Spatial patterns and seasonality in the epibenthic communities of the Westerschelde (Southern Bight of the North Sea)

2000 ◽  
Vol 80 (1) ◽  
pp. 27-36 ◽  
Author(s):  
K. Hostens
Keyword(s):  
Longitudinal Axis ◽  
Common Species ◽  
Freshwater Species ◽  
Low Oxygen ◽  
Southern Bight ◽  
The North ◽  
Westerschelde Estuary ◽  
Large Numbers ◽  
Mesohaline Zone ◽  
Short Time

Beamtrawl samples were taken monthly between January 1988 and December 1989 in 14 subtidal stations along the longitudinal axis of the Westerschelde Estuary. The estuary harboured high densities of epibenthic species (total average of 2250 ind 1000 m−2). Only 37 fish species were recorded and three mobile macroinvertebrate species were quantified. Seventeen epibenthic species were common, only eight of which were very abundant. An overall dominance of the brown shrimp Crangon crangon was noted. The near absence of anadromous and freshwater species was correlated with the low oxygen concentrations upstream the Dutch–Belgian border. The epibenthic species could be divided into a polyhaline and a mesohaline community along the main salinity–oxygen–turbidity gradients of the estuary. The mesohaline zone was characterized by higher densities and biomasses for shrimps, gobies and flatfish. The spatial structure in the epibenthic community of the polyhaline zone was more influenced by the watermasses from the sea and inflowing channels, and was correlated with the degree of exposure (current velocities and tides). A classification is proposed, based on the season in which the epibenthic species occur in the estuary, and on their life stages and abundances during that period. The monthly data demonstrate that while the eight abundant epibenthic species were generally present throughout the year (summer or winter resident), the majority tended to appear in the Westerschelde at varying times (summer, winter or bimodal) and often remained in large numbers (nine common species) for only a short time. The fact that mainly juveniles were recorded in the higher density-classes, suggests that the Westerschelde Estuary still acts as a nursery area for many epibenthic species.

scholarly journals A PRELIMINARY NOTE ON THE INTERNAL PARASITES OF PUERTO RICAN CATTLE WITH SPECIAL REFERENCE TO THOSE SPECIES FOUND IN CALVES SUFFERING FROM "TROPICAL DIARRHEA"

1969 ◽  
Vol 24 (4) ◽  
pp. 121-132
Author(s):  
John S. Andrews ◽  
José F. Maldonado
Keyword(s):  
Puerto Rican ◽  
Intestinal Parasites ◽  
Common Species ◽  
Preliminary Note ◽  
Preliminary Step ◽  
The North ◽  
Large Numbers ◽  
Verminous Pneumonia ◽  
Internal Parasites ◽  
North And South

The results of a survey of the internal parasites of Puerto Rican cattle made as a preliminary step in connection with investigations on "tropical diarrhea" in calves have shown that the four most common species of gastro-intestinal parasites in the 22 calves autopsied were, B. phlebotomum (77.3%), O. radiatum (63.6%), C. punctata (54.5%), and H. contortus (50%). Eight of the 22 calves and one calf not autopsied were found to be suffering from "tropical diarrhea." These nine calves were from 2 to 11 months old and were about evenly divided between the central mountainous section and the north and south coastal plains. Eight of the nine cases occurred during the first 3 months of the calendar year. One occurred in June. E. zurni, together with the four species of nematodes just mentioned were recovered in large numbers from calves suffering from "tropical diarrhea.". The nematode, S. papillosus, was also implicated in one case as the result of finding large numbers of eggs in the feces of a calf. The remainder of the 21 species of parasites listed, with the exception of the lung worm, D. viviparus, which was found to be the cause of verminous pneumonia in 3 calves, were considered to be of little pathogenic importance in the calves examined.

Electronmicroscopic localization of ribonucleic acids in ciliate Bursaria truncatella during cell division

1990 ◽  
Vol 48 (3) ◽  
pp. 132-133
Author(s):  
Vladimir Popenko ◽  
Natalya Cherny ◽  
Maria Yakovleva
Keyword(s):  
Cell Division ◽  
High Specificity ◽  
Longitudinal Axis ◽  
Gold Complexes ◽  
Somatic Nucleus ◽  
Ribonucleic Acids ◽  
Biological Meaning ◽  
Bivalent Cations ◽  
Lowicryl K4m ◽  
Short Time

