用营养动态模式估算东海区大陆架渔场渔业资源蕴藏量

引用在东海区渔场进行的"海洋生物资源补充调查和资源评价"获得的初级生产力调查结果,综合已有的研究数据,采用PARSONS和CUSHING营养动态模式,对东海区渔场的渔业资源蕴藏量进行了估算。结果表明:1996～2005年东海区大陆架渔场渔业资源平均营养级为3.531级,近10年渔业资源年平均蕴藏量为836×104t,可捕量为418×104t左右;其中东海陆架渔场平均资源量为591×104t,可捕量296×104t;黄海南部平均资源量为245×104t,可捕量123×104t。2002～2005年东海区大陆架渔场平均资源蕴藏量为855×104t,可捕量为428×104t左右;东海区大陆架单位面积渔业资源蕴藏量为14.59t/km2,可捕量7.5t/km2;有机碳与鱼的比例为10.32:1,在世界各渔场中均属于较高水平;东海的单位面积渔业资源蕴藏量为8.89t/km2,东海区海域单位面积渔业资源蕴藏量为10.20t/km2,可捕量分别为4.5t/km2和5.1t/km2,高于黄渤海区和南海,略低于福建海区。目前东海区大陆架渔场的年渔获量已达750×104t左右,远远超过估算的420×104t左右年可捕量水平,使渔业资源始终处于过度捕捞状态。要使渔业资源恢复到良好状态,至少要减少目前40%的渔获量。     

Analysis of genetic variation within and among <Emphasis Type="Italic">Ulva pertusa</Emphasis> (Ulvaceae,Chlorophyta) populations using ISSR markers

Ulva pertusa is a native species to Asia along the western coast of Pacific Ocean,with new occurrence records in the eastern coast of Pacific,the northwest coast of Atlantic and the Mediterranean Sea.However,little is known about its population genetic structure.In this study,twelve U.pertusa populations from 3 coastal areas of China:Qingdao,Yantai and Dalian,were applied to ISSR analysis.The selected 4 ISSR primers amplified 120 polymorphic bands totally.Nei's gene diversity (H) ranged from 0.0729 to 0.149...     

模糊综合评价广西桂平东塔鱼类产卵场水质状况

依据2009年广西桂平市东塔鱼类产卵场水质调查监测结果,选择溶解氧(DO)、高锰酸盐指数(CODMn)、总氮(TN)、总磷(TP)4个代表性指标作为评价因子,参照《地表水环境质量标准(GB 3838-2002)》,应用模糊综合评价模型对该产卵场水质状况进行综合评价。结果表明,该产卵场水质为类,不符合天然鱼类产卵场水质要求;重点污染物是总氮。建议有关部门开展产卵场沿江污染源治理工作,加强产卵场水域环境的管理,进一步改善水质,修复产卵场水域环境,更好地保护鱼类生物多样性。     

基于鱼类产卵场保护的汛期生态流量阈值研究初探—以锦屏大河湾为例

以锦屏大河湾减水河段圆口铜鱼产卵场为例,采用IHARVA法分析了锦屏一级和二级电站运行对产卵场汛期流量过程等水文情势的改变及其对产卵的影响。在此基础上,以产卵适宜性条件为依据,选取减水河段中圆口铜鱼各产卵场代表特征断面,通过改进的R2-CROSS法确定了汛期生态基流量为298 m~3/s,并优化了水电站汛期调度方案,更有利于鱼类产卵场保护。     

Large contribution of sea surface warming to recent increase in Atlantic hurricane activity

