Occurrence of hydromedusae in the plankton off Northumberland (western central North Sea) and the role of planktonic predators

1999 ◽  
Vol 79 (6) ◽  
pp. 979-992 ◽  
Author(s):  
K.R. Nicholas ◽  
C.L.J. Frid
Keyword(s):  
North Sea ◽  
East Coast ◽  
North East ◽  
The North ◽  
Pleurobrachia Pileus ◽  
Predatory Impact ◽  
Meganyctiphanes Norvegica ◽  
Central North Sea ◽  
Predation Rates

The pattern of occurrence of medusae off the north-east coast of England are described for the period 1990–1996. The predatory role of the medusae, Aglantha digitale, was examined by comparison of estimated predation rates with those of other planktonic predators. Aglanthe digitale was found to have the potential to considerably reduce copepod abundances, particularly in winter. Other important predators were the amphipod Themisto compressa and the chaetognath Sagitta elegans. There was a great deal of seasonal and interannual variability in predatory impact, with predators such as Pleurobrachia pileus and Meganyctiphanes norvegica occasionally exerting a high predatory impact. Previous studies have identified an important community structuring role for predation in winter in this area, this study shows that planktonic predators can influence copepod abundances throughout the year.

Seasonal Changes in Net Phytoplankton of the West-Central North Sea

1982 ◽  
Vol 62 (1) ◽  
pp. 15-23 ◽  
Author(s):  
J. W. Horwood ◽  
J. H. Nichols ◽  
Ruth Harrop
Keyword(s):  
Seasonal Changes ◽  
East Coast ◽  
Small Region ◽  
Zooplankton Biomass ◽  
The West ◽  
North East ◽  
The North ◽  
Central North Sea ◽  
Eggs And Larvae ◽  
Net Phytoplankton

INTRODUCTIONIn 1976 the Fisheries Laboratory, Lowestoft, carried out 13 plankton sampling cruises off the north-east coast of England. They spanned the months February-November. From these cruises Harding et al. (1978) described the distributions of surface chlorophyll and nutrients and the production offish eggs and larvae. Reynolds (1978) described in more detail the distributions of chlorophyll and phaeopigments throughout the year, and Horwood (1982) detailed the distribution of zooplankton biomass. This study presents the species composition of the algae from a small region of the survey area illustrated in Fig. 1.

Distribution, diversity and abundance of epibenthic fauna in the North Sea

1999 ◽  
Vol 79 (3) ◽  
pp. 385-399 ◽  
Author(s):  
Simon Jennings ◽  
John Lancaster ◽  
Andrew Woolmer ◽  
John Cotter
Keyword(s):  
North Sea ◽  
Temperature Difference ◽  
Free Living ◽  
North East ◽  
The North ◽  
The North Sea ◽  
Living Species ◽  
Northern North Sea ◽  
Epibenthic Fauna ◽  
Central North Sea

The assemblages of attached and freeliving epibenthic species in the North Sea are described, based on analysis of samples collected with a small beam trawl. Clustering of survey sites based on the presence or absence of attached species indicated that three regions had characteristic assemblages: the northern North Sea, the central North Sea from 55 to 57°N and the southern North Sea. Clustering of sites based on counts of free-living epibenthic species also revealed that the sites formed three major groups but these corresponded to regions in the north-east North Sea, the northern and western central North Sea and the southern and eastern central North Sea. Species which contributed most to the similarity within and dissimilarity between groups were identified. The environmental factors which best accounted for the grouping of sites were depth, winter temperature and the temperature difference between winter and summer for attached species and depth and the temperature difference between winter and summer for free-living species. The species richness of attached and free-living epibenthic species was higher in the central and northern North Sea than in the south. The number of abundant (Hill's N1) and very abundant (Hill's N2) free-living species also increased from south to north.