Highly polyploid somatic nucleus (macronucleus) of ciliate Bursaria truncatella under goes severe changes in morphology during cell division. At first, macronucleus (Ma) condences, diminishes in size and turns perpendicular to longitudinal axis of the cell. After short time, Ma turns again, elongates and only afterwards the process of division itself occurs. The biological meaning of these phenomena is not clear.Localization of RNA in the cells was performed on sections of ciliates B. truncatella, embedded in “Lowicryl K4M” at various stages: (1) before cell division (Figs. 2,3); (11) at the stage of macronucleus condensation; (111) during elongation of Ma (Fig.4); (1111) in young cells (0-5min. after division). For cytochemical labelling we used RNaseAcolloidal gold complexes (RNase-Au), which are known to bind to RNA containing cell ularstructures with high specificity. The influence of different parameters on the reliability and reproducibility of labelling was studied. In addition to the factors, discussed elsewhere, we found that the balance of mono- and bivalent cations is of great significance.

scholarly journals Controlling Shipping Along the North European Trade Axis

1971 ◽  
Vol 24 (4) ◽  
pp. 553-556
Author(s):  
D. J. Lindsay
Keyword(s):  
Weather Conditions ◽  
North Coast ◽  
Baltic Basin ◽  
Long Distance ◽  
The North ◽  
Large Numbers ◽  
Straight Line ◽  
European Trade ◽  
Trade Route ◽  
The Baltic

By the North European Trade Axis is meant the trade route from Ushant and Land's End, up the English Channel, through the Dover Strait fanning out to serve eastern England, the north coast of continental Europe and leading to the Baltic Basin. Recent events in this area have left a feeling that some form of tightening of control is not only desirable, but is rapidly becoming imperative. There is a basic conflict between the two forms of shipping using the area: the local users who use the area more or less constantly, and the long-distance traders, usually much larger, which arrive in the area for a brief stay after a prolonged period at sea, which has usually been in good weather conditions. Frequently these latter ships have a very poor notion of the hornet's nest into which they are steaming when they arrive. The net result is all too often the same: the local users, with familiarity breeding contempt, wander about as they see fit, with scant regard for routing or the regulations; all too often the big ships arrive from sea with navigating staffs who are too confused, sometimes too ignorant—and sometimes too terrified—to do much more than blunder forward in a straight line hoping for the best. Quite obviously this is not a total picture, and there are large numbers of ships which navigate perfectly competently, but the minority of those which do not seem to be rising rapidly, and show every sign of continuing to increase.

scholarly journals Haemoglobin polymorphisms affect the oxygen-binding properties in Atlantic cod populations

2008 ◽  
Vol 276 (1658) ◽  
pp. 833-841 ◽  
Author(s):  
Øivind Andersen ◽  
Ola Frang Wetten ◽  
Maria Cristina De Rosa ◽  
Carl Andre ◽  
Cristiana Carelli Alinovi ◽  
...  
Keyword(s):  
Evolutionary Biology ◽  
Quaternary Structure ◽  
Atlantic Cod ◽  
Three Dimensional ◽  
Oxygen Affinity ◽  
Oxygen Binding ◽  
Low Oxygen ◽  
Binding Properties ◽  
Important Species ◽  
The North

A major challenge in evolutionary biology is to identify the genes underlying adaptation. The oxygen-transporting haemoglobins directly link external conditions with metabolic needs and therefore represent a unique system for studying environmental effects on molecular evolution. We have discovered two haemoglobin polymorphisms in Atlantic cod populations inhabiting varying temperature and oxygen regimes in the North Atlantic. Three-dimensional modelling of the tetrameric haemoglobin structure demonstrated that the two amino acid replacements Met55β 1 Val and Lys62β 1 Ala are located at crucial positions of the α 1 β 1 subunit interface and haem pocket, respectively. The replacements are proposed to affect the oxygen-binding properties by modifying the haemoglobin quaternary structure and electrostatic feature. Intriguingly, the same molecular mechanism for facilitating oxygen binding is found in avian species adapted to high altitudes, illustrating convergent evolution in water- and air-breathing vertebrates to reduction in environmental oxygen availability. Cod populations inhabiting the cold Arctic waters and the low-oxygen Baltic Sea seem well adapted to these conditions by possessing the high oxygen affinity Val55–Ala62 haplotype, while the temperature-insensitive Met55–Lys62 haplotype predominates in the southern populations. The distinct distributions of the functionally different haemoglobin variants indicate that the present biogeography of this ecologically and economically important species might be seriously affected by global warming.

Field Implementation of RBI for Jacket Structures

2003 ◽  
Author(s):  
Michael H. Faber ◽  
Daniel Straub ◽  
John D. So̸rensen ◽  
Jesper Tychsen
Keyword(s):  
Sensitivity Analysis ◽  
Data Base ◽  
Stress Ratio ◽  
Oil And Gas ◽  
Inspection Planning ◽  
The North ◽  
Large Numbers ◽  
Structural Details ◽  
Jacket Structures ◽  
The North Sea

The present paper first gives a brief outline of the simplified and generic approach to reliability and risk based inspection planning and thereafter sets focus on a recent application of the methodology for planning of in-service NDT inspections of the fixed offshore steel jacket structures in the DUC concession area in the Danish part of the North-Sea. The platforms are operated by Maersk Oil and Gas on behalf of DUC partners A.P. Mo̸ller, Shell and Texaco. The study includes a sensitivity analysis performed for the identification of relevant generic parameters such as the bending to membrane stress ratio, the design fatigue life and the material thickness. Based on the results of the sensitivity analysis a significant number of inspection plans were computed for fixed generic parameters (pre-defined generic plans) and a data-base named iPlan was developed from which inspection plans may be obtained by interpolation between the pre-defined generic plans. The iPlan data-base facilitates the straightforward production of large numbers of inspection plans for structural details subject to fatigue deterioration. In the paper the application of the generic inspection plan database iPlan is finally illustrated on an example.

