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1999年,我们已走到历史的十字路口:美国导弹袭击我驻南斯拉夫大使馆;日本从法律上正在打开通向军国主义的道路;台湾国民党当局已将李登辉“特殊的两国论”写入文件……现实告诉我们:当今的世界仍然是一个不稳定、动荡不安的世界。历史留给中国和平发展经济的 相似文献
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Salinity tolerance, energy metabolism, buoyancy, and passive sinking and swimming speeds have been studied for comparative assessment of the adaptive potential of two species of cyclopoid copepods in the Black Sea, the native Oithona similis and new invader Oithona davisae. Both species were considered marine euryhaline copepods, but the range of salinity tolerance of O. davisae was much broader (5–55‰). The energy metabolism, locomotor activity, mean body mass density, and speed of passive sinking at the same temperature were significantly higher in O. davisae than in O. similis. The relationship between the physiological and behavioral parameters and ecological characteristics of the species are discussed. 相似文献
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In the last few decades there has been a surge in research focusing on coral disease. While climate change, specifically rising sea surface temperature, has been proposed as a major and growing driver of the emergence of marine diseases, to date a solid connection between disease epizootics and elevated sea surface temperature has not been established. However, a wealth of data now exists, compiled from many different perspectives, that may support such a connection. In this work we provide a comprehensive review targeting one coral disease, black band disease, that spans the infection process, pathobiology, and epizootiology, and links specific mechanisms of the disease process to increasing temperatures. This temperature‐driven pattern of infection can be expanded to include similar processes associated with other temperature‐related coral diseases. The conclusions presented here are based upon the results of many studies using a diverse suite of approaches that have been synthesized to argue that the emergence and continuing spread of black band disease is linked to warming sea surface temperatures. In summary, as global ocean temperatures increase seasonally and over decades, the environment shifts to become more favorable for the growth of potentially pathogenic microorganisms endemic to the immediate environment of the reef. The increase in the relative number of potential pathogens in the microbial community produces microenvironments conducive to the growth of other potential pathogens, leading to infection by a polymicrobial consortium. This consortium is easily perturbed by a (seasonal) temperature decrease, but remains associated with the coral host and can be reactivated with a subsequent seasonal increase in temperature, resulting in a cycle of temperature‐dependent disease emergence. 相似文献
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Sayaka Yasunaka Yukihiro Nojiri Taketo Hashioka Chisato Yoshikawa Taketoshi Kodama Shin-ichiro Nakaoka Sanae Chiba Fuminori Hashihama Masahide Wakita Ken Furuya Daisuke Sasano Akihiko Murata Hiroshi Uchida Michio Aoyama 《Journal of Oceanography》2018,74(1):1-11
We used more than 25,000 nutrient samples to elucidate for the first time basin-scale distributions and seasonal changes of surface ammonium (NH4 +) and nitrite (NO2 ?) concentrations in the Pacific Ocean. The highest NH4 +, NO2 ?, and nitrate (NO3 ?) concentrations were observed north of 40°N, in the coastal upwelling region off the coast of Mexico, and in the Tasman Sea. NH4 + concentrations were elevated during May–October in the western subarctic North Pacific, May–December in the eastern subarctic North Pacific, and June–September in the subtropical South Pacific. NO2 ? concentrations were highest in winter in both hemispheres. The seasonal cycle of NH4 + was synchronous with NO2 ?, NO3 ?, and satellite chlorophyll a concentrations in the western subtropical South Pacific, whereas it was synchronous with chlorophyll-a but out of phase with NO2 ? and NO3 ? in the subarctic regions. 相似文献
