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1.
Habitat and Microhabitat of Mediterranean Clingfishes (Teleostei: Gobiesociformes: Gobiesocidae) 总被引：3，自引：0，他引：3
Abstract. This study addresses the habitat and microhabitat of the seven species of gobiesocid fish in the Mediterranean Sea. It is shown that Lepadogaster lepadogaster is closely adapted to large pebbles and boulder fields of rounded stones with a smooth surface. L. candollei is more euryecious and, in addition to inhabiting boulder fields also, occurs close to seagrass meadows, in small cavities and in association with sea urchins. Diplecogaster bimaculata is also euryecious and extends to greater depths. It lives on sand and muddy bottoms as well as on coralline grounds. At some locations this species is found in high abundance during the spawning season under empty bivalve shells or flat stones. Apletodon dentatus is the rarest species of Gobiesocidae in the Mediterranean Sea. It has a close association with seagrass or large brown algae ( Cystoseira ). Juveniles of A. incognitus are either associated with sea urchins or inhabit Posidonia meadows. Adults prefer the vicinity of seagrass meadows under empty bivalve shells and stones overgrown with red algae. Gouania wildenowi is stenoecious and is restricted to the interstices of roundish coarse gravel near the waterline. Opeatogenys gracilis is also stenoecious and lives only on the leaves of Posidonia and Cymodocea seagrass. The colourations of the different species and their variations are described and discussed. 相似文献
2.
Olof Lundberg 《Marine Policy》1984,8(4):337-346
Improving maritime communications is the raison d'être of INMARSAT, of which 40 countries are now members. INMARSAT operates the world's only commercial satellite system devoted to international mobile communications. This article describes the system and the services which can be provided through it, and covers the policy issues of interest to INMARSAT. It concludes by considering the future of maritime mobile communications via satellite. 相似文献
3.
Ocean Waves: Half-a-Century of Discovery 总被引：1，自引：0，他引：1
Paul H. LeBlond 《Journal of Oceanography》2002,58(1):3-9
While the nature of most ocean waves has long been known and their basic physics understood since the nineteenth century,
intense study of ocean waves during the second half of the twentieth century has taken the subject from the realm of mathematical
exercises to that of practical engineering. Modern understanding of the generation, propagation and interactions of ocean
waves with each other and with oceanic features has advanced to a quantitative level offering predictive capacity. This paper
presents a brief qualitative review of advances in knowledge of sound waves, wind waves, tsunamis, tides, internal waves and
long-period vorticity waves. The review is aimed at non-specialists who may benefit from an overview of the current state
of the subject and access to a bibliography of general-interest references.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
4.
Resource Management of Precious Corals: 总被引：6，自引：0，他引：6
Abstract. Precious corals as a group consist of a variety of species which belong to several classes of Anthozoan corals. In general, all are long lived, slow growing and are characterized by slow rates of annual recruitment and adult mortality. In favorable environments, where large beds of commercial quantity exist, their life history parameters often approximate steady state. In such instances, fishery management models in which the assumption of steady state is explicit, can be applied to their management. In this paper, the history and ecology of precious corals are reviewed in light of modern attempts of resource management using fishery models. In Hawaii, the BEVERTON and HOLT model has been adapted for the management of black, pink and gold coral species. The application of this model as it applies to precious corals is described and an example is given illustrating that it can also be used for shallow water reef building corals which form discrete colonies. 相似文献
5.
A wave-driven seawater pump, composed of a resonant and an exhaust duct joined by a variable-volume air compression chamber, is studied. The time dependent form of Bernoulli's equation, adapted to incorporate losses due to friction, vortex formation at the mouths and radiation damping, describes the pump behaviour. A dimensional analysis of the pump equations shows that a proposed scale-model will perform similar to a full-scale seawater pump. Fluid oscillations in the ducts perform similar to a damped, two-mass spring system, excited by the waves. A resonant condition can be maintained, for different wave frequencies, by varying the volume of air in the compression chamber. The dimensional analysis shows that the basic behaviour of the pump is linear and that its performance can be significantly increased by optimising the design of the duct mouths. Linear estimates of the resonant air chamber volume and flow rate through the pump are derived. 相似文献
6.
《Marine Policy》2005,29(3):223-234
In a previous paper on Canal management we examined the treaties and regulations underpinning firstly American and later Panamanian administration of the Canal. We also looked at the transfer of the Canal into Panamanian hands, including the management models used, ending with a review of toll structures and results. The subject of this paper is the operation of the Canal and the heated debate surrounding its modernisation, with a view to determining the adequacy of projected plans, as well as any future requirements, for maintaining its capacity in the 21 century. This paper seeks to analyse the Canal's operation, modernisation programmes and traffic systems as well as its key element: human resources. 相似文献
7.