Atlantic hurricane activity has increased significantly since 1995 (refs 1-4), but the underlying causes of this increase remain uncertain. It is widely thought that rising Atlantic sea surface temperatures have had a role in this, but the magnitude of this contribution is not known. Here we quantify this contribution for storms that formed in the tropical North Atlantic, Caribbean Sea and Gulf of Mexico; these regions together account for most of the hurricanes that make landfall in the United States. We show that a statistical model based on two environmental variables--local sea surface temperature and an atmospheric wind field--can replicate a large proportion of the variance in tropical Atlantic hurricane frequency and activity between 1965 and 2005. We then remove the influence of the atmospheric wind field to assess the contribution of sea surface temperature. Our results indicate that the sensitivity of tropical Atlantic hurricane activity to August-September sea surface temperature over the period we consider is such that a 0.5 degrees C increase in sea surface temperature is associated with a approximately 40% increase in hurricane frequency and activity. The results also indicate that local sea surface warming was responsible for approximately 40% of the increase in hurricane activity relative to the 1950-2000 average between 1996 and 2005. Our analysis does not identify whether warming induced by greenhouse gases contributed to the increase in hurricane activity, but the ability of climate models to reproduce the observed relationship between hurricanes and sea surface temperature will serve as a useful means of assessing whether they are likely to provide reliable projections of future changes in Atlantic hurricane activity.     

Directly measured mid-depth circulation in the northeastern North Atlantic Ocean

The circulation of water masses in the northeastern North Atlantic Ocean has a strong influence on global climate owing to the northward transport of warm subtropical water to high latitudes. But the ocean circulation at depths below the reach of satellite observations is difficult to measure, and only recently have comprehensive, direct observations of whole ocean basins been possible. Here we present quantitative maps of the absolute velocities at two levels in the northeastern North Atlantic as obtained from acoustically tracked floats. We find that most of the mean flow transported northward by the Gulf Stream system at the thermocline level (about 600 m depth) remains within the subpolar region, and only relatively little enters the Rockall trough or the Nordic seas. Contrary to previous work, our data indicate that warm, saline water from the Mediterranean Sea reaches the high latitudes through a combination of narrow slope currents and mixing processes. At both depths under investigation, currents cross the Mid-Atlantic Ridge preferentially over deep gaps in the ridge, demonstrating that sea-floor topography can constrain even upper-ocean circulation patterns.     

Influence of seasonal migration on geographic distribution of mitochondrial DNA haplotypes in humpback whales

Humpback whales (Megaptera novaeangliae) migrate nearly 10,000 km each year between summer feeding grounds in temperate or near-polar waters and winter breeding grounds in shallow tropical waters. Observations of marked individuals suggest that major oceanic populations of humpback whales are divided into a number of distinct seasonal subpopulations which are not separated by obvious geographic barriers. To test whether these observed patterns of distribution and migration are reflected in the genetic structure of populations, we looked for variation in the mitochondrial DNA of 84 individual humpback whales on different feeding and wintering grounds of the North Pacific and western North Atlantic oceans. On the basis of restriction-fragment analysis, we now report a marked segregation of mitochondrial DNA haplotypes among subpopulations as well as between the two oceans. We interpret this segregation to be the consequence of maternally directed fidelity to migratory destinations.     

Deep convection in the Irminger Sea forced by the Greenland tip jet

Open-ocean deep convection, one of the processes by which deep waters of the world's oceans are formed, is restricted to a small number of locations (for example, the Mediterranean and Labrador seas). Recently, the southwest Irminger Sea has been suggested as an additional location for open-ocean deep convection. The deep water formed in the Irminger Sea has the characteristic temperature and salinity of the water mass that fills the mid-depth North Atlantic Ocean, which had been believed to be formed entirely in the Labrador basin. Here we show that the most likely cause of the convection in the Irminger Sea is a low-level atmospheric jet known as the Greenland tip jet, which forms periodically in the lee of Cape Farewell, Greenland, and is associated with elevated heat flux and strong wind stress curl. Using a history of tip-jet events derived from meteorological land station data and a regional oceanic numerical model, we demonstrate that deep convection can occur in this region when the North Atlantic Oscillation Index is high, which is consistent with observations. This mechanism of convection in the Irminger Sea differs significantly from those known to operate in the Labrador and Mediterranean seas.     

