
Sandy Bottom ◽  
The North ◽  
Conservation Implications ◽  
The North Sea ◽  
The Stability ◽  
Video Transect

Biogenic reefs form biodiversity hotspots and are key components of marine ecosystems, making them priority habitats for nature conservation. However, the conservation status of biogenic reefs generally depends on their size and stability. Dynamic, patchy reefs may therefore be excluded from protection. Here, we studied epibenthos and epifauna density, richness, and community composition of patchy, dynamic Sabellaria spinulosa (ross worm) reefs in the North Sea. This study was conducted by comparing boxcore (endobenthos) and video transect (epifauna) data from two research campaigns in 2017 and 2019 to the Brown Bank area on the Dutch Continental Shelf, where S. spinulosa reefs were first discovered in 2017. The Brown Bank area is characterized by dynamic, migratory bedforms at multiple scales which potentially affect biogenic reef stability. We showed that S. spinulosa habitats had a patchy distribution and alternated with habitats comprised of plain sand. Average S. spinulosa habitat patch size was 5.57 ± 0.99 m and 3.94 ± 0.22 m in 2017 and 2019, respectively (mean ± SE), which especially in 2019 closely resembled the small-scale megaripple bedforms. Contrary to the endobenthos communities that were unaffected by S. spinulosa, epifauna density and species richness were at least two times higher in S. spinulosa habitats compared to sandy habitats, resulting in different community compositions between the two habitat types. We showed that S. spinulosa persisted in the area for almost 2 years. Although the stability of individual patches remained unclear, we demonstrated that even patchy biogenic reefs may promote density and local biodiversity of mobile, epibenthic species, very likely as a result of increased habitat heterogeneity provided by reef habitat patches. This indicates that patchy biogenic reefs that occur in dynamic environments may also have high ecological value and their conservation status should be (re)considered to ensure their protection.

On submarine sand-waves and tidal lee-waves

1959 ◽  
Vol 253 (1273) ◽  
pp. 218-241 ◽  
Keyword(s):  
Wave Train ◽  
Tidal Flow ◽  
Stationary Wave ◽  
Slow Phase ◽  
Density Gradients ◽  
Sand Waves ◽  
The North ◽  
Lee Waves ◽  
The North Sea ◽  
The Stability

A simplified analysis is made of the stability of long waves in a sand bed under deep, slow, and steady (or slowly varying) water flow. Allowing for vertical variation in density and shear, the linearized hydrodynamical equations yield a symmetrical flow whose only action is to impart a slow phase velocity to existing sand-waves without altering their amplitude. The only mechanism found under which sand-waves could grow under the assumed conditions is that of a stationary wave train in the lee of a permanent obstacle. The lee-waves require density gradients greater than a certain minimum, independently of any stability due to shear. Application of this model to tidal flow in the Summer thermocline over the Continental Shelf west of Brittany yields a spectrum of wave-building increments which agrees in general wavelength and shape with that of sand-waves measured on La Chapelle Bank (47° 41' N, 7° 13' W). Changes in amplitude of a few sand-grain diameters per year would be expected. Thermal stratification would be insufficient for the same mechanism to generate waves in the North Sea, but the possibility of density gradients due to suspended sediment is suggested as a likely factor of importance.

scholarly journals Editorial

2018 ◽  
Vol 97 (3) ◽  
pp. 69-70
Author(s):  
Ad J.F. van der Spek ◽  
Niels van den Berg
Keyword(s):  
Salt Marshes ◽  
Wadden Sea ◽  
Barrier Islands ◽  
Natural Process ◽  
Tidal Channels ◽  
Ecological Value ◽  
The North ◽  
Wide Range ◽  
The North Sea ◽  
A Chain

The Wadden Sea region spans a distance of nearly 500km along the North Sea coast from the Netherlands to Denmark. It consists of a chain of barrier islands which shelter an area of extensive intertidal flats and salt marshes that are dissected by tidal channels and creeks. Moreover, several estuaries are part of this area which is known for its intriguing morphodynamics. The natural process of continuous erosion, transport and deposition of sediment shapes the morphology of the area, which has a high ecological value, especially the intertidal morphology that supports a wide range of wildlife.

