The Distribution of Hyas Araneus (L.) and Hyas Coarctatus Leach (Crustacea: Decapoda: Brachyura) in the North Sea and the Svalbard Region

1985 ◽  
Vol 65 (1) ◽  
pp. 195-201 ◽  
Author(s):  
M. F. Dyer
Keyword(s):  
Relative Density ◽  
North Sea ◽  
Benthic Invertebrates ◽  
Distribution Patterns ◽  
The North ◽  
The North Sea ◽  
Hyas Araneus ◽  
Presence And Absence ◽  
Marine Benthic Invertebrates

The distribution patterns of many marine benthic invertebrates are not well known, and when records exist they are usually in the form of presence and absence data with little or no information on the relative density of populations from area to area.

scholarly journals Spatial interactions between saithe (Pollachius virens) and hake (Merluccius merluccius) in the North Sea

2014 ◽  
Vol 71 (6) ◽  
pp. 1342-1355 ◽  
Author(s):  
Xochitl Cormon ◽  
Christophe Loots ◽  
Sandrine Vaz ◽  
Youen Vermard ◽  
Paul Marchal
Keyword(s):  
North Sea ◽  
Linear Models ◽  
Spatial Dynamics ◽  
Distribution Patterns ◽  
Trawl Survey ◽  
Spatial Interactions ◽  
Merluccius Merluccius ◽  
The North ◽  
Sediment Types ◽  
The North Sea

Spatial interactions between saithe (Pollachius virens) and hake (Merluccius merluccius) were investigated in the North Sea. Saithe is a well-established species in the North Sea, while occurrence of the less common hake has recently increased in the area. Spatial dynamics of these two species and their potential spatial interactions were explored using binomial generalized linear models (GLM) applied to the International Bottom Trawl Survey (IBTS) data from 1991 to 2012. Models included different types of variables: (i) abiotic variables including sediment types, temperature, and bathymetry; (ii) biotic variables including potential competitors and potential preys presence; and (iii) spatial variables. The models were reduced and used to predict and map probable habitats of saithe, hake but also, for the first time in the North Sea, the distribution of the spatial overlap between these two species. Changes in distribution patterns of these two species and of their overlap were also investigated by comparing species’ presence and overlap probabilities predicted over an early (1991–1996) and a late period (2007–2012). The results show an increase in the probability over time of the overlap between saithe and hake along with an expansion towards the southwest and Scottish waters. These shifts follow trends observed in temperature data and might be indirectly induced by climate changes. Saithe, hake, and their overlap are positively influenced by potential preys and/or competitors, which confirms spatial co-occurrence of the species concerned and leads to the questions of predator–prey relationships and competition. Finally, the present study provides robust predictions concerning the spatial distribution of saithe, hake, and of their overlap in the North Sea, which may be of interest for fishery managers.

Sea-level related molluscan plankton events (Gastropoda, Euthecosomata) during the Rupelian (Early Oligocene) of the North Sea Basin

2004 ◽  
Vol 83 (3) ◽  
pp. 199-208
Author(s):  
K. Gürs ◽  
A.W. Janssen
Keyword(s):  
Sea Level ◽  
North Sea ◽  
Temporal Distribution ◽  
Distribution Patterns ◽  
Short Term ◽  
The North ◽  
Early Oligocene ◽  
The North Sea

AbstractSpacio-temporal distribution patterns of North Sea Basin Early Oligocene (Rupelian) pteropoda (holoplanktonic gastropods: Mollusca, Gastropoda, Euthecosomata) are studied. These patterns indicate three short term invasions of a single pteropod species during the Rupelian. These invasions are indicated here as Clio blinkae Event, Praehyalocylis laxeannulata Event and Clio jacobae Event. The conspicuously short occurrences of the species, their abundances and some lithological features of the pteropod bearing strata lead to the conclusion that these plankton events are linked to sea level high-stands allowing currents from the worlds oceans to enter into the North Sea Basin.

scholarly journals Vertical distribution of pre-settled sandeel (Ammodytes marinus) in the North Sea in relation to size and environmental variables

2003 ◽  
Vol 60 (6) ◽  
pp. 1342-1351 ◽  
Author(s):  
Henrik Jensen ◽  
Peter J Wright ◽  
Peter Munk
Keyword(s):  
Vertical Distribution ◽  
Water Column ◽  
North Sea ◽  
Distribution Patterns ◽  
Food Concentration ◽  
The North ◽  
Vertical Distributions ◽  
The North Sea ◽  
Drift Trajectory ◽  
Vertical Positioning

