Host selection by larvae of a marine insect Halocladius variabilis: nutritional dependency or escape from predation?

2012 ◽  
Vol 93 (5) ◽  
pp. 1373-1379 ◽  
Author(s):  
Norah E. Brown ◽  
Sean C. Mitchell ◽  
David J. Garbary
Keyword(s):  
North Atlantic ◽  
Host Selection ◽  
Larval Growth ◽  
Petri Dish ◽  
Microhabitat Selection ◽  
The North ◽  
Significant Difference ◽  
Differential Behaviour ◽  
Algal Host ◽  
Marine Insect

Larvae of the Holarctic marine chironomid, Halocladius variabilis (Staeger), have strong fidelity to the tuft-forming brown alga, Elachista fucicola (Velley) Areschoug, an abundant epiphyte on intertidal fucoids of the North Atlantic. We show that larvae are sufficiently motile to select an algal host in a Petri dish within 3–4 cm, and that larvae show differential behaviour with respect to host selection in the presence or absence of a predator. In the absence of predators 53% of larvae found an algal host within 1 hour; however, after 24 hours, there was no significant difference in host selection. When an isopod predator (Idotea sp.) was present, more larvae found a host within 1 hour (81%) and Elachista was chosen over three of the four other hosts. Furthermore, when larvae were present in Elachista, predator (Carcinus maenus) success was significantly reduced relative to two other algal hosts. The adaptive significance of Elachista as a refuge from predation was confirmed by experiments demonstrating that larval growth with other algal hosts was greater than with Elachista. These experiments suggest that microhabitat selection by larvae of H. variabilis reveals important tradeoffs for growth and predator avoidance.

Subsidence of the Atlantic Moroccan margin during the Mesozoic

1998 ◽  
Vol 35 (4) ◽  
pp. 476-493 ◽  
Author(s):  
P Le Roy ◽  
F Guillocheau ◽  
A Piqué ◽  
A M Morabet
Keyword(s):  
Sequence Stratigraphy ◽  
North Atlantic ◽  
North Atlantic Region ◽  
Atlantic Region ◽  
The North ◽  
Essaouira Basin ◽  
High Resolution Analysis ◽  
Differential Behaviour ◽  
The North Atlantic ◽  
Well Correlation

This paper presents a combined study based on seismic interpretation, sequence stratigraphy, and the evaluation of subsidence that aims to characterize the structure and development of the Essaouira Basin in Morocco. Located in the coastal Meseta adjoining the continental margin, this basin records an initial Carnian-Hettangian deformation phase during rifting in the central part of the North Atlantic region. The geometry of the basin as a function of time shows a succession of half-grabens and horsts that developed westwards from reactivated Hercynian structures. The postrift stage is characterized by an aggrading sedimentary sequence, as shown by concordant seismic sequences stacking over the onshore part of the basin. The Upper Cretaceous coincides with a sequence showing a transition towards a prograding regime that leads to the topography of the present-day margin. Using the high-resolution analysis provided by sequence stratigraphy, it is possible to recognize fine-scale stratigraphic variations in the sedimentary succession. The well-to-well correlation of sedimentary cycles forms a dataset for evaluating subsidence. Residual subsidence curves reveal a differential behaviour between the present onshore and offshore areas. Although the computed subsidence rates are low across the onshore zone, curves for the western offshore part of the basin follow theoretical lithospheric cooling curves that are compatible with a stretch factor ( beta ) of nearly 1.4. Steep temporary gradients on the computed curves may be correlated with tectonic phases documented across the North Atlantic region that exerted a tight control on the development of the Essaouira Basin from Triassic rifting until the uplift of the Atlas Mountains during the Cenozoic.

scholarly journals The origin of glacial alpine landscape in Tröllaskagi Peninsula (North Iceland)

2016 ◽  
Vol 42 (2) ◽  
pp. 341 ◽  
Author(s):  
N. Andrés ◽  
L. M. Tanarro ◽  
J. M. Fernández ◽  
D. Palacios
Keyword(s):  
North Atlantic ◽  
Little Ice Age ◽  
Ice Age ◽  
Important Advance ◽  
North Central ◽  
The North ◽  
Significant Difference ◽  
Rock Glaciers ◽  
Basalt Plateau ◽  
Tertiary Basalt