Changes in fisheries discard rates and seabird communities

It is clear that discards from commercial fisheries are a key food resource for many seabird species around the world. But predicting the response of seabird communities to changes in discard rates is problematic and requires historical data to elucidate the confounding effects of other, more 'natural' ecological processes. In the North Sea, declining stocks, changes in technical measures, changes in population structure and the establishment of a recovery programme for cod (Gadus morhua) will alter the amount of fish discarded. This region also supports internationally important populations of seabirds, some of which feed extensively, but facultatively, on discards, in particular on undersized haddock (Melanogrammus aeglefinus) and whiting (Merlangius merlangus). Here we use long-term data sets from the northern North Sea to show that there is a direct link between discard availability and discard use by a generalist predator and scavenger--the great skua (Stercorarius skua). Reduced rates of discarding, particularly when coupled with reduced availability of small shoaling pelagic fish such as sandeel (Ammodytes marinus), result in an increase in predation by great skuas on other birds. This switching of prey by a facultative scavenger presents a potentially serious threat to some seabird communities.     

大眼金枪鱼资源利用状况分析

对世界大眼金枪鱼最近10年总渔获量以及太平洋、大西洋和印度洋的各渔区渔获量变化情况进行了统计分析；同时对大眼金枪鱼洄游分布，渔期变化及其海洋环境条件进行了论述；在此基础上，对今后合理利用、保护大眼金枪鱼资源在生产决策、渔场渔期选择以及加强对大眼金枪鱼中心渔场与海洋环境关系的科学研究方面提出了建议与措施。     

Reproductive failure in common seals feeding on fish from polluted coastal waters

The population of common seal Phoca vitulina in the westernmost part of the Wadden Sea, The Netherlands, has collapsed during the past few decades. Between 1950 and 1975 the population dropped from more than 3,000 to less than 500 animals. Comparative studies of common seal populations from different parts of the Wadden Sea reveal that pup production has declined sharply only in the western (Dutch) part. A comparative toxicological study on the levels of heavy metals and organochlorines in tissues of seals from the western and northern parts of the Wadden Sea shows that only the polychlorinated biphenyl (PCB) levels differ significantly. This is predominantly a result of PCB pollution from the river Rhine, which mainly affects the western (Dutch) part. PCBs are thought to be responsible for the low rate of reproduction in Dutch common seals on the basis of epidemiological and experimental data on the ability of PCBs to interfere with mammalian reproduction. Here I report that reproductive failure in common seals from the Dutch Wadden Sea is related to feeding on fish from that polluted area. This is the first demonstration of a causal relationship between naturally occurring levels of pollutants and a physiological response in marine mammals.     

Messinian salinity crisis regulated by competing tectonics and erosion at the Gibraltar arc

The Messinian salinity crisis (5.96 to 5.33 million years ago) was caused by reduced water inflow from the Atlantic Ocean to the Mediterranean Sea resulting in widespread salt precipitation and a decrease in Mediterranean sea level of about 1.5 kilometres due to evaporation. The reduced connectivity between the Atlantic and the Mediterranean at the time of the salinity crisis is thought to have resulted from tectonic uplift of the Gibraltar arc seaway and global sea-level changes, both of which control the inflow of water required to compensate for the hydrological deficit of the Mediterranean. However, the different timescales on which tectonic uplift and changes in sea level occur are difficult to reconcile with the long duration of the shallow connection between the Mediterranean and the Atlantic needed to explain the large amount of salt precipitated. Here we use numerical modelling to show that seaway erosion caused by the Atlantic inflow could sustain such a shallow connection between the Atlantic and the Mediterranean by counteracting tectonic uplift. The erosion and uplift rates required are consistent with previous mountain erosion studies, with the present altitude of marine sediments in the Gibraltar arc and with geodynamic models suggesting a lithospheric slab tear underneath the region. The moderate Mediterranean sea-level drawdown during the early stages of the Messinian salinity crisis can be explained by an uplift of a few millimetres per year counteracted by similar rates of erosion due to Atlantic inflow. Our findings suggest that the competition between uplift and erosion can result in harmonic coupling between erosion and the Mediterranean sea level, providing an alternative mechanism for the cyclicity observed in early salt precipitation deposits and calling into question previous ideas regarding the timing of the events that occurred during the Messinian salinity crisis.     