The Third Bosporus Bridge — the Aerodynamic Stability of the Steel Segments During the Lifting

2019 ◽  
Author(s):  
Vincent de Ville de Goyet ◽  
Yves Duchêne
Keyword(s):  
Vertical Axis ◽  
Longitudinal Axis ◽  
The Black Sea ◽  
Span Length ◽  
Geometrical Configuration ◽  
Aerodynamic Stability ◽  
The Third ◽  
The North ◽  
Torsional Instability ◽  
Main Cables

<p>The Third Bosporus Bridge is a suspendion bridge with a main span length of 1 408 m and a total length of 2 408 m located at the north of Istanbul near the Black Sea.</p><p>The main span is partially suspended at the pylons by stiffening cables and at the main cables with vertical hangers (Fig.1‐2). The deck is 58.8 m wide. But contrary to a classical arrangement, the transversal distance between the vertical hangers, in the suspended zone, is only 13.50 m. Due to this geometrical configuration of the vertical hangers, it was necessary to verify the risk of aeroelastic instabilities of steel segments of the deck during its lifting: risk of a torsional instability around the longitudinal axis but also around the vertical axis. Countermeasures have been proposed and adopted to suppress these risks.</p>

Structure of the chloroplast and its DNA in chloromonadophycean algae

1981 ◽  
Vol 49 (1) ◽  
pp. 401-409
Author(s):  
A.W. Coleman ◽  
P. Heywood
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Membrane ◽  
Nuclear Envelope ◽  
Chloroplast Dna ◽  
Single Layer ◽  
Longitudinal Axis ◽  
Chloroplast Envelope ◽  
Large Numbers ◽  
Gonyostomum Semen ◽  
Chloroplast Stroma

The arrangement and ultrastructure of chloroplasts is described for the Chloromonadophycean algae gonyostomum semen Diesing and Vacuolaria virescens Cienkowsky. The chloroplasts are present in large numbers and are discoid structures approximately 3–4 micrometer in length by 2–3 micrometer in width. In Gonyostomum semen the chloroplasts form a single layer immediately interior to the cell membrane; frequently their longitudinal axis parallels the longitudinal axis of the cell. The chloroplasts in Vacuolaria virescens are more than I layer deep and do not appear to be preferentially oriented. In both organisms, chloroplast bands usually consist of 3 apposed thylakoids, although fusion and interconnections between adjacent bands frequently occur. External to the girdle band (the outermost thylakoids) is the chloroplast envelope. This is bounded by endoplasmic reticulum but there is no immediately apparent continuity between this endoplasmic reticulum and the nuclear envelope. Electron-dense spheres in the chloroplast stroma are thought to be lipid food reserve. Ring-shaped electron-translucent regions in the chloroplast contain chloroplast DNA. The DNA is distributed along this ring in an uneven fashion and, when stained, resembles a string of beads. Each plastid has I ring, and the ring is unbroken in the intact plastid.

The Status of Coccinella septempunctata L. and its Varieties divaricata Oliv. and confusa Wied.

1962 ◽  
Vol 94 (12) ◽  
pp. 1341-1343 ◽  
Author(s):  
V. Sudha Rao
Keyword(s):  
Biological Control ◽  
Coccinella Septempunctata ◽  
Silver Fir ◽  
Eastern Himalayas ◽  
North West ◽  
The North ◽  
Large Numbers ◽  
The Status ◽  
Commonwealth Institute ◽  
Indian Station

A survey was recently undertaken by the author with Dr. V. P. Rao, Entomologist-in-charge, Indian Station, Commonwealth Institute of Biological Control, Bangalore, India, for natural enemies of Adelges spp. attacking silver fir (Abies spp.) and spruce (Picea spp.) in the North-West and Eastern Himalayas. In the course of this survey it was found that the coccinellids Coccinella septem-punctata L., C. septempunctata L. var. divaricata Oliv. and C. septempunctata L. var. confusa Wied, were three of the most common predators of Adelges spp. in both these areas. With a view to sending laboratory-reared material to Canada for trial against Adelges piceae Ratz., which is a serious pest there, large numbers of these Coccinellids were collected in the fir and spruce forests to provide breeding material.

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