排序方式： 共有50条查询结果，搜索用时 46 毫秒
31.
本文依据 1 989/ 1 990和 1 990 / 1 991南极夏季在普里兹湾邻近海域所获取的拖网样品 ,对大磷虾 (Euphausia superba Dana)的种群结构进行了分析。体长频数分布表明 ,种群中主要包括4个年龄组 ,即 1 + 、2 + 、3 + 、和 4+ 龄。 5 + 和 5龄以上的高龄组所含比重很小 (<3 %)。雌性临产个体 (3 DF)的体长频数分布表明 ,大磷虾的初次性成熟年龄为 3龄。生殖群体也以 3 +龄为主 ,4+龄次之。种群组成存在着明显的地区差异。普里兹湾以北海域是典型的双态分布 ,1 + 龄占有相当大比重 ;测区东西两侧以成体虾为主 ,极少有 1 + 龄虾。种群组成的年际变化也是明显的 ,特别表现在补充群体 (1 + 龄 )的强度上 相似文献
32.
Journal of Oceanology and Limnology - Coloration is an important phenotypic trait for multiple adaptive functions. It is interesting to find white-eye (AW) and orange-eye (AO) phenotypes in the... 相似文献
33.
北极深海沉积物中细菌和古菌群落结构研究 总被引：3，自引：0，他引：3
在北极深海沉积物生态系统中,微生物的群落结构由有机质输入、能量的可用性及其他环境因素决定.然而,全球气候变暖及其导致的冰盖提前融化正在影响微生物的多样性.为描述北极深海沉积物中的微生物群落结构及其与环境因素的相关性,我们利用罗氏454对北极深海沉积物样品的16S rDNA扩增子进行了测序,对细菌和古菌群落的丰富度、成分、结构及其系统发育分类地位进行了描述.硫还原和化能有机营养类是细菌群落中的主要类群;而古细菌群落主要是由微生物的关系最为密切的氨氧化奇古菌门(96.66%)和产甲烷古生菌界(3.21%).这项研究描述了北极极点附近深海沉积物(> 3500米)中的微生物多样性,将为以后研究类似环境中微生物代谢过程和途径等功能分析奠定基础. 相似文献
34.
The information of trophic relationship is important for studying the Southern Ocean ecosystems. In this study, three dominant krill species, Euphausia superba, Thysanoessa macrura and Euphausia crystallorophias, were collected from Prydz Bay, Antarctica, during austral summer of 2009/2010. The composition of fatty acids in these species was studied. E. superba and T. macrura showed a similar fatty acid composition which was dominated by C14:0, C16:0, EPA (eicosapentenoic acid) and DHA (decosahexenoic acid) while E. crystallorophias showed higher contents of C18:1(n-9), C18:1(n-7), DHA and EPA than the former two. Higher fatty acid ratios of C18:1(n-9)/18:1(n-7), PUFA (polyunsaturated fatty acid)/SFA (saturated fatty acid), and 18PUFA/16PUFA indicated that E. crystallorophias should be classified as a typical omnivore with a higher trophic position compared with E. superba and T. macrura. 相似文献
35.
强壮箭虫是我国温带海域的浮游动物优势种。本文通过2009年7月至2010年6月在北黄海獐子岛海域的逐月综合调查,研究了大网浮游动物中强壮箭虫丰度的周年变化及其与环境因子的关系。结果显示,强壮箭虫年平均丰度为22.6 ind/m3,高峰值出现在12月（47.5 ind/m3）,最低值出现在8月（7.8 ind/m3）;在水平分布上,除了夏季的8月,全年近岸海域强壮箭虫丰度均高于外海海域,且在10月及次年2月差异显著（P<0.05）。相关性分析显示,作为肉食性浮游动物,强壮箭虫丰度时空变化除了受温度和盐度影响外,还与饵料生物（主要是桡足类）丰度有关。我们认为,这是其丰度周年变化规律在不同海域出现明显差异的主要原因。 相似文献
36.
Wang Pengpeng Zhang Fang Sun Song Wang Weicheng Wan Aiyong Li Chaolun 《中国海洋湖沼学报》2020,38(4):1256-1269
The population explosion of jellyfish Aurelia coerulea occurred in Jiaozhou Bay,China in 2009.The potential predation impact of A.coerulea on zooplankton was investigated.Population clearance potential and residence time(t_(1/2)) for copepods were calculated from laboratory clearance rates and measurements of jellyfish size and abundance from May to August 2009 in Jiaozhou Bay.Clearance rates varied widely with prey organisms,but they were not significantly different among various prey concentrations.Medusae captured rotifers,fish larvae and hydromedusae more efficiently than fish eggs,copepods and chaetognaths.Ephyrae captured rotifers and hydromedusae more efficiently than fish larvae and copepods.Clearance rate linearly increased with the cro s s sectional area of A.coerulea(size from 0.3 to7.1 cm).Water temperature also had a marked effect on clearance rate and this was related to the increased beat freque ncy as water temperature increased.In early May 2009,A.coerulea potentially cleared the volume of water in the Bay less than 0.001 times a day,but this value was estimated to be more than 0.3 times a day in July.The t_(1/2) for copepods was less than 6 d in June and July.Abundances of copepods,hydromedusae and chaetognaths were extremely low in 2009 compared to 2008 and 2010(jellyfish non-bloom years).Large predation pressure by the A.coerulea population occurred to control zooplankton communities in Jiaozhou Bay.A.coerulea,when present at a high population level,can be a keystone species in Jiaozhou Bay and control the trophic structure here. 相似文献
37.