Recognition of marine spiny lobsters of the Jasus lalandii group (Crustacea : Decapoda: Palinuridae)
All species of Jasus inhabit continental or island waters of the Southern Ocean. The are six species in the J. lalandii group which contains all but one of the known species of Jasus. Within the J. lalandii group two subgroups, each comprising three species, are recognised. Taxonomic variation is discussed and a key for identification presented. For efficient management, administrators should know the geographic limits of species on which fisheries are based. 相似文献
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Arnold H. Bouma 《Marine Geophysical Researches》1990,12(3):iii-vi
Editorial: Naming of undersea features 相似文献
10.
The motion of a deep-sea remotely operated vehicle system: Part 1: Motion observations 总被引：1，自引：0，他引：1
Rapid and high-resolution motion and tension measurements were made of a caged deep-sea remotely operated vehicle (ROV) system. Simultaneous measurements were made of all six components of motion at the cage and ship A-frame and of the tension in the tether at the ship. Data were collected for cage depths of 0–1765 m. The most significant forcing was in the wave-frequency band (0.1–0.25 Hz) and accounted for over 90% of the variance of vertical acceleration. The vertical acceleration of the cage lagged the acceleration of the A-frame by up to 1.9 s and its variance was larger by up to a factor 2.2. For moderate displacements of the A-frame (≤2 m), the system is only weakly non-linear because the harmonics (3rd and 5th) of the vertical acceleration of the cage account for less than 2% of the total variance. The system is essentially one-dimensional because only the vertical motion of the cage and the vertical motion of the A-frame were coherent, while horizontal motions of the cage were weak and incoherent with any component of motion of the A-frame. The natural frequency of the system is 0.22 Hz at 1730 m, and we estimate that it is within the waveband for depths between 1450 m and the full operating depth of 5000 m.Large vertical excursions of the A-frame produce momentary slack in the tether near the cage. Retensioning results in snap loads with vertical accelerations of 0.5 gravity. Large rates of change of tension and vertical acceleration first occur at the cage during its downward motion and propagate to the surface with the characteristic speed (3870 m s−1) of tensile waves for the tether. Six echoes are clearly detectable at both ends of the tether, and their pattern is extremely repeatable in different snap loads. Due to misalignment of the tether termination with the centres of mass and buoyancy, the cage pitches by up 14° during a snap. The resulting small radius of curvature poses the greatest stress on the tether. 相似文献
11.
C. L. Hopkins 《新西兰海洋与淡水研究杂志》2013,47(3):278-291
The systematics of the endemic New Zealand genus Paranephrops (Family Parastacidae) are re‐examined. Specific characters previously used to separate P. zealandicus and P. setosus are considered to be inadequate, and the two species are merged. The genus, as now proposed, contains only two species: P. planifrons, occupying the Whole of the North Island and northern and western areas of the South Island, and P. zealandicus, occupying eastern and southern parts of the South Island and Stewart Island. 相似文献
12.
《Deep Sea Research Part I: Oceanographic Research Papers》2000,47(5):789-824
The intermediate water masses in the eastern Atlantic Ocean between 31°N and 53°N were studied by analysis of the distributions of potential temperature, salinity, dissolved nutrients and oxygen. Sub-surface salinity minima are encountered everywhere in the area. At the northern and southern boundary they are connected with the presence of Sub-Arctic Intermediate Water and Antarctic Intermediate Water, respectively, but towards the European ocean margin the sub-surface salinity minima shift to shallower density levels. The sub-surface salinity minima observed west of the Iberian Peninsula represent a water mass formed by winter convection in the Porcupine Sea Bight and the northern Bay of Biscay. These minima gain salt by diapycnal mixing with the underlying Mediterranean Sea Outflow water and with the overlying permanent thermocline. The core of Antarctic Intermediate Water appears to contribute to the formation of Mediterranean Sea Outflow Water since it becomes entrained into the overflow near Gibraltar. This entrainment gives rise to an enhanced concentration of the nutrients in the Mediterranean water in the North Atlantic. The deep salinity minimum, due to the presence of Labrador Sea Water, is restricted mainly to the Porcupine Abyssal Plain. In the Bay of Biscay this water type is strongly modified by enhanced diapycnal mixing near the continental slope. At all intermediate levels the continental slope in the Bay of Biscay seems to be a focal point for water mass modification by diapycnal mixing. Below the core of the Mediterranean Sea Outflow Water the Labrador Sea Water is also strongly modified. Its salinity is strongly enhanced by diapycnal mixing with the overlying core of Mediterranean Sea Outflow Water. An analysis of the oxygen and nutrient data indicates that the large spatial concentration differences at the level of the Labrador Sea Water are caused mainly by ageing of the water. The youngest water is observed at 52°N, and, especially in the Bay of Biscay and off south-west Portugal, the water at levels of about 1700 dbar are strongly enriched in nutrients and depleted in oxygen. 相似文献
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J. A. Colman 《新西兰海洋与淡水研究杂志》2013,47(4):693-697
The unique holotype of Arnoglossus boops Hector is compared with specimens of Arnoglossus scapha (Schneider). It is concluded that the two species are identical, and that A. boops is therefore a junior synonym of A. scapha. 相似文献
15.