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In this study, we exposed female medaka to aqueous solutions of o,p′-DDT until tissues residues reached approximately 100 g/g. Male offspring of exposed females and unexposed males that were raised to 6 months of age differed from untreated controls in their response to subsequent 4-day static exposure to 17-β-estradiol (E2; 12 μg/l as determined by steroid EIA). Homogenized liver samples from males from DDT treatments, females from DDT treatments, control males and control females produced two vitellogenin bands on a Western blot with no qualitative differences in band size and location between the groups. To quantify the relative level of vitellogenin, 5 μg of protein from each sample was analyzed by slot blot. A statistical comparison revealed a significant difference in optical density of the slots between control males and DDT exposed males (analysis of variance, n=18, P=0.021; Tukey test, n=9, P=0.047) indicating that previous transgenerational exposure to DDT enhanced the vitellogenic response to E2 exposure in males. These results indicate that exposure to estrogenic chemicals may produce an ‘estrogen memory’ which potentiates the response to a subsequent exposure event. 相似文献
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帆船运动场地及设施要素
帆船正式比赛的场地距海岸应有0．5～2千米，需要在开阔的水域上设4～5个比赛场地，每个场地直径约为1．9～3．6千米。这些区域水流不宜太大，水深不宜超过30米，不允许有固体漂浮物，渔网、渔排等障碍物。赛前及比赛期间这些场地区域对民用船及商业船只应当实行禁航。由海警在各区域外值守。 相似文献
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英国帆船Aera号船长杰斯·凡斯顿如是说：“每次面对帆船比赛，我都有一种爱恨交加的复杂心情，但我仍会不由自主地报名参加。因为骨子里那股拼搏超越的激情怂恿着我，更重要的是我热爱这项运动，无法割舍。” 相似文献
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帆船运动集合了娱乐性、观赏性、探险性、竞技性于一体。现代帆船运动更是各国人民进行航海文化交流的重要渠道．并且已经成为在世界沿海国家和地区最为普及且最受欢迎的体育活动之一。任何户外运动，基本安全常识都是必修课程，帆船运动当然也不例外，比起其他陆地运动，帆船运动所需要掌握的安全常识更加广泛。 相似文献
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Tatiana F. Maria Jan Vanaverbeke Ruth Gingold André M. Esteves Ann Vanreusel 《Marine Ecology》2013,34(2):207-217
Lately, across‐shore zonation has been found to be more important in structuring the nematode community of a tropical macrotidal sandy beach than microhabitat heterogeneity. To evaluate whether this zonation pattern applies to a temperate beach, a macrotidal ridge‐and‐runnels sandy beach in the North Sea was studied. We investigated whether a similar zonation occurs in sandbar and runnel microhabitats, and whether the runnels harbour a different community from the subtidal. Our results indicate that nematode communities from runnel and sandbar habitats are significantly different. In addition, horizontal zonation patterns for nematode communities differ between both habitats. Nematode assemblages from sandbars are divided to lower, middle and upper beach while upper and middle runnels cluster together. The subtidal and upper runnels showed dissimilar nematode assemblages, although runnels showed the same dominant species (Daptonema normandicum), which increases its abundance towards the upper runnels. This study illustrates the importance of microhabitat heterogeneity, which resulted in different zonation patterns across the sandy beach examined. The divergent zonation between sandbars and runnels in the macrotidal temperate sandy beach, compared with the pattern observed for a subtropical sandy beach with similar morphodynamics, indicates that generalizations about nematode distribution patterns should be made with caution. 相似文献
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The Commission on the Limits of the Continental Shelf has granted Australia extended continental shelf areas around two of its sub-Antarctic island groups, and these extend into the Antarctic Treaty area. The overlap potentially raises conflict between Australian and Antarctic interests. Australia's submission included and expressly excluded Antarctic data and its high-latitude diplomacy paid off, but its next steps will be crucial to gaining acceptance by other Antarctic Treaty parties. It is likely that any resource exploitation will stop at the fence (60° South) during the life of the Treaty. 相似文献
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Rosa Freitas Ana Maria Rodrigues Edward Morris Jose Lucas Perez-Llorens Victor Quintino 《Estuarine, Coastal and Shelf Science》2008,78(4):613-622
