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Olafur S. Astthorsson Astthor Gislason Steingrimur Jonsson 《Deep Sea Research Part II: Topical Studies in Oceanography》2007,54(23-26):2456
This paper describes the main features of the Icelandic marine ecosystem and its response to climate variations during the 20th century. The physical oceanographic character and faunal composition in the southern and western parts of the Icelandic marine ecosystem are different from those in the northern and the eastern areas. The former areas are more or less continuously bathed by warm and saline Atlantic water while the latter are more variable and influenced by Atlantic, Arctic and even Polar water masses to different degrees. Mean annual primary production is higher in the Atlantic water than in the more variable waters north and east of Iceland, and higher closer to land than farther offshore. Similarly, zooplankton production is generally higher in the Atlantic water than in the waters north and east of Iceland. The main spawning grounds of most of the exploited fish stocks are in the Atlantic water south of the country while nursery grounds are off the north coast. In the recent years the total catch of fish and invertebrates has been in the range of 1.6–2.4 million ton. Capelin (Mallotus villosus) is the most important pelagic stock and cod (Gadus morhua) is by far the most important demersal fish stock. Whales are an important component of the Icelandic marine ecosystem, and Icelandic waters are an important habitat for some of the largest seabird populations in the Northeast Atlantic.In the waters to the north and east of Iceland, available information suggests the existence of a simple bottom-up controlled food chain from phytoplankton through Calanus, capelin and to cod. Less is known about the structure of the more complex southern part of the ecosystem. The Icelandic marine ecosystem is highly sensitive to climate variations as demonstrated by abundance and distribution changes of many species during the warm period in the 1930s, the cold period in the late 1960s and warming observed during the recent years. Some of these are highlighted in the paper. 相似文献
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Based on published estimates of areal extent, thickness and dating of igneous rocks related to formation of the North Atlantic
Volcanic Province, we calculate the magmatic production since the first reported magmatism at 70 Ma until present. We relate
the magmatism to the Icelandic Plume and estimate the total volumetric production to 22.1 × 106 km3. The magmatic production varied significantly with time, with a clear maximum of 55.5 m3/s around continental break-up at ca. 54 Ma. The lowest production is estimated at 4 m3/s, increasing to 7 m3/s at ca. 23 Ma. Two other pulses with increased activity are found around 40 Ma and in the late Miocene (10–5 Ma). The variations
in productivity are consistent with a plume pulsing with a periodicity of ca. 15 million years. The same periodicity and relative
timing is found for the Hawaiian Plume. If confirmed, these observations suggest that both plumes originate within the thin
boundary layer near the Core-Mantle Boundary. This hypothesis may imply periodic heating of the earth’s core with subsequent
heat-release to the mantle and increased global plume activity. 相似文献
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为了探索北大西洋涛动形成的大尺度大气物理场背景条件和外部强迫因子,通过对比分析、相关分析和环流系统温压场垂直结构分析得到:(1)强火山活动指数距平与冰岛低压和亚速尔高压海平面气压场(SLP)距平总体相关函数符号相反,强火山活动指数与冰岛低压SLP为反相关,与亚速尔高压SLP为正相关,就是说火山活动指数异常引起了高纬度冰岛低压和中低纬度亚速尔高压海平面气压场相反的变化趋势,形成高低纬之间海平面气压场反相振荡;(2)夏季7月亚速尔高压对流层中下层至海平面,温度距平中心和位势高度距平中心距平符号大致正正相对负负相对,说明夏季亚速尔高压为深厚暖性系统,低层温度升高亚速尔高压加强,低层温度降低亚速尔高压减弱,所以火山活动指数与亚速尔高压SLP均呈反相关关系;冬季1月对流层中下层至海平面,温度距平和位势高度距平符号大致正负相对,说明冬季亚速尔高压为浅薄系统,低层温度升高亚速尔高压减弱,低层温度降低亚速尔高压加强,所以火山活动指数与亚速尔高压SLP均呈正相关关系;(3)冬季1月冰岛低压对流层中下层至海平面,温度距平中心和位势高度距平中心距平符号大致正正相对负负相对,说明冬季冰岛低压为深厚冷性系统,低层温度升高冰岛低压减弱,低层温度降低冰岛低压加深,所以火山活动指数与冰岛低压SLP均呈反相关关系;夏季7月对流层中下层至海平面,温度距平和位势高度距平符号大致正负相对,说明夏季冰岛低压为浅薄系统,低层温度升高冰岛低压减弱,低层温度降低冰岛低压加深,所以火山活动指数与冰岛低压SLP均呈正相关关系;(4).由于对流层中下层至海平面冰岛低压和亚速尔高压冬、夏季温压场结构特点基本相反,火山活动指数异常在两个环流系统中引起了相反响应,导致高低纬之间海平面气压场反相振荡,形成了影响广泛的著名的北大西洋涛动现象。 相似文献
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Steingrímur Jnsson 《Progress in Oceanography》2007,73(3-4):231
The importance of the circulation of fresh water within the Nordic Seas has frequently been pointed out, especially its effect on deep water formation and therefore possibly on the thermohaline circulation. The main source of fresh water is the East Greenland Current entering the Nordic Seas through Fram Strait. The Jan Mayen Polar Current and the East Icelandic Current (EIC) carry a part of the fresh water into the Greenland and Iceland Seas respectively. As a part of the EU project VEINS, Aanderaa current meters were deployed on two moorings within the EIC from June 1997 to June 1998 on a standard CTD section from Langanes, Northeast Iceland, to the central Iceland Sea in the direction towards Jan Mayen. The current was mainly concentrated along the slope where it was baroclinic, while over the deeper part a weak barotropic flow was observed. Geostrophic calculations, referenced to the current meter data, were used for estimating the volume flux and fresh water transport with the current. The total transport over the section towards the east was found to be 2.5 Sv. The fresh water transport relative to a salinity of 34.93, above 170 m, amounted to 5.5 mSv. This is roughly 4% of the fresh water transport through Fram Strait. This transport is put into a long-term perspective using hydrographic data from the Langanes section. 相似文献
