Tidal currents at the North Hinder lightship, southern North Sea: Flow directions and turbulence in relation to maintenance of sand banks

1. Diameter measurements of Rhizosolenia styliformis from the Antarctic, the subtropical Atlantic and Pacific Oceans and from the North Sea and neighbouring waters have made it appear necessary to set up two varieties, oceanica and semispina, in addition to the type of the species R. styliformis. The type as I describe it has been called var. longispina by Hustedt, but elsewhere it has often been figured as the var. oceanica of this paper. Var. semispina is synonymous with the form represented by Karsten as R. semispina Hensen. It differs from R. semispina as drawn by Hensen and its synonym R. hebetata forma semispina Gran, but is thought likely to be linked by intermediates. If this is so R. hebetata may have to be extended to include and suppress R. styliformis, as var. semispina is linked to the type by intermediates. Var. oceanica has no intermediate forms and, if R. hebetata is to be extended, this variety should be established as a separate species.2. Var. oceanica is absent from the southern North Sea and appears to be an indicator species related to oceanic inflow.3. Auxospore formation was observed for the type in the southern North Sea in 1935 and biometric observations suggest that a period of 3-4 years elapsed between the production of auxospore generations in that area. Outside the southern North Sea for the type, measurements give no indication of auxospore generations occurring at intervals exceeding a year. While auxospore formation has been seen in var. oceanica from the Shetlands area samples of June 1935 and July 1938, this phenomenon has not been observed for var. semispina.

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The impact of sedimentary alkalinity release on the water column CO<sub>2</sub> system in the North Sea

Biogeosciences ◽

10.5194/bg-13-841-2016 ◽

2016 ◽

Vol 13 (3) ◽

pp. 841-863 ◽

Cited By ~ 19

Author(s):

H. Brenner ◽

U. Braeckman ◽

M. Le Guitton ◽

F. J. R. Meysman

Keyword(s):

Coastal Zone ◽

North Sea ◽

Dissolved Inorganic Carbon ◽

Co2 Uptake ◽

Overlying Water ◽

Southern North Sea ◽

The North ◽

Alkalinity Generation ◽

The North Sea ◽

The Impact

Abstract. It has been previously proposed that alkalinity release from sediments can play an important role in the carbonate dynamics on continental shelves, lowering the pCO2 of seawater and hence increasing the CO2 uptake from the atmosphere. To test this hypothesis, sedimentary alkalinity generation was quantified within cohesive and permeable sediments across the North Sea during two cruises in September 2011 (basin-wide) and June 2012 (Dutch coastal zone). Benthic fluxes of oxygen (O2), alkalinity (AT) and dissolved inorganic carbon (DIC) were determined using shipboard closed sediment incubations. Our results show that sediments can form an important source of alkalinity for the overlying water, particularly in the shallow southern North Sea, where high AT and DIC fluxes were recorded in near-shore sediments of the Belgian, Dutch and German coastal zone. In contrast, fluxes of AT and DIC are substantially lower in the deeper, seasonally stratified, northern part of the North Sea. Based on the data collected, we performed a model analysis to constrain the main pathways of alkalinity generation in the sediment, and to quantify how sedimentary alkalinity drives atmospheric CO2 uptake in the southern North Sea. Overall, our results show that sedimentary alkalinity generation should be regarded as a key component in the CO2 dynamics of shallow coastal systems.

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Marine Growth on North Sea Fixed Steel Platforms: Insights From the Decommissioning Industry

Volume 1A: Offshore Technology ◽

10.1115/omae2014-23352 ◽

2014 ◽

Author(s):

Chadi Mallat ◽

Alistair Corbett ◽

Glyn Harris ◽

Marc Lefranc

Keyword(s):

North Sea ◽

Gas Industry ◽

Southern North Sea ◽

The North ◽

The North Sea ◽

Insight Into

It is reputed in the Oil & Gas industry that marine growth is overestimated in the North Sea. Can we quantify this overestimation to better tackle the challenges marine growth incurs? This paper provides insight into the intrinsic and diverse nature of marine growth. It documents the biofouling development and the factors that affect it globally. Focus is made on fixed steel platforms in the North Sea approaching the end of their economic lives. A methodology to quantify the weight of marine growth is proposed and illustrated. 28 years after its installation, the weight of marine growth accumulated on Valhall 2/4G jacket located in Southern North Sea is evaluated based on the proposed method. It is confirmed that the current regulations overestimate the weight of marine growth in the North Sea.

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

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315400058410 ◽

1927 ◽

Vol 14 (3) ◽

pp. 685-721 ◽

Cited By ~ 9

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.

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Warm-water decapods and the trophic amplification of climate in the North Sea

Biology Letters ◽

10.1098/rsbl.2010.0394 ◽

2010 ◽

Vol 6 (6) ◽

pp. 773-776 ◽

Cited By ~ 15

Author(s):

J. A. Lindley ◽

G. Beaugrand ◽

C. Luczak ◽

J.-M. Dewarumez ◽

R. R. Kirby

Keyword(s):

North Sea ◽

Warm Water ◽

Climate Signal ◽

Southern North Sea ◽

The North ◽

Ecosystem Shift ◽

The North Sea ◽

Induced Changes ◽

Water Species

A long-term time series of plankton and benthic records in the North Sea indicates an increase in decapods and a decline in their prey species that include bivalves and flatfish recruits. Here, we show that in the southern North Sea the proportion of decapods to bivalves doubled following a temperature-driven, abrupt ecosystem shift during the 1980s. Analysis of decapod larvae in the plankton reveals a greater presence and spatial extent of warm-water species where the increase in decapods is greatest. These changes paralleled the arrival of new species such as the warm-water swimming crab Polybius henslowii now found in the southern North Sea. We suggest that climate-induced changes among North Sea decapods have played an important role in the trophic amplification of a climate signal and in the development of the new North Sea dynamic regime.

