SUMIC: Multicomponent sea‐bottom seismic surveying in the North Sea—Data interpretation and applications

1994 ◽  
Author(s):  
Eivind Berg ◽  
Bjørnar Svenning ◽  
James Martin
Keyword(s):  
North Sea ◽  
Data Interpretation ◽  
The North ◽  
Sea Bottom ◽  
Seismic Surveying ◽  
The North Sea

scholarly journals Challenges in the Assessment of Bycatch: Postmortem Findings in Harbor Porpoises (Phocoena phocoena) Retrieved From Gillnets

2020 ◽  
pp. 030098582097245
Author(s):  
Lonneke L. IJsseldijk ◽  
Meike Scheidat ◽  
Marije L. Siemensma ◽  
Bram Couperus ◽  
Mardik F. Leopold ◽  
...  
Keyword(s):  
Health Status ◽  
North Sea ◽  
Electronic Monitoring ◽  
Nutritional Condition ◽  
Diagnostic Tools ◽  
Phocoena Phocoena ◽  
The North ◽  
Sea Bottom ◽  
The North Sea ◽  
Harbor Porpoises

Bycatch is considered one of the most significant threats affecting cetaceans worldwide. In the North Sea, bottom-set gillnets are a specific risk for harbor porpoises ( Phocoena phocoena). Methods to estimate bycatch rates include on-board observers, remote electronic monitoring, and fishermen voluntarily reporting; none of these are systematically conducted. Additionally, necropsies of stranded animals can provide insights into bycatch occurrence and health status of individuals. There are, however, uncertainties when it comes to the assessment of bycatch in stranded animals, mainly due to the lack of diagnostic tools specific for underwater entrapment. We conducted a literature review to establish criteria that aid in the assessment of bycatch in small cetaceans, and we tested which of these criteria applied to harbor porpoises retrieved from gillnets in the Netherlands ( n = 12). Twenty-five criteria were gathered from literature. Of these, “superficial incisions,” “encircling imprints,” and “recent ingestion of prey” were observed in the vast majority of our confirmed bycatch cases. Criteria like “pulmonary edema,” “pulmonary emphysema,” and “organ congestion” were also frequently observed, although considered unspecific as an indicator of bycatch. Notably, previously mentioned criteria as “favorable health status,” “absence of disease,” or “good nutritional condition” did not apply to the majority of our bycaught porpoises. This may reflect an overall reduced fitness of harbor porpoises inhabiting the southern North Sea or a higher chance of a debilitated porpoise being bycaught, and could result in an underestimation of bycatch rates when assessing stranded animals.

A bifacial tool of the Neanderthals from Ameland, the Netherlands

2013 ◽  
Vol 92 (2-3) ◽  
pp. 181-192 ◽  
Author(s):  
D. Stapert ◽  
L. Johansen ◽  
M.J.L.Th. Niekus
Keyword(s):  
The Netherlands ◽  
North Sea ◽  
Surface Modifications ◽  
Middle Palaeolithic ◽  
The North ◽  
Sea Bottom ◽  
The North Sea

AbstractA bifacially worked flint tool has recently been found on the North Sea beach of Ameland, one of the Wadden Islands in the northern Netherlands. It probably dates from the Middle Palaeolithic because its surface modifications include windgloss which in this area originated especially during the Weichselian Late Pleniglacial. The tool was probably first worked by a skilled knapper and subsequently, after a break occurred, by an apprentice. It is suggested that the tool was transported to Ameland from the North Sea bottom in the course of sand replenishment activities. Other artefacts from the Wadden Islands allegedly left by Neanderthals are also briefly discussed.

scholarly journals TRACER TESTS IN THE MIDDLE NORTH SEA

1974 ◽  
Vol 1 (14) ◽  
pp. 56
Author(s):  
E. Bratteland ◽  
P. Bruun
Keyword(s):  
North Sea ◽  
Coastal Waters ◽  
Tracer Tests ◽  
Main Interest ◽  
The North ◽  
Sea Bottom ◽  
The North Sea ◽  
Large Water ◽  
Water Depths ◽  
Shallow Coastal Waters

Tracing of sediment transport has so far mostly been concentrated in rivers and particularly in estuaries and in shallow coastal waters with main interest on navigational, erosional and some pollutionary aspects. With the ever increasing oil activites in the North Sea, knowledge on bottom sediment movements at large water depths is becoming more and more important. Little tracing has been undertaken on the offshore sea bottom at depths exceeding 20 - 30 meters.