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《Marine Policy》2015
In this study, utilization of catch-quota balancing mechanisms in the Icelandic demersal fishery, which allow for individual transferable quota to be transformed among species and transferred between years, is analyzed to determine whether annual catches closely adhere to total allowable catches on average. Icelandic landings data for 14 demersal fish species during 2001–2013 are compared to implemented total allowable catches as well as catch limits recommended by the Marine Research Institute (MRI) and a proxy for annual market values. Landings surpassed legal limits of total allowable catch in 27% of the cases (landings by species by fishing year), mostly due to species transformations, but TAC overages were not consistent for any species. Instead, catches of some species were consistently less than legal limits, with some indications that landings were related to profitability (i.e. landings were correlated with market value). However, landings surpassed MRI recommendations in 67% of the cases, and landings of four species (Atlantic wolffish, haddock, monkfish and redfish) consistently exceeded MRI recommendations. Therefore, discrepancies between scientific recommendations for catch limits and quotas selected through the political process may represent a higher risk to long-term sustainability than catch-quota balancing mechanisms. 相似文献
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An attempt has been made to estimate the fishery potentials of the EEZ of India on the basis of data on primary and secondary production. The total column primary production and zooplankton production have been calculated to be 265·9 and 9 million tonnes of carbon per year, respectively. From these values the fishery potential has been estimated as 2·5 million tonnes per year. To this, if we add the estimated demersal fish catch, being 1·2 million tonnes per year, the total potential yield comes to 3·7 million tonnes per year. Since the present average total catch is about 1·6 million tonnes in a year, the fish catch could be doubled. 相似文献
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乐清湾水域纳潮量演变分析 总被引：2，自引：0，他引：2
基于1965年以来的不同时期水深地形数据和卫星遥感影像资料,对乐清湾岸线和不同特征值水深所围水域面积的历史变化进行研究,根据GIS技术计算乐清湾近50年的不同水域面积的演变特征。利用实测地形资料和水文数据建立乐清湾海域二维潮流数学模型分析乐清湾水域纳潮量的演变情况。结果表明:(1)乐清湾海域纳潮量近50年减少3.16×10~8 m~3,2013年较1965年减少17.69%,年均递减速率由0.06×10~8 m~3/a增加至近年的1.96×10~8 m~3/a;(2)海湾不同区域围填海造成相应海区水域面积的缩减,但纳潮量对水域面积改变的响应程度有显著差别。内湾滩涂围垦对乐清湾不同湾区纳潮量影响十分有限,外湾围垦对纳潮量的影响由外湾向内湾明显递减。漩门湾二期工程显著改变乐清湾的潮流形态,造成各个湾区纳潮量均出现大幅度的调整。本研究可以为海湾的生态环境保护和预测海湾的发展趋势提供量化的参考数据。 相似文献
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对墨西哥湾北部水深2200m的Alaminos Canyon645区块（AC645区）和水深540m的Green Canyon185区块（GC185区）冷泉碳酸盐岩的有机质进行了研究，结果显示深水和浅水区冷泉碳酸盐岩的有机质丰度和烷烃组成差别较大，下陆坡深水AC区样品有机质含量低，正构烷烃、萜烷、甾烷各组分的含量相对较高，正构烷烃以低碳数占绝对优势，并含有种类丰富的三环萜烷和五环三萜烷，且以17a（H），21B（H）-藿烷为主峰碳，反映了深水区冷泉碳酸盐岩的有机质来源于细菌和低等藻类，有少量的深部油气藏有机质的渗漏输入，并受微弱的微生物作用改造。上陆坡浅水GC区样品有机质含量较高，其中正构烷烃含量较低，并且以难以分开的复杂混合物（UCM）为主，同样含有种类丰富的以17α（H），21β（H）-降藿烷为主峰碳的三环萜烷和五环三萜烷，表明有机质主要来源于深部油气藏渗漏的有机质，并遭受了强烈的微生物降解。本文系统地研究了冷泉碳酸盐岩中正构烷烃、萜烷、甾烷的组成和分布特征，并探讨了有机质来源和冷泉渗漏的关系。 相似文献
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This article discusses the interaction of aniline and ocean algae based on the standard appraisal method of chemical medicine for algae toxicity. It is showed by experimental results that aniline has pretty toxic effects on algae. Suspended substances in water can offset some effects of aniline. It also discusses the dynamic constant of first order degradation reaction rate of algae on aniline from the point of view of chemical dynamics. 相似文献
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分析IP电话的国内外发展状况,探讨IP电话的发展趋势,研究中国政府及IP电话运营商应采用的应对策略,通过研究和分析,为IP电话下一步发展战略提供参考作用。 相似文献
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INTRODUCTIONThecontentsandtheirvariationofcellularbiochemicalcomponentsinnormallygrowingmarinealgaereflectthedifferenceinecologicalenvironments,reportedbymanyresearchers(MomsandSkea,1978;SmithandMoms,1980;LiandHarrison,1982;SmithandGeider,1985;Yangetal.,1991,1992).Lightintensity,temperatureandnutrientsaremostimPOrtantenvironmentalfactorsintheocean.ThispaperemphasizestheeffectsofenvironmentalfactorsonthecompositionofPhaendactylumtricornutum,Dunaliellaspp.,SkeletonemacostatumandIsOChr… 相似文献