Changes in Western mackerel (Scomber scombrus) spawning stock composition during the spawning season

1986 ◽  
Vol 66 (2) ◽  
pp. 367-383 ◽  
Author(s):  
Wendy A. Dawson
Keyword(s):  
North Sea ◽  
Stock Assessment ◽  
East Atlantic ◽  
The West ◽  
Scomber Scombrus ◽  
North East ◽  
The North ◽  
Spawning Stock ◽  
The North Sea ◽  
Central North Sea

INTRODUCTIONTwo groups of mackerel (Scomber scombrus L.) are recognised by the International Council for the Exploration of the Sea (I.C.E.S.) for stock assessment purposes in the north-east Atlantic. The North Sea ‘stock’, which overwinters along the edge of the Norwegian Trench and spawns off the south coast of Norway, in the Skagerrak, Kattegat and the central North Sea (Hamre, 1980), and the Western ‘stock’, which overwinters and spawns along the edge of the continental shelf from the west of Ireland to the Bay of Biscay (Lockwood, Nichols & Dawson, 1981).

Ten Demi-Culverins for Aldeburgh: Whitehall, the Dunkirkers, and a Suffolk Fishing Community, 1625–1630

2019 ◽  
Vol 58 (2) ◽  
pp. 315-337 ◽  
Author(s):  
Thomas Cogswell
Keyword(s):  
North Sea ◽  
East Coast ◽  
Central Government ◽  
Fishing Community ◽  
Close Attention ◽  
The North ◽  
The North Sea ◽  
The Impact

AbstractHistorians have not paid close attention to the activities of freebooters operating out of Dunkirk in the late 1620s. This essay corrects that omission by first studying the threat from Dunkirk to England's east coast and then addressing how the central government, counties, and coastal towns responded. A surprisingly rich vein of manuscript material from Great Yarmouth and particularly from the Suffolk fishing community of Aldeburgh informs this case study of the impact of this conflict around the North Sea.

Exceptional influx of oceanic species into the North Sea late 1997

1999 ◽  
Vol 79 (4) ◽  
pp. 737-739 ◽  
Author(s):  
M. Edwards ◽  
A.W.G. John ◽  
H.G. Hunt ◽  
J.A. Lindley
Keyword(s):  
North Sea ◽  
Indicator Species ◽  
Climatic Conditions ◽  
Historical Evidence ◽  
East Atlantic ◽  
North East ◽  
The North ◽  
The North Sea ◽  
Oceanic Species

Continuous Plankton Recorder records from the North Sea and north-east Atlantic from September 1997 to March 1998 indicate an exceptional influx of oceanic indicator species into the North Sea. These inflow events, according to historical evidence, have only occurred sporadically during this century. This exceptional inflow and previous inflow events are discussed in relation to their similarity in terms of their physical and climatic conditions.

scholarly journals Ovary resorption in the Norway lobster (Nephrops norvegicus) and its possible causes with special reference to sperm storage

2020 ◽  
Vol 74 (1) ◽  
Author(s):  
Carola Becker ◽  
Jaimie T. A. Dick ◽  
E. Mánus Cunningham ◽  
Mathieu Lundy ◽  
Ewen Bell ◽  
...  
Keyword(s):  
North Sea ◽  
Demographic Data ◽  
Irish Sea ◽  
Natural Phenomenon ◽  
Nephrops Norvegicus ◽  
North East ◽  
The North ◽  
Norway Lobster ◽  
The North Sea ◽  
Reproductive Cycles

Abstract The Norway lobster, Nephrops norvegicus, is an important fisheries species in the North-East Atlantic area. In some circumstances, mature females of Nephrops norvegicus can resorb their ovary rather than completing spawning, but the implications of this phenomenon to reproductive biology and fisheries sustainability are not known. To understand after effects of ovary resorption, we studied long-term demographic data sets (1994–2017) collected from the western Irish Sea and the North Sea. Our considerations focused on potential correlations among the frequency of resorption, female insemination, and body size of resorbing females. Resorption was continuously rare in the western Irish Sea (less than 1%); whereas much higher rates with considerable year-to-year variation were observed in the North Sea (mean 9%). Resorption started in autumn after the spawning season (summer) had passed. The frequency stayed high throughout winter and declined again in spring. As sperm limitation can occur in male-biased fisheries, we expected a lack of insemination could be responsible for resorption, but affected females were indeed inseminated. Resorbing females were significantly larger than other sexually mature females in the North Sea, but the opposite trend was observed in the western Irish Sea. It is therefore possible that other, environmental factors or seasonal shifts, may trigger females to resorb their ovaries instead of spawning. Resorption may as well represent a natural phenomenon allowing flexibility in the periodicity of growth and reproduction. In this sense, observations of annual versus biennial reproductive cycles in different regions may be closely linked to the phenomenon of ovary resorption.

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