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The Carrack Field, Blocks 49/14b, 49/15a and 49/15b, UK North Sea

Geological Society London Memoirs ◽

10.1144/m52-2020-9 ◽

2020 ◽

Vol 52 (1) ◽

pp. 119-130 ◽

Cited By ~ 1

Author(s):

R. Rieu ◽

R. J. Porter

Keyword(s):

Production Rate ◽

North Sea ◽

The South ◽

Production Time ◽

Water Contact ◽

Southern North Sea ◽

The North ◽

Current Production ◽

Main Fault

AbstractThe Carrack Field, located in the Southern North Sea Blocks 49/14b and 49/15a, has of the order or 15 bcm (530 bcf) gas initially in place and is operated by Shell UK Ltd. The field consists of a pop-up structure in the south of the field and extends to the north with a gently-dipping monoclinal structure. The reservoir comprises sandstones of the Permian Silverpit and Leman Sandstone formations, which contain c. 85% of the in-place resources. The quality of the reservoir decreases rapidly to the north. Gas is also produced from Carboniferous sandstones of late Duckmantian (Westphalian B)–Bolsovian (Westphalian C) age.Initially, the field was in pressure communication both laterally and vertically with a single gas–water contact. During production time, however, the three main fault blocks behaved independently, and decimetre-thick shale intervals acted as vertical baffles between the sandstone units.The Carrack Field has been in production since 2003 and is developed by a single platform with seven mainly deviated wells. The current production rate is c. 0.7 MMm3/day (25 MMscfgd). Until the end of field life in the 2030s, the field is expected to produce gas of the order of a few bcm. The main remaining opportunity is the undeveloped Carrack West compartment.

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The Diversity of Nematode Communities in the Southern North Sea

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315400022189 ◽

1974 ◽

Vol 54 (1) ◽

pp. 251-255 ◽

Cited By ~ 36

Author(s):

C. Heip ◽

W. Decraemer

Keyword(s):

North Carolina ◽

North Sea ◽

Deep Sea ◽

Benthic Communities ◽

Nematode Communities ◽

Diversity Measure ◽

Southern North Sea ◽

The North ◽

Harpacticoid Copepods ◽

Logarithmic Series

Diversity is one of the most important parameters used in the description of a community; several theories relating diversity to other phenomena as predation, competition and stability have been proposed (Pianka, 1966). As a result of the increasing interest in diversity a number of studies have appeared during recent years, but the meiofauna has until recently been almost completely neglected, rather surprisingly when one considers the importance of this group of organisms in all marine benthic communities. Coull (1972) studied recently the diversity of harpacticoid copepods, with nematodes the major meiobenthic component, along the North Carolina shelf and in the deep sea. Warwick & Buchanan (1970) appear to be the only ones to have studied diversity in nematode communities, using α of the logarithmic series (Fisher, Corbett & Williams, 1943) as a diversity measure. The paucity of data seems primarily to be due to the taxonomic difficulties encountered in studying nematodes.

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

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315407054641 ◽

2007 ◽

Vol 87 (2) ◽

pp. 599-613 ◽

Cited By ~ 50

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.

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Shallow marine Lower and Middle Miocene deposits at the southern margin of the North Sea Basin (northern Belgium): dinoflagellate cyst biostratigraphy and depositional history

Geological Magazine ◽

10.1017/s0016756800004258 ◽

2000 ◽

Vol 137 (4) ◽

pp. 381-394 ◽

Cited By ~ 31

Author(s):

S. LOUWYE ◽

J. DE CONINCK ◽

J. VERNIERS

Keyword(s):

North Sea ◽

Depositional Environment ◽

Middle Miocene ◽

Depositional History ◽

Shallow Marine ◽

Dinoflagellate Cyst ◽

Southern North Sea ◽

The North ◽

Southern Margin ◽

The North Sea

Detailed dinoflagellate cyst analysis of the Lower–Middle Miocene Berchem Formation at the southernmost margin of the North Sea Basin (northern Belgium) allowed a precise biostratigraphical positioning and a reconstruction of the depositional history. The two lower members of the formation (Edegem Sands and decalcified Kiel Sands) are biostratigraphically regarded as one unit since no significant break within the dinocyst assemblages is observed. The base of this late (or latest) Aquitanian–Burdigalian unit coincides with sequence boundary Aq3/Bur1 as defined by Hardenbol and others, in work published in 1998. A hiatus at the Lower–Middle Miocene transition separates the upper member (the Antwerpen Sands) from the underlying member. The greater part of the Antwerpen Sands were deposited in a Langhian (latest Burdigalian?)–middle Serravallian interval. The base of this unit coincides with sequence boundary Bur5/Lan1. Biostratigraphical correlation points to a diachronous post-depositional decalcification within the formation since parts of the decalcified Kiel Sands can be correlated with parts of the calcareous fossil-bearing section, up to now interpreted as Antwerpen Sands. The dinoflagellate cyst assemblages are dominated by species with a inner neritic preference, although higher numbers of oceanic taxa in the upper part of the formation indicate incursions of oceanic watermasses into the confined depositional environment of the southern North Sea Basin.

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