Abstract Vertical distribution patterns of larval and juvenile sandeels were investigated at four locations in the North Sea. Sandeels between 6 and 65 mm were found to depths of 80 m, with vertical distributions dependent on both length and environmental factors. At one location with a stratified water column, the highest densities were found during the day in midwater where food concentration was also highest. In areas without marked vertical hydrographic gradients, larvae were relatively more abundant in surface waters during the day. At all locations, larvae of all sizes were generally more homogeneously distributed in the water column during night than during day. The extent of vertical migration, as measured by the standard deviation of the mean depth, increased generally with length. Gear avoidance was evident for larvae ≥20 mm. Catch efficiency generally depended on both length class and surface light intensity. A simulated drift pattern of larvae, based on ADCP current measurements from two locations, predicts that the horizontal drift trajectory would only be affected slightly by the vertical positioning of the larvae in the water column during the time of sampling. The implication of vertical migrations for dispersal of larvae away from the spawning grounds is discussed.

scholarly journals A sporomorph ecogroup model for the Northwest European Jurassic - Lower Cretaceous II : Application to an exploration well from the Dutch North Sea

2004 ◽  
Vol 83 (2) ◽  
pp. 81-91 ◽  
Author(s):  
O.A. Abbink ◽  
J.H.A. Van Konijnenburg-Van Cittert ◽  
C.J. Van der Zwan ◽  
H. Visscher
Keyword(s):  
Sea Level ◽  
North Sea ◽  
Distribution Patterns ◽  
Humid Climate ◽  
Depositional Sequence ◽  
Sea Level Fluctuations ◽  
The North ◽  
Reservoir Models ◽  
The North Sea ◽  
Central North Sea

AbstractJurassic shallow marine to non-marine depositional sequences are among the most important economic targets in the North Sea. Detailed, ‘high resolution’ stratigraphy of these sequences has become a necessity in both predictive geological exploration models as well as in production reservoir models. In these paralic sequences, palynomorphs are the most abundant (micro) fossil group. Palynology is increasingly challenged to improve the biostratigraphic control, and to support the sequence stratigraphical framework. Based on a recently developed, conceptual Sporomorph EcoGroup model, the quantitative distribution patterns of terrestrial palynomorphs are grouped in six Sporomorph EcoGroups (SEGs), viz. Upland, Lowland, River, Pioneer, Coastal, and Tidally-influenced SEG. Application of the SEG model to data from a marginal marine, uppermost Callovian - Middle Oxfordian section of NAM well F17-4 from the southern part of the Central North Sea Graben allows the recognition of sea-level fluctuations and climate changes. A marked palaeoclimatic shift occurred in the earliest Middle Oxfordian. The relatively cool-subtropical, humid climate changed into a warmer, subtropical-tropical, drier climate. The sea-level reconstructions based on the SEG model are validated against a latest Callovian - Earliest Oxfordian depositional sequence.

Benthic regions within the North Sea

1983 ◽  
Vol 63 (3) ◽  
pp. 683-693 ◽  
Author(s):  
M. F. Dyer ◽  
W. G. Fry ◽  
P. D. Fry ◽  
G. J. Cranmer
Keyword(s):  
North Sea ◽  
Benthic Invertebrates ◽  
The West ◽  
Classification Analysis ◽  
Faunal Assemblages ◽  
Southern North Sea ◽  
The North ◽  
Factors Influencing ◽  
The North Sea ◽  
Northern North Sea

During five annual ground fish surveys of the North Sea, all the benthic invertebrates trawled at 48 primary stations were recorded. The data were subjected to classification analysis, which showed a basic division between northern and southern North Sea benthos. The southern North Sea was further divided into three benthic regions, and the northern North Sea into four benthic regions (including one to the west of Shetland). The factors influencing the faunal assemblages in the various regions were discussed.

Geographic variation in the abundance and morphology of the bryozoan Alcyonidium diaphanum (Ctenostomata: Alcyonidiidae) in UK coastal waters

2002 ◽  
Vol 82 (4) ◽  
pp. 529-535 ◽  
Author(s):  
J.S. Porter ◽  
J.R. Ellis ◽  
P.J. Hayward ◽  
S.I. Rogers ◽  
R. Callaway
Keyword(s):  
North Sea ◽  
Coastal Waters ◽  
Additional Data ◽  
Distribution Patterns ◽  
Irish Sea ◽  
Southern North Sea ◽  
The North ◽  
The North Sea ◽  
Catch Rates ◽  
Trawl Catches