Continuous deep sea salt layer along North Atlantic margins related to early phase of rifting

Deep seismic reflexion surveys have revealed diapiric structures in deep water off Labrador, Newfoundland, Mauritania, Morocco, Portugal, Spain and Ireland as well as in the Mediterranean. Many of these diapirs are similar to the Gulf of Mexico salt domes, and it is suggested that there is a continuous deep sea salt layer, off the continental margin, which is related to the early phase of rifting.     

Deep roots of the Messinian salinity crisis

The Messinian salinity crisis--the desiccation of the Mediterranean Sea between 5.96 and 5.33 million years (Myr) ago--was one of the most dramatic events on Earth during the Cenozoic era. It resulted from the closure of marine gateways between the Atlantic Ocean and the Mediterranean Sea, the causes of which remain enigmatic. Here we use the age and composition of volcanic rocks to reconstruct the geodynamic evolution of the westernmost Mediterranean from the Middle Miocene epoch to the Pleistocene epoch (about 12.1-0.65 Myr ago). Our data show that a marked shift in the geochemistry of mantle-derived volcanic rocks, reflecting a change from subduction-related to intraplate-type volcanism, occurred between 6.3 and 4.8 Myr ago, largely synchronous with the Messinian salinity crisis. Using a thermomechanical model, we show that westward roll back of subducted Tethys oceanic lithosphere and associated asthenospheric upwelling provides a plausible mechanism for producing the shift in magma chemistry and the necessary uplift (approximately 1 km) along the African and Iberian continental margins to close the Miocene marine gateways, thereby causing the Messinian salinity crisis.     

热带海洋海表温度和西太平洋副高西伸脊点的关系研究

 应用谱分析的方法,讨论了热带太平洋、印度洋和大西洋海温对西太平洋副高西伸脊点的影响,得出热带太平洋、印度洋、大西洋海温变化对西伸脊点有影响的最佳落后时间长度.分别找出三大洋在上述落后时间长度下对西伸脊点东退和西伸有影响的关键区域.它可以作为西伸脊点东退或西伸的强信号因子,并对上述区域进行比较分析.西太平洋副高西伸脊点可以作为衡量东亚季风的一个指数,而东亚季风对处于低纬高原的云南的天气和气候有很大的影响.     

东海日本鳀数量分布和生物学特性的研究

根据2000～2002年在东海海域每年分季度4个航次双拖作业渔业资源调查和2000～2003年鳀鱼监测调查资料。对鳀鱼的数量分布和生物学特征进行了研究。结果表明，调查区鳀鱼的2000～2002年平均双拖网渔获率为0．55kg/h，以2000年冬季最高（2．06kg/h）且分布范围较广，2000秋季最低（0．0008kg/h）且极少有分布；鳀鱼在浙江近海的产卵期为2～5月，3月开始出现补充群体，经周年生长全长可达到约100mm。     