scholarly journals Warm water occupancy by North Sea cod

2006 ◽  
Vol 274 (1611) ◽  
pp. 789-798 ◽  
Author(s):  
Francis Neat ◽  
David Righton
Keyword(s):  
North Sea ◽  
Large Scale ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Thermal Habitat ◽  
The North ◽  
Sea Bottom ◽  
The North Sea ◽  
Electronic Tagging ◽  
Number Of Individuals

The North Sea has warmed in recent years and there is an ongoing debate into how this is affecting the distribution of fishes and other marine organisms. Of particular interest is the commercially important Atlantic cod ( Gadus morhua L.), which has declined sharply in abundance in the North Sea over the past 20 years. Observations of the temperature experienced by 129 individual cod throughout the North Sea were made during a large-scale electronic tagging programme conducted between 1999 and 2005. We asked whether individual cod fully occupied the thermal habitat available to them. To this end, we compared the temperature experience of cod with independently measured contemporaneous sea-bottom temperature data. The majority of cod experienced a warmer fraction of the sea than was potentially available to them. By summer, most of the individuals in the south experienced temperatures considered superoptimal for growth. Cooler waters were within the reach of the cod and a small number of individuals migrated to areas that allowed them to experience lower temperatures, indicating that the cod had the capacity to find cooler water. Most did not, however, suggesting that the changing thermal regime of the North Sea is not yet causing adult cod to move to cooler waters.

Suspended particulate matter in the North Sea: field observations and model simulations

1993 ◽  
Vol 343 (1669) ◽  
pp. 423-430 ◽  
Keyword(s):  
Particulate Matter ◽  
North Sea ◽  
Suspended Particulate Matter ◽  
Three Dimensional ◽  
Lagrangian Model ◽  
The North ◽  
Sea Bottom ◽  
Suspended Particulate ◽  
The North Sea ◽  
Diffusive Fluxes

A major part of land ocean interaction in the coastal zone consists of the transport of suspended particulate matter (SPM). Its mass balance is determined by the input from rivers, atmosphere and adjacent seas, by advective and diffusive fluxes, and by deposition and resuspension at the sea bottom. For the North Sea, a three-dimensional lagrangian model has been developed which includes all these components. It is driven by the actual atmospheric forcing, the tides and the baroclinic currents. Model results of SPM spreading and deposition for specific years are presented and compared with in situ observations and satellite images.

Continuous plankton records: the geographical distribution and seasonal cycles of decapod crustacean larvae and pelagic post-larvae in the north-eastern Atlantic Ocean and the North Sea, 1981–3

1987 ◽  
Vol 67 (1) ◽  
pp. 145-167 ◽  
Author(s):  
J. A. Lindley
Keyword(s):  
North Sea ◽  
Decapod Crustacean ◽  
Seasonal Cycles ◽  
Larval Stages ◽  
The North ◽  
Sea Bottom ◽  
Eastern Atlantic Ocean ◽  
Pelagic Larvae ◽  
North Eastern ◽  
The North Sea

The geographical distributions and seasonal cycles of pelagic larvae and post-larval stages of decapod Crustacea in the north-eastern Atlantic and the North Sea during 1981–3 are described from samples taken with the Continuous Plankton Recorder (CPR). Analyses of the distributions of 36 common taxa identified groupings which could be related to depth and temperature. The seasonal occurrences of planktonic larvae of benthic taxa were found to be correlated with sea-bottom temperature in the winter as well as parameters of the sea-surface temperature. Possible interpretations of these data are discussed.

scholarly journals Geology of outer Horns Rev, Danish North Sea

2008 ◽  
Vol 15 ◽  
pp. 41-44
Author(s):  
Jørn Bo Jensen ◽  
Peter Gravesen ◽  
Steen Lomholt
Keyword(s):  
North Sea ◽  
Wind Farm ◽  
Offshore Wind ◽  
Side Scan Sonar ◽  
Cone Penetration Tests ◽  
The North ◽  
Complex Information ◽  
Sea Bottom ◽  
Sea Bed ◽  
The North Sea

In 2006, Dong Energy initiated the development of the Horns Rev II offshore wind farm in the North Sea (Fig. 1). In order to evaluate and map the characteristics of the surface features of the sea bed and to characterise the subsurface in the wind farm area, the Geological Survey of Denmark and Greenland (GEUS) conducted a geophysical survey of the area. The survey utilised a variety of instruments: sparker, side-scan sonar, marine caesium magnetometer and a multibeam echo-sounder. In addition, information on the subsurface sediments was obtained by cone penetration tests (CPT) and by drilling to 30–50 m below the sea bottom. Geological correlation of the CPT results with the other survey results was extremely complicated but was required in order to understand the architecture of the ice marginal glaciotectonic complex. Information on the geology is crucial for evaluation of the geotechnical problems of the region.

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