Comparative fecundity of North Sea plaice ( Pleuronectes platessa L.)

1986 ◽  
Vol 228 (1253) ◽  
pp. 401-431 ◽  
Keyword(s):  
North Sea ◽  
German Bight ◽  
Relative Weight ◽  
Stage Iv ◽  
Analysis Of Covariance ◽  
Fish Length ◽  
English Channel ◽  
Southern Bight ◽  
The North ◽  
The Difference

Stage IV ovaries of plaice were obtained at sea from five spawning areas of the North Sea and English Channel (Eastern English Channel, Southern Bight, Central Southern North Sea, German Bight and Flamborough) in the years 1977, 1979 and 1980. Additional samples were provided from Dutch landings at IJmuiden for 1972. The numbers of eggs were counted from 790 fish. After a logarithmic transformation, analysis-of-covariance techniques were used to describe the relation between fecundity, given by the number of eggs, and fish length and age, and to examine fecundity differences between spawning area and year. After removing the effects of length and age, significant differences in fecundity were found between years. In the German Bight these were as much as 1.44 times. The data indicate that fecundities at a standard length and age were larger in 1980 than in 1979 but that the extent of the difference varied with spawning location. A gradual decrease in fecundity at a given length and age is shown from the eastern English Channel northwards to the German Bight. A significant decrease in fecundity with age, at a given length, is shown for all locations. Data from the Southern Bight and Flamborough were compared with those collected over the period 1947-9. The recent data from Flamborough show an increase in fecundity at length and age of 1.36 times and from the Southern Bight an increase of 1.6 times is found. The difference in the Southern Bight is reflected in the greater relative weight of the ovaries to body weight in 1980 compared with that in the 1940s. It is suggested that the modulation of fecundity could provide a potentially significant contribution to the natural regulation of the plaice population.

Origin of nitrogen in the English Channel and Southern Bight of the North Sea ecosystems

Hydrobiologia ◽  
2017 ◽  
Vol 845 (1) ◽  
pp. 13-33 ◽  
Author(s):  
Valérie Dulière ◽  
Nathalie Gypens ◽  
Christiane Lancelot ◽  
Patrick Luyten ◽  
Geneviève Lacroix
Keyword(s):  
North Sea ◽  
English Channel ◽  
Southern Bight ◽  
The North ◽  
The North Sea

Sole larval distribution (Solea solea) in the eastern English Channel and Southern Bight of the North Sea

2001 ◽  
Vol 81 (4) ◽  
pp. 673-678 ◽  
Author(s):  
A. Grioche ◽  
P. Koubbi ◽  
X. Harlay ◽  
B. Sautour
Keyword(s):  
North Sea ◽  
Environmental Parameters ◽  
English Channel ◽  
Southern Bight ◽  
Intermediate Variable ◽  
Larval Stages ◽  
The North ◽  
Larval Distribution ◽  
Solea Solea ◽  
The North Sea

The distribution of sole (Solea solea) eggs and larvae were described from two cruises conducted in April and May 1995 along the French coast of the eastern English Channel and the Belgian coast of the Southern Bight of the North Sea. Sole migration was investigated using larval stages and univariate spatial analysis as geostatistics (variograms). Important environmental parameters were selected by comparison with larval distribution. Path analysis was used to remove spatial correlation and to define links between abundance and environmental variables.  Sole larvae were found to be coastal throughout their development. Strong links between larval distribution and environmental parameters were identified, particularly for the younger stages which were found in higher abundance in areas of high chlorophyll-a concentration. The association was not direct, suggesting that the larval spatial distribution was influenced by an undetermined, intermediate variable, such as larval prey. Sole larvae are retained in the coastal area throughout ontogeny despite the strong hydrodynamics which characterize the region. Larval distribution resulted from behavioural mechanisms as well as environmental influences.

scholarly journals Long-term hydrological and phytoplankton monitoring (1992–2007) of three potentially eutrophic systems in the eastern English Channel and the Southern Bight of the North Sea