胶州湾的初级生产力和新生产力 总被引：2，自引：0，他引：2
海洋初级生产力是海洋食物链的基础,是进行海洋生物资源评估和合理开发利用的基本依据。70年代在国际生物圈计刘(IBP)的推动下,本领域的一些学者曾在世界各大洋的代表性海区进行过大量现场观测研究。最近,随着世界性的资源与环境问題的日趋严重,全球C循环已成为人们关注的研究课题。海洋初级生产力是了解全球C循环必不可少的指标之一,因而再度成为生物海洋学家的研究对象。新生产力是总初级生产力的一部分,亦是海洋N循环的特征参数,对于大洋水域而言,它反映了真光层生物群落的净生产力,代表了真光层向下输出的C通量,是当今有关国际研究计划,如全球海洋通量联合研究( JGOFS)的核心内容之一。初级生产力和新生产力的研究,对于海洋生物资源的持续利用和C、N生物地球化学循环具有十分重要的意义。
胶州湾作为我国温带地区的典型海湾,已成为我国生态研究系统网络(CERN)的野外观测站。代表性的地理位置和强度开发下的生态条件,使其生态学资料在环境监测和资源开发方面极具理论意义和应用价值。胶州湾的初级生产力曾用黑白瓶生氧量法测定过(郭玉洁等,1992),而新生产力的实测研究在国内尚属空白。本文运用14C,15N同位素示踪方法,在胶州湾进行了季节性的初级生产力和新生产力现场实验研究,获得了比较系统的观测资料。 相似文献
38.
极地海区浮游动物对全球气候变化的响应极其敏感,其群落结构已成为研究全球变化对海洋生态系统影响的重要指标,而DNA条形码则是浮游动物种类鉴定的有效工具。采用线粒体细胞色素c氧化酶第一亚基编码基因(mtCOI)特异扩增测序的方法,分析了南大洋32种常见浮游动物的94条DNA条形码序列,其长度分布在830碱基到1050碱基之间。发现南极常见浮游动物种内遗传差异均值为0.67%,分布在0—2.6%之间;同属近源种间遗传差异均值为14.3%,分布在0.1%—29.3%之间。哲水蚤属的近缘哲水蚤(Calanus propinquus)和C.simillimus遗传相似度非常高。考虑到上述两者在形态和遗传上的相似性,本研究认为两种可能为同种异名,有待开展深入研究确认C.simillimus种的地位。除了哲水蚤属的两种外,所有样品种内、种间遗传差异显著,且同种的不同样品都聚到一起形成单系群。结果表明mtCOI序列可以作为DNA条形码实现南极浮游动物常见种的准确鉴定(水母和海樽等胶质浮游动物的有效性未验证)。以上结果也得到了示踪向量分析的证实。本研究新增的DNA条形码数据以及新提供的兼并引物必将推动南极浮游动物环境样品的宏基因组学研究。 相似文献
39.
Calanus sinicus is a calanoid copepod widely distributed in coastal waters of China and Japan, and oversummering strategies may have major impacts on their population dynamics which in turn affect local marine food web structure. The abundance, stage composition, and sex composition of the planktonic copepod C. sinicus were studied from August to October 2002 in the southern Yellow Sea to understand how its population recovers from the over-summering state. Results showed that C. sinicus had low reproduction in August due to high temperature, except in waters near the Cheju Island with rich food and moderate bottom temperature, but the reproduction rates here decreased in September–October as food availability declined. When temperature dropped in September–October, C. sinicus actively propagated in coastal shallow waters. However, reproduction rates of C. sinicus individuals inhabiting the Yellow Sea Cold Water Mass(YSCWM) remained low during the three months of the study. The percentage of C. sinicus females was high during the reproductive period, which suggests that the sex composition of adult C. sinicus may reflect whether or not the population is in the reproductive mode.Numerous fifth copepodite stage(CV) C. sinicus aggregated in the YSCWM in a suspended developmental stage during the three months of this study, and they potentially served as the parental individuals for population development when conditions became optimal for reproduction later in the year. 相似文献
40.
Euphausia superba is a key species in the Southern Ocean that serves as a link between primary production and higher trophic levels. To investigate the feeding strategies of E. superba from the eastern South Shetland Islands,fatty acid biomarkers, stable isotope signatures, and an incubation experiment were conducted. The results of the incubation experiment proved that adult E. superba mainly fed on 2–20 μm particles, demonstrating the importance of nanoplankton in their diet. Moreover, significant positive relationships between δ15 N and body size demonstrated that size-related dietary shifts were present in E. superba. Evidence from principal component analysis and the C16:1ω7/C18:4ω3 ratio showed that juveniles preferentially fed on dinoflagellates and adults were more likely to feed on diatoms. Fatty acid profiles in adult E. superba roughly mirrored the different trophic conditions and feeding strategies between stations. Adult E. superba at Stas D2-07, D5-07, DA-01 and DA-02 exhibited elevated levels of C16:1ω7, C18:4ω3, C18:1ω9 and C18:1ω9/C18:1ω7, indicating higher levels of feeding on both phytoplankton and higher trophic diets. In contrast, adult E. superba at Stas D1-03 and D1-04 were characterized by high levels of polyunsaturated fatty acids/saturated fatty acids ratios and low levels of C16:1ω7,C18:1ω7, C18:4ω3, C18:1ω9 and total fatty acids. We inferred that adult krill at Stas D1-03 and D1-04 still suffered from difficult dietary conditions after overwintering. The different dietary conditions between stations suggest a highly plastic feeding strategy of E. superba in the eastern South Shetland Islands. 相似文献