The Tröllaskagi peninsula is located in north central Iceland, between meridians 19º30’W and 18º10’W , limited by Skagafjödur fiord to the west and the Eyjafjödur fiord to the east, jutting out into the North Atlantic to latitude 66º12’N and linked to the central Icelandic highlands to the south. The peninsula is a Tertiary basalt plateau topped by flat summits with altitudes of 1000-1500 m, intensely dissected by the drainage network. The aim of this present study is to synthesize the recent advances in our understanding of the landscape and its dynamics in the Tröllaskagi peninsula and find the origin of its significant difference from the rest of Iceland. Results of the most recent research suggest the situation of Tröllaskagi as ice-free, delimited by the two great glacial outlets flowing down from the Icelandic Ice Sheet through the Skagafjödur and Eyjafjödur fiords, from at least the Oldest Dryas to the end of the Early Preboreal. Inland in Tröllaskagi, the glaciers formed in the north-facing cirques without losing their alpine characteristics during the Late Pleistocene and Holocene. The advances of these glaciers during the Oldest, Older and Youngest Dryas and the Early Preboreal were only a few hundred metres greater than the most important advance in the second half of the Holocene, during the Little Ice Age. Only a few of these glaciers remained debris-free and are sensitive to the minor climate oscillations. The rest, due to the important geomorphological activity on their walls, developed into debris-covered and rock glaciers and lost this significant dynamism.

Estimation of Weibull distribution for wind speeds along ship routes

2016 ◽  
Vol 231 (2) ◽  
pp. 464-480 ◽  
Author(s):  
Wengang Mao ◽  
Igor Rychlik
Keyword(s):  
Wind Speed ◽  
Weibull Distribution ◽  
North Atlantic ◽  
Gaussian Model ◽  
Energy Harvest ◽  
Wind Speeds ◽  
The North ◽  
Significant Difference ◽  
The North Atlantic ◽  
Wind Distribution

In order to evaluate potential benefits of new green shipping concepts that utilize wind power as auxiliary propulsion in ships or of offshore wind energy harvest, it is essential to have reliable wind speed statistics. A new method to find parameters in the Weibull distribution is given. It can be used either at a fixed offshore position or along arbitrary ship routes. The method employs a spatio-temporal transformed Gaussian model for wind speed variability. The model was fitted to 10 years’ ERA-Interim reanalysis data of wind speed. The proposed method to derive Weibull distribution is validated using wind speeds measured on-board by vessels sailing in the North Atlantic and the west region of the Mediterranean Sea. For the westbound voyages in the North Atlantic, the proposed method gives a good approximation of the observed wind distribution along those ship routes. For the eastbound voyages, significant difference is found between the observed wind distribution and that approximated by the proposed method. The suspected reason is attributed to the ship routing decisions of masters and software. Hence, models that consider only the wind climate description need to be supplemented with a method to take into account the effect of wind-aware routing plan.

Navigation and Traffic Control over the North Atlantic

1957 ◽  
Vol 10 (2) ◽  
pp. 115-132
Author(s):  
D. O. Fraser
Keyword(s):  
North Atlantic ◽  
Traffic Control ◽  
Traffic Density ◽  
Aircraft Accidents ◽  
The North ◽  
Natural Tendency ◽  
Significant Difference ◽  
The North Atlantic ◽  
Wind Distribution ◽  
High Traffic Density

At present the total number of military and civil flights across the North Atlantic is about 130 per day counting both directions. Once aircraft are outside the systems of airways used in the high traffic density areas over each continent there are no fixed traffic lanes and aircraft plan their flights independently, generally following composite tracks to take maximum advantage of the wind distribution. Pilots are familiar with the natural tendency for tracks to diverge even when aircraft are being navigated via the same route but when the navigator in each aircraft is following an independent flight plan the separation of tracks will be much greater. Thus on the 2000-mile North Atlantic route the traffic density in real terms—say the number of aircraft per 10,000 square miles—is extremely low, and it is open to question whether the chance of two aircraft colliding in mid-Atlantic is not so remote as to be treated as an impossibility for practical purposes. This may sound heretical but if, as the writer suspects, the chance is so low as to make no significant difference to the overall risk of aircraft accidents, then there are other aspects of aircraft operation where the attention now being given to Atlantic traffic control might yield quicker dividends in the improvement of air safety.