The ctenostome bryozoan Alcyonidium diaphanum is widespread and abundant in the coastal waters of England and Wales. It was recorded in 77–90% of beam trawl catches in the eastern English Channel and southern North Sea, and in 53–73% of catches in the Bristol Channel and Irish Sea. The maximum catch rates in these two study areas were 1410 and 751 kg h−1 respectively. Alcyonidium diaphanum was most abundant in the greater Thames Estuary. Additional data from the North Sea indicated that A. diaphanum is widely distributed throughout the southern North Sea. Alcyonidium diaphanum was found intertidally in only seven of 99 locations sampled. Several different morphotypes were observed, ranging from cylindrical to lobate forms. The distribution patterns of various morphotypes are discussed.

scholarly journals What controls the spatial distribution of the North Sea plaice spawning population? Confronting ecological hypotheses through a model selection framework

2009 ◽  
Vol 67 (2) ◽  
pp. 244-257 ◽  
Author(s):  
Christophe Loots ◽  
Sandrine Vaz ◽  
Benjamin Planque ◽  
Philippe Koubbi
Keyword(s):  
Spatial Distribution ◽  
Model Selection ◽  
North Sea ◽  
Survival Rates ◽  
Spatial Dynamics ◽  
Geographic Location ◽  
Distribution Patterns ◽  
The North ◽  
The North Sea ◽  
Selection Framework

Abstract Loots, C., Vaz, S., Planque, B., and Koubbi, P. 2010. What controls the spatial distribution of the North Sea plaice spawning population? Confronting ecological hypotheses through a model selection framework. – ICES Journal of Marine Science, 67: 244–257. The spatial dynamics of spawning fish are crucial because they influence the survival rates of eggs and larvae and ultimately impact the reproductive success of populations. The factors that control these dynamics are complex and potentially many, and they interact. A model-selection-based approach was developed to confront various hypotheses of control of the spatial distribution of spawning population of North Sea plaice (Pleuronectes platessa). For each hypothesis or combination thereof, statistical models were constructed. These were then ranked and selected based on their ability to adjust and predict observed spatial distributions. The North Sea plaice population seems to have developed strong attachment to specific spawning sites, where geographic location and population memory are important controlling factors. Temporal changes in spatial distribution patterns appear to be influenced primarily by population size and demography. Variations in hydrographic conditions such as temperature and salinity do not appear to control interannual fluctuations in spatial distribution. This means that, for reproduction, applying conventional habitat models may falsely attribute major controlling effects to environmental conditions. It is concluded that a multiple-hypothesis approach is essential to understanding and predicting the present and future distribution of the North Sea plaice population during its spawning season.

scholarly journals Using MPAs to address regional-scale ecological objectives in the North Sea: modelling the effects of fishing effort displacement

2009 ◽  
Vol 66 (1) ◽  
pp. 90-100 ◽  
Author(s):  
Simon P. R. Greenstreet ◽  
Helen M. Fraser ◽  
Gerjan J. Piet
Keyword(s):  
Species Diversity ◽  
North Sea ◽  
Benthic Invertebrates ◽  
Regional Scale ◽  
Fishing Effort ◽  
Fishing Mortality ◽  
Total Allowable Catch ◽  
The North ◽  
The North Sea ◽  
Ecological Objectives

Abstract Greenstreet, S. P. R., Fraser, H. M., and Piet, G. J. 2009. Using MPAs to address regional-scale ecological objectives in the North Sea: modelling the effects of fishing effort displacement. – ICES Journal of Marine Science, 66: 90–100. The use of Marine Protected Areas (MPAs) to address regional-scale objectives as part of an ecosystem approach to management in the North Sea is examined. Ensuring that displacement of fishing activity does not negate the ecological benefits gained from MPAs is a major concern. Two scenarios are considered: using MPAs to safeguard important areas for groundfish species diversity and using them to reduce fishing impacts on benthic invertebrates. Appropriate MPAs were identified using benthic invertebrate and fish abundance data. Fishing effort redistribution was modelled using international landings and fishing effort data. Closing 7.7% of the North Sea to protect groundfish species diversity increased the fishing impact on benthic invertebrates. Closing 7.3% of the North Sea specifically to protect benthic invertebrates reduced fishing mortality by just 1.7–3.8%, but when combined with appropriate reductions in total allowable catch (TAC), 16.2–17.4% reductions in fishing mortality were achieved. MPAs on their own are unlikely to achieve significant regional-scale ecosystem benefits, because local gains are largely negated by fishing effort displacement into the remainder of the North Sea. However, in combination with appropriate TAC reductions, the effectiveness of MPAs may be enhanced.

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