scholarly journals Influence of spatial scales of observation on temporal change in diversity and trophic structure of fine-sand communities from the English Channel and the southern North Sea

2000 ◽  
Vol 57 (5) ◽  
pp. 1481-1487 ◽  
Author(s):  
K Ghertsos
Keyword(s):  
North Sea ◽  
Trophic Structure ◽  
Temporal Change ◽  
Spatial Scales ◽  
Fine Sand ◽  
English Channel ◽  
Southern North Sea

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 Investigations Upon the Water Movements in the English Channel. Summer, 1924

1927 ◽  
Vol 14 (3) ◽  
pp. 685-721 ◽  
Author(s):  
J. N. Carruthers
Keyword(s):  
North Sea ◽  
English Channel ◽  
Average Speed ◽  
Southern North Sea ◽  
The North ◽  
Westerly Winds ◽  
The North Sea

In July, 1924, 250 floating, and an equal number of bottom-trailing, bottles were put out at selected places in the western English Channel. Fifty of each type were put out at each of the two routine Stations E2 and E3, and the same number was “liberated” at each of three selected stretches along the steamship route from Southampton to St. Malo. Those surface bottles, which did not strand locally, travelled rapidly up Channel towards the North Sea and across it. Many bottles arrived in the Skager-Rack after performing their journey of some 700 miles at the rate of 6 miles a day and more. An adequate study of wind conditions, as recorded at several stations along the length of the Channel and at one station in the southern North Sea, revealed the fact that there was, for some 5½ months (counting from the time of liberation of the bottles), an almost uninterrupted predominance of south-westerly winds—as recorded at all stations considered. The whole area of the Channel was swept by south-westerly winds of average speed of some 9 miles a day for at least 5½ months subsequent to the time of putting out of the bottles. July, 1924, had (according to the Falmouth Observatory records) the largest proportion of westerly winds experienced for 54 years; 20 days of this month had winds with westerly components. The association of the unusually persistent westerly winds with the rapid travel of surface bottles towards and across the North Sea is interesting.

Movements and distribution of cod (Gadus morhua) in the southern North Sea and English Channel: results from conventional and electronic tagging experiments

2007 ◽  
Vol 87 (2) ◽  
pp. 599-613 ◽  
Author(s):  
David Righton ◽  
Victoria Anne Quayle ◽  
Stuart Hetherington ◽  
Gary Burt
Keyword(s):  
North Sea ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
English Channel ◽  
Seasonal Movement ◽  
Southern North Sea ◽  
The North ◽  
Fisheries Policy ◽  
The Uk ◽  
Electronic Tags

The sub-structure of Atlantic cod (Gadus morhua) stocks in the North Sea has important consequences for fisheries management as the Common Fisheries Policy moves towards a more regional approach. We investigated the movements, distribution and behaviour of cod in the southern North Sea (ICES IVc) and English Channel (ICES VIId) by re-analysing historic data from conventional tagging experiments, and by conducting new experiments with electronic tags. Cod tagged and released in IVc showed a northwards shift in distribution during the feeding season consistent with a homing migration away from spawning grounds along the coasts of the UK and the Netherlands. In contrast, cod tagged and released in VIId did not exhibit a consistent pattern of seasonal movement. Many cod released in VIId were subsequently recaptured close to their release position, although some moved out of the Channel and into the southern North Sea. Overlap between the recapture areas of cod released in the different management areas was no more than 25% in either the spawning or feeding season. Behavioural data from electronic tags suggest that cod in IVc make use of tidal streams to migrate northwards and eastwards in spring, whereas selective tidal stream transport was rarely exhibited by cod tagged and released in VIId. Overall, the evidence suggests that there are behavioural differences between cod in IVc and VIId that limit the mixing of cod from these two areas during the feeding and spawning seasons.

Geomorphological and ecological characterization of a hard-substrate complex in a temperate shallow shelf sea (SE North Sea) using hydroacoustic sensors and machine learning algorithms

2020 ◽  
Author(s):  
Rune Michaelis ◽  
Lasse Sander ◽  
Finn Mielck ◽  
Svenja Papenmeier ◽  
H. Christian Hass
Keyword(s):  
Machine Learning ◽  
North Sea ◽  
Temporal Change ◽  
Learning Algorithms ◽  
Fine Sand ◽  
Machine Learning Algorithms ◽  
Hard Substrate ◽  
Sidescan Sonar ◽  
Substrate Complex ◽  
Hard Substrates