The Currents of the North Atlantic

1892 ◽  
Vol 34 (872supp) ◽  
pp. 13940-13941
Author(s):  
Richard Beynon
Keyword(s):  
North Atlantic ◽  
The North ◽  
The North Atlantic

NATO adaptation to current challenges and mechanisms of Ukraine’s cooperation with the North Atlantic Treaty Organization

2019 ◽  
pp. 73-81
Author(s):  
Oleh Poshedin
Keyword(s):  
North Atlantic ◽  
Task Force ◽  
Response Force ◽  
Cyber Attack ◽  
Adaptation Measures ◽  
Joint Force ◽  
Security Environment ◽  
The North ◽  
The North Atlantic ◽  
Area Of Influence

The purpose of the article is to describe the changes NATO undergoing in response to the challenges of our time. Today NATO, as a key element of European and Euro-Atlantic security, is adapting to changes in the modern security environment by increasing its readiness and ability to respond to any threat. Adaptation measures include the components required to ensure that the Alliance can fully address the security challenges it might face. Responsiveness NATO Response Force enhanced by developing force packages that are able to move rapidly and respond to potential challenges and threats. As part of it, was established a Very High Readiness Joint Task Force, a new Allied joint force that deploy within a few days to respond to challenges that arise, particularly at the periphery of NATO’s territory. NATO emphasizes, that cyber defence is part of NATO’s core task of collective defence. A decision as to when a cyber attack would lead to the invocation of Article 5 would be taken by the North Atlantic Council on a case-by-case basis. Cooperation with NATO already contributes to the implementation of national security and defense in state policy. At the same time, taking into account that all decision-making in NATO based on consensus, Ukraine’s membership in the Alliance quite vague perspective. In such circumstances, in Ukraine you often can hear the idea of announcement of a neutral status. It is worth reminding that non-aligned status did not save Ukraine from Russian aggression. Neutral status will not accomplish it either. All talks about neutrality and the impossibility of Ukraine joining NATO are nothing but manipulations, as well as recognition of the Ukrainian territory as Russian Federation area of influence (this country seeks to sabotage the Euro-Atlantic movement of Ukraine). Think about it, Moldova’s Neutrality is enshrined in the country’s Constitution since 1994. However, this did not help Moldova to restore its territorial integrity and to force Russia to withdraw its troops and armaments from Transnistria.

Analysis of the ways of improvement of Ukraine – NATO cooperation on cybersecurity issues

2020 ◽  
Vol 10 (2) ◽  
pp. 11-15
Author(s):  
Volodymyr Shypovskyi ◽  
Volodymyr Cherneha ◽  
Serhiy Marchenkov
Keyword(s):  
Political Parties ◽  
North Atlantic ◽  
Lessons Learned ◽  
Cyber Warfare ◽  
The North ◽  
Collective Defense ◽  
Cyber Space ◽  
The Russian Federation ◽  
Modern Warfare ◽  
E Mail

Recent events in Ukraine have shown that, along with the advancement of information technology, methods of conducting modern warfare are being enhanced. Cyberspace is deliberately used by the Russian Federation to commit cyber warfare against Ukraine. Therefore, in order to address their influence effectively, it is important not only successfully deal with its consequences but also to foresee the potential adversaryʼs actions by analyzing their previous operations and incorporating the lessons learned by other countries. Across the globe, including Ukraine, the issue of information security and cyberattacks has become exceedingly urgent. Everybody is aware of the ongoing attacks on information networks of various government agencies and energy firms, cyberattacks on e-mail networks of political parties and organizations around the world. Likewise, despite the steadily growing numbers, cyberattack cases against the individuals and private businesses are not reported as widely as they occur. As a result, The North Atlantic Alliance countries began tackling the issue of cyberthreats much earlier than Ukraine. Consequently, NATO and its allies rely on powerful and robust cyber defenses to ensure the Alliance's core tasks of collective defense. The article discusses methods and strategies for providing cyber defense in NATO member states and recommends ways to increase the level of protection in the state's cyber space, as part of Ukraineʼs national security and defense domain.

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