2011 ◽  
Vol 68 (10) ◽  
pp. 2029-2043 ◽  
Author(s):  
Alain Lefebvre ◽  
Natacha Guiselin ◽  
Frederique Barbet ◽  
Felipe L. Artigas
Keyword(s):  
North Sea ◽  
Inorganic Nitrogen ◽  
Regional Scale ◽  
Nutrient Concentrations ◽  
English Channel ◽  
Southern Bight ◽  
The North ◽  
The North Sea ◽  
Phytoplankton Monitoring

Abstract Lefebvre, A., Guiselin, N., Barbet, F., and Artigas, F. L. 2011. Long-term hydrological and phytoplankton monitoring (1992–2007) of three potentially eutrophic systems in the eastern English Channel and the Southern Bight of the North Sea. – ICES Journal of Marine Science, 68: 2029–2043. The spatial and main temporal variations in nutrient concentrations and phytoplankton abundance were investigated between 1992 and 2007 in the eastern English Channel and the Southern Bight of the North Sea, zones of consistent presence of Phaeocystis globosa and diatom blooms. Silicate and phosphate were the main nutrients potentially limiting phytoplankton growth, but the dynamics of the limitation seemingly differ between sites. Phosphate concentration showed a clear monotonic decreasing trend, whereas dissolved inorganic nitrogen and silicate trends were more complex. Nitrate was rarely or never a limiting factor. Results highlight three main periods with a Phaeocystis- or diatom-dominated system in the 1990s, and a more complex pattern in the 2000s. The composition of the phytoplanktonic community is described and an attempt made to establish a link between the community and its environment in terms of variability, shifts, and trends. The effects of larger- vs. regional-scale controlling factors are also discussed.

Macrobenthos of a Sublittoral Sandbank in the Southern Bight of the North Sea

1982 ◽  
Vol 62 (3) ◽  
pp. 521-534 ◽  
Author(s):  
C. Vanosmael ◽  
K. A. Willems ◽  
D. Claeys ◽  
M. Vincx ◽  
C. Heip
Keyword(s):  
North Sea ◽  
Tidal Currents ◽  
English Channel ◽  
Marine Transgression ◽  
Sea Floor ◽  
Southern Bight ◽  
Glacial Origin ◽  
The North ◽  
Belgian Coast ◽  
The North Sea

In the Southern Bight of the North Sea, off the Belgian coast, exists a series of parallel sublittoral sandbanks, the Flemish Banks, situated in a southwest-northeastern direction, 15–25 km long and 3–6 km wide. They are separated by channels, 4–6 km wide, and rise about 25 m above the surrounding sea-floor (Fig. 1). These sandbanks resulted from the accumulation of sandy deposits of glacial origin sedimented by the giant stream draining the waters from the present Rhine, Meuse, Scheldt and Thames before the Flandrian marine transgression about 12000 years ago. When from boreal times onwards the North Sea became slowly inundated, a connexion existed with the small English Channel which gradually enlarged, resulting in the very strong tidal currents which are responsible for the present geomorphology of the region.

The flow of water through the straits of Dover, related to wind and differences in sea level

1956 ◽  
Vol 248 (953) ◽  
pp. 517-551 ◽  
Keyword(s):  
Steady State ◽  
Sea Level ◽  
North Sea ◽  
Sea Water ◽  
Tidal Currents ◽  
English Channel ◽  
Mean Flow ◽  
North East ◽  
The North ◽  
The Difference