<p>The North Sea is a shallow marine environment. The sediment distribution of the seabed is dominated by sand-sized material. Hard-substrate areas are a relatively rare, but important habitat for sessile and mobile species. This habitat type forms island-like geomorphic features owing to the presence of glacial deposits in the shallow subsurface. While their ecological importance is widely acknowledged, hard-substrate areas are characterized by a large degree of spatial heterogeneity and an unaccounted high local diversity in physical surface properties, sediment composition and temporal change.</p><p>The aim of this study is the detailed investigation into the spatial characteristics and temporal variability of an exemplary hard-substrate complex located 10 km offshore the island of Sylt (N-Germany). The area has a size of c. 3 km<sup>2</sup>and was investigated between 2008 and 2019 using a range of hydroacoustic and optical sensors (multibeam echosounder, sidescan sonar, sub-bottom profiler, acoustic ground discrimination system, underwater videos) and machine learning algorithms (haar-like features) to track the changes in the number and local distribution of exposed stones.</p><p>The maximum water depth in the area is 16 m and a linear arrangement of hard substrates emerges up to 4 m from the seabed. A layer of fine sand with a thickness of 0.5 m overlays the more planarly deposited coarse sediments in the proximity of the stony outcrop. This layer of fine sand is relatively mobile and leads to a frequent temporal change of the distribution of sediment on the seabed, whilst the stony outcrop is only marginally affected by the spatial dislocation of sediments. The spatial extent of hard substrates is variable due to the presence of a mobile sand cover on the seabed.</p><p>This study emphasizes the need for quick and automated object classification routines to be integrated in monitoring approaches in the highly dynamic coastal zone. It has shown that the geomorphological diversity and interannual variability of hard-substrate areas can be captured using the presented approach. Detailed studies and monitoring tools are important to better understand the interrelation of geomorphological and sedimentary processes at the seabed with the ecology of epibenthic organisms.</p><p><strong>Keywords: </strong>North Sea; hard-substrate habitats; mobile sediments; hydroacoustic; haar-like features</p>

scholarly journals Direction Indication Lights

1969 ◽  
Vol 22 (2) ◽  
pp. 253-253
Author(s):  
H. V. Anguish
Keyword(s):  
North Sea ◽  
English Channel ◽  
Southern North Sea ◽  
Centre Line ◽  
Light Flashes

A Recent Admiralty Notice to Mariners (No. 1555/1968) advises that a vessel trading the southern North Sea and the English Channel has been fitted with experimental direction indication lights in order to indicate to an approaching vessel the direction in which she is altering course and the duration of the alteration. The positioning of these lights are 10·5 ft. higher than the after masthead light and 4 ft. outboard on each side of the centre line, and they are coloured red to port and green to starboard. When altering course the appropriate light flashes until the vessel is steadied up on her new course.

Winter zooplankton dynamics in the English Channel and southern North Sea: trends and drivers from 1991 to 2013

2021 ◽  
Author(s):  
Tim Dudeck ◽  
Norbert Rohlf ◽  
Christian Möllmann ◽  
Marc Hufnagl
Keyword(s):  
Chlorophyll A ◽  
North Sea ◽  
Environmental Drivers ◽  
Zooplankton Abundance ◽  
English Channel ◽  
Study Region ◽  
Chlorophyll A Concentration ◽  
Southern North Sea ◽  
Zooplankton Ecology ◽  
Zooplankton Size

Abstract Winter has long been regarded as a period of minor importance in marine zooplankton ecology with static, low concentrations and growth rates of organisms. Yet, there is growing evidence that winter conditions influence spring bloom strength. With rising water temperatures, growing importance of fish larvae survival during winter and the lack of data to parameterize ecosystem models for this period, research focus shifted on winter zooplankton ecology. To enable looking into past changes in winter zooplankton ecology, we established a new winter zooplankton time series based on samples collected in the eastern English Channel and southern North Sea by the International Herring Larvae Survey since 1988. Four areas of the study region were identified containing different congregations of zooplankton. Overall, zooplankton size decreased while total zooplankton abundance increased, reaching its maximum in 2011. Zooplankton abundance dynamics were mainly related to temperature, chlorophyll a concentration and North Atlantic Oscillation index. Depth and Atlantic water inflow strongly influenced zooplankton size. Increased chlorophyll a concentration and high abundances of small copepods indicated bottom-up controlled secondary production since 2010 and a possible winter bloom in 2011. Based on the analysed parameters, no relation between herring larvae abundance and zooplankton or environmental drivers was determined.

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