Mesozoic Alpine facies deposition as a result of past latitudinal plate motion

The fragmentation of Pangaea as a consequence of the opening of the Atlantic Ocean is documented in the Alpine-Mediterranean region by the onset of widespread pelagic sedimentation. Shallow-water sediments were replaced by mainly pelagic limestones in the Early Jurassic period, radiolarian cherts in the Middle-Late Jurassic period, and again pelagic limestones in the Late Jurassic-Cretaceous period. During initial extension, basin subsidence below the carbonate compensation depth (CCD) is thought to have triggered the transition from Early Jurassic limestones to Middle-Late Jurassic radiolarites. It has been proposed that the transition from radiolarites to limestones in the Late Jurassic period was due to an increase in calcareous nannoplankton abundance when the CCD was depressed below the ocean floor. But in modern oceans, sediments below the CCD are not necessarily radiolaritic. Here we present palaeomagnetic samples from the Jurassic-Cretaceous pelagic succession exposed in the Lombardian basin, Italy. On the basis of an analysis of our palaeolatitudinal data in a broader palaeogeographic context, we propose an alternative explanation for the above facies tripartition. We suggest that the Lombardian basin drifted initially towards, and subsequently away from, a near-equatorial upwelling zone of high biosiliceous productivity. Our tectonic model for the genesis of radiolarites adds an essential horizontal plate motion component to explanations involving only vertical variations of CCD relative to the ocean floor. It may explain the deposition of radiolarites throughout the Mediterranean and Middle Eastern region during the Jurassic period.     

Physiological and behavioural thermoregulation in bigeye tuna (Thunnus obesus).

Tuna are unique among teleost fishes in being thermoconserving. Vascular counter-current heat exchangers maintain body temperatures above ambient water temperature, thereby improving locomotor muscle efficiency, especially at burst speeds and when pursuing prey below the thermocline. Because tuna also occasionally swim rapidly in warm surface waters, it has been hypothesized that tuna thermoregulate to accommodate changing activity levels or ambient temperatures. But previous field experiments have been unable to demonstrate definitively short-latency, mammalian-type physiological thermoregulation. Here we show using telemetered data that free-ranging bigeye tuna (Thunnus obesus) can rapidly alter whole-body thermal conductivity by two orders of magnitude. The heat exchangers are disengaged to allow rapid warming as the tuna ascend from cold water into warmer surface waters, and are reactivated to conserve heat when they return into the depths. Combining physiological and behavioural thermoregulation expands the foraging space of bigeye tuna into otherwise prohibitively cold, deep water.     

东海区带鱼限额捕捞的初步研究

根据历年带鱼资源的调查和监测资料，运用数理模式和以往带鱼研究成果，计算了东海区带鱼的资源量、可捕量、最大持续渔获量，分析了资源状况，确定了东海区带鱼的总许可渔获量，探讨了东海区实行带鱼限额捕捞的可行性。     

Genetic diversity in Penaeus chinensis shrimp as revealed by RAPD technique

The random amplified polymorphic DNA analysis was used to estimate genetic diversity in one successively cultivated stock and three wild stocks of Penaeus chinensis shrimp, two of which were collected from the spawning and wintering grounds in the west coast of Korean Peninsula, and one from the feeding ground in the China coast of the Yellow Sea. A random primer kit was employed to scan the genomic DNA in 20 individuals of each index stock. A total of 110 reproducible RAPD markers were obtained, 68.2 % of which showed a sound eonformability within all the individuals detected, implying that the genetic variability in P. chinensis is relatively low. The proportions of polymorphic loci among these four stocks ranged from 20% to 33.3%, while the degrees of genetic polymorphisms varied from 0.0093 to 0.0307. The genetic variability of inter-stocks was higher than that of intra-stock. The genetic diversity in different stocks differed from each other; that is, a less genetic differentiation in the spawning and wintering stocks from the west coast of Korean Peninsula was revealed and their genetic diversities were higher than that of the spawning stock in the Bohai Sea and the China coast of the Yellow Sea. As detected, the genetic diversity in the successively cultivated stock was the lowest among these four stocks. Through genetic distance analysis between a random pair of individuals, a dendrogram of the above-mentioned four stocks was constructed by unweighted pair group method with arithmetic mean. The results based on cluster analysis well fitted with the geographical distribution of P. chinensis in the Bohai and Yellow Seas.