The single-beam acoustic ground discrimination system QTC View, Series V, was used in the Bay of Cadiz, Southwest Spain, for the identification and mapping of the bottom acoustic diversity. The acoustic data were obtained through two successive surveys, each conducted with one of the following echo sounder frequencies: 50 kHz and 200 kHz. The performance of each survey frequency for the identification of the sedimentary gradients was analyzed. The surveys were conducted during high tide given that the majority of the surveyed area is shallower than 5 m, although depth may occasionally reach 20 m in specific areas located in a navigation channel. The acoustic data obtained at the two different frequencies were, individually, submitted to manual clustering and a final solution consisting of three acoustic classes was reached for both datasets. However, only the geographical distribution of the acoustic classes obtained with 50 kHz echo sounder frequency was coincident with the spatial distribution of the superficial sediment groups (silty medium sand, very silty fine sand and mud), identified through multivariate analysis of the grain-size data of ground-truth sediment samples. The results obtained with the 200 kHz echo sounder frequency did not match the sedimentary gradients obtained for the area surveyed, not even the separation of muddy and sandy areas. 相似文献
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A. N. Gruzdev E. P. Kropotkina S. V. Solomonov A. S. Elokhov 《Izvestiya Atmospheric and Oceanic Physics》2017,53(2):195-203
Using results of ground-based spectrometric measurements, we analyze the anomalies in the stratospheric contents of O3 and NO2 in the Moscow region related to the sudden stratospheric warming and associated distortion of the stratospheric circumpolar vortex in early February 2010 and to the latitudinal displacement of the vortex towards the European sector in late March 2011 before the final spring warming. In the former case, the O3 concentration increased up to 85% and the stratospheric column NO2 content increased twice; in the latter case, the O3 concentration decreased by a quarter and the NO2 content decreased twice in comparison with average values for the time periods preceding the onsets of the anomalies. Estimates of the statistical correlationship of the stratospheric O3 and NO2 contents with potential vorticity and geopotential have been obtained. 相似文献
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Nineteen surface sediment samples, collected onboard ORV Sagar Kanya during the 199C and 200th (the pilot expedition to Southern Ocean) cruises along a north-south transect between 1.92° S to 55.01° S latitude and 67.88° E and 44.89° E longitude, were studied for total planktonic foraminiferal assemblage, relative abundance and the oxygen isotopic values of the indicator planktic species Globigerina bulloides. These profiles were compared with the latitudinal variations in the average salinity and nutrient (phosphate) contents of the top 100 meters water column. The initial results have traced the signatures of salinity linked variations of different water masses in the study region. The influence of Australian Mediterranean Water (AAMW) has been noticed in the present dataset. 相似文献
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This study investigated the sexual maturation process, release of spermatozoa or eggs and oocyte diameter of the rhizostomid medusae Nemopilema nomurai using samples collected from August 2006 to June 2008 from the waters around Korea and Japan, including peripheral areas outside the species’ usual habitat. Immature medusae were observed from June to October only in the western sector of the study area. The onset of spermatozoa and egg release occurred in September and October, respectively, and peaked in December and January. Medusae migrated eastward from source areas with the Tsushima Warm Current, where they formed gametes and spawned. Peak position and maximum oocyte diameter increased as the gonads developed according to the size-frequency distribution of oocytes. No fertilized eggs or embryos were found in the gonads. The correlation was analyzed with bell diameter, maximum oocyte diameter, sampling date, surface water temperature and gonad color to estimate which environmental factors and maturation indices were related to the maturation stage of females. Maturation stage correlated well with maximum oocyte diameter, which correlated negatively with surface water temperature. There was no significant correlation between bell diameter and maturation stage. Therefore, bell diameter was inappropriate for determining maturation index. Sex could not be distinguished clearly by gonad color. However, light pink gonads were more prevalent in males and various deep colors such as orange and brown were more frequent in female medusae. 相似文献
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