Management of Dutch Estuaries the Ems-Dollard and the Western Scheldt

1992 ◽  
Vol 26 (7-8) ◽  
pp. 1887-1896 ◽  
Author(s):  
P. H. A. Hoogweg ◽  
F. Colijn
Keyword(s):  
Biological Diversity ◽  
Action Plan ◽  
Management Problem ◽  
Ecological Situation ◽  
Ecological Value ◽  
The North ◽  
International Consultation ◽  
Ecological Values ◽  
The North Sea ◽  
The Government

In this paper the ecological situation of two Dutch estuaries will be described in relation to efforts of the Government to maintain or restore their environmental quality. The two estuaries are the Ems-Dollard estuary and the Western Scheldt. Both form the border with Germany and Belgium respectively and therefore are a potential management problem with respect to pollution crossing the borders between the countries involved. Therefore international consultation is needed to tackle environmental problems. Both estuaries are the remaining real estuaries of the Netherlands which can be conceived as one large Delta region of the rivers Rhine, Meuse, Scheldt and Ems. Plans for the sanitation of all rivers have been proposed and are in development as e.g. the Rhine Action Plan. For the smaller rivers like the Ems and Scheldt agreements about the reduction of pollutants have been made within the framework of the North Sea ministerial conferences. The ecological values of these estuaries are diminished through pollution, resulting in a reduced biological diversity, or reduced numbers of species. At present measures are taken to improve the ecological value which is based on the former ecological situation (ten Brink et al., 1991). Besides pollution also dredging and dumping of dredged material has levelled down the biological diversity and numbers of plants and animals.

scholarly journals Small-scale spatial structuring of burrowed sandeels and the catching properties of the dredge

2013 ◽  
Vol 70 (2) ◽  
pp. 379-386 ◽  
Author(s):  
Espen Johnsen ◽  
Alf Harbitz
Keyword(s):  
Large Scale ◽  
Spatial Models ◽  
Small Scale ◽  
The North ◽  
Gamma Distributions ◽  
Abundance Estimates ◽  
Efficient Sampling ◽  
Spatial Structuring ◽  
The North Sea ◽  
Catch Rates

Abstract Johnsen, E., and Harbitz, A. 2013. Small-scale spatial structuring of burrowed sandeels and the catching properties of the dredge – ICES Journal of Marine Science, 70: 379–386. The lesser sandeel (Ammodytes marinus) remains burrowed for long periods in the seabed in sandy areas, and its habitat preference is reflected in a large-scale (10 km) patchy distribution in the North Sea. The small-scale spatial structure of sandeels in the seabed is less known. In this study, it was found that sandeel catches in grabs and dredges fit gamma distributions with a common shape parameter on both a 10 m and a 100 m scale. These spatial models were used to examine the catching properties of the dredge, which, in the new ICES sandeel assessment, is used to estimate recruitment and maturity curves. Analyses of the empirical data and simulations of the dredge and grab catch rates show very low dredge catchability (∼5%), but no length-dependent catchability in the dredge was found. However, analyses of the catch rates of parallel dredge hauls indicated increasing dredge catchability with sandeel density. The observed small-scale patchiness and the low and seemingly density-dependent dredge catchability result in biased abundance estimates with low precision. Therefore, we recommend a joint international effort to develop a more catch-efficient sampling dredge, where the effect of density on catchability is further examined.

scholarly journals WRF Model Methodology for Offshore Wind Energy Applications

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Evangelia-Maria Giannakopoulou ◽  
Regis Nhili
Keyword(s):  
Wind Energy ◽  
North Sea ◽  
Wrf Model ◽  
Offshore Wind ◽  
Stability Conditions ◽  
Validation Process ◽  
Energy Applications ◽  
The North ◽  
The North Sea ◽  
The Stability

Among the parameters that must be considered for an offshore wind farm development, the stability conditions of the marine atmospheric boundary layer (MABL) are of significant importance. Atmospheric stability is a vital parameter in wind resource assessment (WRA) due to its direct relation to wind and turbulence profiles. A better understanding of the stability conditions occurring offshore and of the interaction between MABL and wind turbines is needed. Accurate simulations of the offshore wind and stability conditions using mesoscale modelling techniques can lead to a more precise WRA. However, the use of any mesoscale model for wind energy applications requires a proper validation process to understand the accuracy and limitations of the model. For this validation process, the weather research and forecasting (WRF) model has been applied over the North Sea during March 2005. The sensitivity of the WRF model performance to the use of different horizontal resolutions, input datasets, PBL parameterisations, and nesting options was examined. Comparison of the model results with other modelling studies and with high quality observations recorded at the offshore measurement platform FINO1 showed that the ERA-Interim reanalysis data in combination with the 2.5-level MYNN PBL scheme satisfactorily simulate the MABL over the North Sea.

scholarly journals Impact of additional small-scale survey data on the geostatistical analyses of demersal fish species in the North Sea

2005 ◽  
Vol 69 (4) ◽  
pp. 587-602 ◽  
Author(s):  
Gerd Peter Zauke ◽  
Vanessa Stelzenmüller ◽  
Siegfried Ehrich
Keyword(s):  
Survey Data ◽  
North Sea ◽  
Fish Species ◽  
Demersal Fish ◽  
Small Scale ◽  
The North ◽  
The North Sea

scholarly journals JOINT OFFSHORE WIND FIELD MONITORING WITH SPACEBORNE SAR AND PLATFORM-BASED DOPPLER LIDAR MEASUREMENTS