在我国南海海域大型底栖生物进行分类和多样性研究中,发现我国长眼寄居蟹属2个新记录种,紫斑长眼寄居蟹(Paguristes gonagrus)和条纹长眼寄居蟹(Paguristes runyanae),并对其进行描述。紫斑长眼寄居蟹采集自海南岛,主要特征为：螯足和步足密布刚毛,第一触角柄未达到角膜基部,螯足腕节、掌节背面刺和突起密集而发达,螯足和第二、三步足长节末端有紫色色斑;条纹长眼寄居蟹采集于西沙群岛,主要特征为：右螯足略大于左螯足,第一触角柄短,长度仅为眼柄长度的1/2,螯足和第二、三步足背腹面均有黄色条纹。 相似文献
16.
Regional co-development and security:: a comprehensive approach 总被引：1，自引：0，他引：1
Concepts of security are no longer limited to the military form, but other potential, economic, ecological, social aspects are becoming included.Emphasis needs to be put on integration of all dimensions of security. Many environmental problems present threats to human health and welfare and hence to the well-being of nations. The environmental issues cannot be ignored in context of any comprehensive security concept, but environmental security should not be treated in isolation.Integration of sustainable development and regional security may address many of the current maritime issues. Such integration may best be handled jointly and at regional levels.With this in mind and the realization that there is now a clear awareness and understanding that issues such as poverty, underdevelopment, population growth, environmental quality and sustainable resource use, are interrelated and interdependent and must be dealt with as such, the paper aims to highlight some aspects of regional security and sustainable development issues with reference to the Mediterranean basin. The aim is to initiate a process to pursue integration of sustainable development and comprehensive regional security with focus on the Mediterranean.The approach is based on the concept of the Common Heritage of Mankind as proposed by Arvid Pardo in 1967. It has 4 dimensions: economic; ethical; environmental; peace and security. In dealing with the proposal of Arvid Pardo the United Nations General Assembly decided to split up the concept: the Conference on the Law of the Sea was to deal with the peaceful uses of oceans and sea-beds; the Conference on Disarmament with the security aspects, then considered as military. UNCED 92 maintained the separation in addressing only environment and development, with management also included. However, peace and security were not included. It is time now to include these elements, and also consider the enforcement issue. The paper aims at illustrating this need through some examples from the Mediterranean basin. 相似文献
17.
1Introduction Benthic -pelagic coupling refers to the two -way exchange or flux of matter between benthic andpelagic environments in aquatic systems. Most stud-ies have focused on the deposition of non-living or-ganic matter to the seabed, resuspension an… 相似文献
18.
《Marine Policy》2014
This introduction explains the context and structure of a block of articles developed as part of the governance work packages of the FP7 project: “Options for Delivering Ecosystem-based Marine management” (ODEMM). 相似文献
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《Oceanic Engineering, IEEE Journal of》2001,26(1):26-53
A 1-km2 area located 2 km off the Florida Panhandle (30°22.6'N; 86°38.7'W) was selected as the site to conduct high-frequency acoustic seafloor penetration, sediment propagation, and bottom scattering experiments. Side scan, multibeam, and normal incidence chirp acoustic surveys as well as subsequent video surveys, diver observations, and vibra coring, indicate a uniform distribution of surficial and subbottom seafloor characteristics within the area. The site, in 18-19 m of water, is characterized by 1-2-m-thick fine-to-medium clean sand and meets the logistic and scientific requirements specified for the acoustic experiments. This paper provides a preliminary summary of the meteorological, oceanographic, and seafloor conditions found during the experiments and describes the important physical and biological processes that control the spatial distribution and temporal changes in these characteristics 相似文献