The difference in electric potential between the water on opposite sides of the English Channel, as recorded on a telephone cable running from St Margaret’s Bay to Sangatte, has been used to measure the mean flow of water through the Straits of Dover. The records were calibrated by means of the tidal currents, which were know from previous measurements. A p.d. of 1 V corresponds to a current of about 140 cm /s (2.75 knots), the exact calibration depending on the electrical conductivity o f the sea water and having a seasonal variation. Continuous records were obtained during the 15-month period from February 1953 to June 1954. For 4 months, from November 1953 to March 1954, similar records were also obtained on an other cable, crossing the southern North Sea from Aldeburgh to Domburg. Fluctuations due to the Earth currents associated with geomagnetic disturbances occurred from time to time, but did not usually cause any difficulty in in terpretin g the records. The residual flow, after eliminating the tidal currents, has been correlated with the local wind in the Straits and the difference in sea level between the eastern p a rt of the English Channel and the southern part of the North Sea, as determined from tide-gauge records. The tidal currents and elevations were eliminated, approximately, by taking means of 25 hourly readings centred at noon, for each day of the period covered by the observations. The greatest daily rates of flow recorded w ere 79 cm/s (T53 knots) towards the north-east on 1 November 1953 an d 77 cm /s (T49 knots) towards the south-w est on 3 January 1954. F or three periods of un usually strong flow, namely, 19 to 24 September 1953, 26 October to 8 November 1953, and 1 to 6 January 1954, a more detailed analysis was made, eliminating the tidal effects by a method previously used in the analysis of storm surges. The results show the existence of ‘current surges’, the peaks of which lag by up to 6 h behind the corresponding max im a in the wind stress or surface gradient producing them . An attempt has been made to relate the empirical results to the dynamics of flow through the Straits. On the assumption that the 25 h means can be regarded as referring to steady-state conditions, values o f 4-5 x 10<super>-3</super> for the w ind-stress coefficient y<super> 2</super> an d 3-8 x 10<super>-3</super> for the bottom friction coefficient k have been deduced. These rather high values may be due, in part, to the steady-state assumption not being justified. The general features of the current surges are consistent with the dynamical treatment.

Trend analysis of the published concentrations of heavy metals in aerosols above the North Sea and the English Channel for the period 1971-1994

1999 ◽  
Vol 7 (4) ◽  
pp. 191-202
Author(s):  
Stefaan Hoornaert ◽  
Boris Treiger ◽  
René Van Grieken ◽  
Remi Laane
Keyword(s):  
Heavy Metals ◽  
Trace Metals ◽  
Literature Review ◽  
Trend Analysis ◽  
North Sea ◽  
English Channel ◽  
Southern Bight ◽  
The North ◽  
The North Sea ◽  
Marine Areas

A literature review is given of atmospheric trace metal concentrations in aerosols above the North Sea and the English Channel over the period 1971-1994. Literature data have been gathered and intercompared to look for possible trends in the reported concentrations. Six trace metals are considered: Cd, Cu, Pb, Zn, Ni, and Cr. A distinction is made between measurements in different regions of the North Sea, and between coastal and marine areas. The majority of the data deals with the Southern Bight, providing the most reliable trends. Strong decreasing trends are observed for the Pb and Zn concentrations above the North Sea during the years 1971-1994. For Cd, Cu, Ni, and Cr, much less data are available in the literature. Despite this, also for Cd and Cu a decreasing trend is present. Cr and Ni concentrations are fluctuating, mostly without a certain pattern. The trends in the concentrations are also compared to changes in the European emission profiles. Key words: heavy metals, aerosols, North Sea, trend analysis, literature.

Mean Heat and Salt Budgets for the Eastern English Channel and Southern Bight of the North Sea

1982 ◽  
Vol 62 (3) ◽  
pp. 559-575 ◽  
Author(s):  
Linda Maddock ◽  
R. D. Pingree
Keyword(s):  
North Sea ◽  
Eddy Diffusion ◽  
English Channel ◽  
Southern Bight ◽  
The North ◽  
Temperature Distributions ◽  
Lack Of Information ◽  
Run Off ◽  
Salt Budget ◽  
The North Sea

In an earlier study Pingree, Pennycuick & Battin (1975) used a diffusion model to study the monthly temperature distribution and heat exchange in the English Channel. This showed that the diffusion would have to be adjusted according to the tidal ellipses for an improvement in the predicted temperature distributions, and that advection was probably an important factor at certain times of year. An attempt to use the same model for prediction of the salinity distributions was unsuccessful due partly to lack of information on run-off, precipitation and evaporation. The present study is an attempt to provide an overall monthly mean heat and salt budget for the eastern English Channel and Southern Bight of the North Sea which could serve as a preliminary to a two-dimensional mixing/advection model in which the horizontal eddy diffusion is represented as a tensor based on the tidal ellipse properties (Hunter, 1975).

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