2015 ◽  
Vol XL-7/W3 ◽  
pp. 959-966 ◽  
Author(s):  
S. Jacobsen ◽  
S. Lehner ◽  
J. Hieronimus ◽  
J. Schneemann ◽  
M. Kühn
Keyword(s):  
North Sea ◽  
Wind Field ◽  
Wind Farm ◽  
Offshore Wind ◽  
Small Scale ◽  
Doppler Lidar ◽  
Wind Fields ◽  
The North ◽  
Spatial Coverage ◽  
The North Sea

The increasing demand for renewable energy resources has promoted the construction of offshore wind farms e.g. in the North Sea. While the wind farm layout consists of an array of large turbines, the interrelation of wind turbine wakes with the remaining array is of substantial interest. The downstream spatial evolution of turbulent wind turbine wakes is very complex and depends on manifold parameters such as wind speed, wind direction and ambient atmospheric stability conditions. <br><br> To complement and validate existing numerical models, corresponding observations are needed. While in-situ measurements with e.g. anemometers provide a time-series at the given location, the merits of ground-based and space- or airborne remote sensing techniques are indisputable in terms of spatial coverage. Active microwave devices, such as Scatterometer and Synthetic Aperture Radar (SAR), have proven their capabilities of providing sea surface wind measurements and particularly SAR images reveal wind variations at a high spatial resolution while retaining the large coverage area. Platform-based Doppler LiDAR can resolve wind fields with a high spatial coverage and repetition rates of seconds to minutes. In order to study the capabilities of both methods for the investigation of small scale wind field structures, we present a direct comparison of observations obtained by high resolution TerraSAR-X (TS-X) X-band SAR data and platform-based LiDAR devices at the North Sea wind farm alpha ventus. We furthermore compare the results with meteorological data from the COSMO-DE model run by the German Weather Service DWD. Our study indicates that the overall agreement between SAR and LiDAR wind fields is good and that under appropriate conditions small scale wind field variations compare significantly well.

AN ENVIRONMENTAL IMPACT STUDY AND POLLUTION CONTINGENCY PLAN FOR AN ECOLOGICALLY SENSITIVE AREA IN THE NORTH SEA

1983 ◽  
Vol 1983 (1) ◽  
pp. 135-141
Author(s):  
T. G. Wilkinson ◽  
R. McEwan
Keyword(s):  
Oil Spills ◽  
Sensitive Area ◽  
Ecological Value ◽  
Contingency Plan ◽  
The North ◽  
Emergency Response Plan ◽  
Moray Firth ◽  
The North Sea ◽  
Exact Position ◽  
Operational Practices

ABSTRACT The hub of the Moray Firth is a large sheltered estuary of intertidal mud flats. This estuary is surrounded on both sides by some 100 kilometers (km) of exposed cliffs and beaches. Ecological surveys have been conducted, in-house operations have responded to the study, and a pollution emergency response plan has been developed for the proposed 1983 exploration programme. The mud flats and salt marsh habitats in the inner estuary are of wide ecological value and are, for example, the most important sites in the U.K. for overwintering seaduck populations. They are particularly sensitive from October to February. The exposed coast is, on the other hand, particularly sensitive from February to October because of seabirds breeding (e.g., auks), inshore lobster and crab fishing and inshore salmon netting. Such a sensitive area calls for specific pre-planning and operational controls. SLIKTRAK model predictions have shown that there is statistically a good chance of polluting the exposed coast line from the proposed drilling location, whereas the chance of hitting the inner estuary is shown to be very low. Drilling and sensitive workover operations have, therefore, been scheduled to take place over winter when the effect of an oil spill which could hit the exposed coasts would be very much less. Operational practices also have been critically reviewed. A tailored contingency plan has been developed. This will include an at-sea cleanup capability consisting of dispersant spraying equipment and a boom pick-up system for dealing with operational diesel spills. During a spill, pre-tested tracker buoys will be used to monitor the exact position of the spill, and a pre-tested computer model will be used to predict where the spill is going to ensure preparedness on shore. A monitoring programme is being developed for both the shoreline (for oil spills) and the local marine environment (for chronic pollution). Only limited treatment is possible onshore, such as by booming harbours or by selective dispersant application. Liaison with industry, local authorities, and communities is part of the plan.

Bioaccumulation and effects of PCBs and heavy metals in sea stars (Asterias rubens, L.) from the North Sea: A small scale perspective

2006 ◽  
Vol 356 (1-3) ◽  
pp. 275-289 ◽  
Author(s):  
B DANIS ◽  
P WANTIER ◽  
R FLAMMANG ◽  
P PERNET ◽  
Y CHAMBOSTMANCIET ◽  
...  
Keyword(s):  
Heavy Metals ◽  
North Sea ◽  
Small Scale ◽  
Asterias Rubens ◽  
Sea Stars ◽  
The North ◽  
The North Sea
Sign in / Sign up

Export Citation Format

Share Document