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1.
A new species,Clathrocorys gracilis nov. spec. of Tripocyrtidae (Radiolarians: Nassellaria) from surface water in northern South China Sea, is described in this
paper. The new species has four radial beams arising from the cephalic base centre, each foot with cup-shaped structure and
ramified bar in the proximal section (near cephalic base), and each wing with a large mesh in the middle, a medium mesh and
a small mesh on each side respectively.
Project supported by the NSFC (No. 40276044) and the Chinese Academy of Sciences (No. KSCX2-SW-101B). 相似文献
2.
Zhu Ge-yan 《中国海洋湖沼学报》1996,14(4):308-315
The composition and distribution of benthic, periphytic and planktonic rotifers in different habitats in Krottensee were investigated.
Sixty-five rotifer taxa were identified, their relative abundance estimated.
Classification of the data set by cluster analysis allowed the recognition of distinct habitat groups confined to acid bog
ponds, macrophytes, sediments and open water. Five groups of rotifer taxa were identified on the basis of their habitat preferences
and the occurrence of the taxa. Highest diversities were found on macrophytes and in acid bog ponds. 相似文献
3.
Churyumov K. I. Klesachonok V. V. Mussaev F. A. Bikmaev I. F. Galazutdinov G. H. 《Earth, Moon, and Planets》1997,78(1-3):105-110
We present the results of the preliminary study of the comet Hale-Bopp spectrum obtained April 17, 1997 by K. Churyumov and F. Mussayev with the help of the 1-meter Zeiss reflector and the echelle spectrometer (spectral resolutionλ/Δ λ ≈ 50000), CCD and the long slit, oriented along the radius-vector(“Sun-comet direction”). Energy distributions for three selected regions including the C3, C2 (0-0) and CN(Δ ν = 0) molecules emissions of the comet Hale-Bopp spectrum were built. The rotational lines of the CN(Δ ν = 0) band were identified. The nature of the high emission peak near λ 4020 Å in the C3 band is discussed. The presence of the cometary continuum of the nonsolar origin is assumed. 相似文献
4.
Paraconchoeciadiacanthusn.sp.,anewspeciesofplanktonicOstracoda¥ChenRuixiangandLinJinghong(ReceivedApril16,19931acceptedJuly20... 相似文献
5.
The North Pacific has the world's largest groundfish fisheries, with a value in excess of $1 billion annually. The North Pacific also is home to the largest population of Steller sea lions (SSL), an ancient species that is now endangered. Decline of the western stock of SSL in the 1970–1990s coincided with the US nationalization and exponential growth in the Gulf of Alaska and Bering Sea/Aleutian Islands groundfish fishery.The article treats five aspects of the competition between the fishery and protection of the endangered species. First, we analyze competition of interests in the use, management, and preservation of the North Pacific commons, including offshore and near-shore fisheries, environmental organizations, governments (federal, state, and local), and the scientific community. Second, the article compares and contrasts provisions of the National Environmental Policy Act, the Marine Mammal Protection Act, the Endangered Species Act, and the Magnuson–Stevens Act (as amended in 1996 by the Sustainable Fisheries Act).Third, we examine the regulatory environment with a focus on the National Marine Fisheries Service (NMFS) and its relationship to the North Pacific Fishery Management Council. We illustrate how NMFS establishes fishery management plans and the methods, such as crafting biological opinions and environmental-impact-statements, it uses to resolve conflicts. Fourth, we investigate how the dual pressures on the agency—to increase fisheries production for the benefit of the industry and to preserve endangered marine species—have affected its culture (behavioral norms and operational codes). Then, the article explains agency changes in terms of crises, competition among affected interests, and development of new scientific knowledge.The article concludes by drawing lessons from the SSL controversy in the North Pacific which may pertain to national and global biodiversity conflicts. These concern the role of law in biodiversity protection, the role of science, and agency capacity for change. 相似文献
6.
ABSTRACT The genus Xenostrobus consists of small, marine and estuarine mussels that all appear similar externally. One of its estuarine species, Xenostrobus securis, with a native range in New Zealand and Australia, has become invasive in the Northern Hemisphere. No genetic data are available to determine if X. securis populations from the two countries are conspecific. Additionally, marine Xenostrobus from New Zealand have often been regarded as a species, X. neozelanicus, distinct fromthe marine Australian species X. pulex. We combined new DNA sequences with published data to assess the taxonomic status of New Zealand Xenostrobus. The data comprised 658 aligned bases of mitochondrial cytochrome c oxidase subunit I (COI) gene and 331 bases of nuclear histone H3. There was no evidence that X. securis populations from Australia and New Zealand are specifically distinct. Northern Hemisphere specimens of X. securis belonged to Australian, not New Zealand, clades in phylogenetic analyses of COI data, suggesting the former country as their more likely original source. The results confirm that X. neozelanicus and X. pulex are distinct species and for nomenclatural completeness for this taxonomic decision a lectotype is designated for Mytilus ater Zelebor in Dunker and Zelebor, 1866 [?=?Modiolus neozelanicus Iredale, 1915]. 相似文献
7.
《海洋技术学报》2024,(1)
利用传感器对水体叶绿素a 浓度进行原位测量是获取实时、连续、长时间序列数据的重要手段。本文在对RBR 传感器和ECO(Environmental Characterization Optics)传感器进行原理分析和线性度、稳定性、重复性等基本性能测试的基础上,利用单一藻种培养液和2020年南海北部海域现场数据校准传感器,并对新的传感器校准系数进行验证。结果表明:两台传感器使用新系数比原出厂系数的叶绿素a 浓度测量准确度有明显提高。RBR 传感器现场数据校准系数的计算结果与叶绿素a 标准值误差最小,平均绝对误差从1.93 μg/L 减小到0.35 μg/L,平均相对误差从55.1%减小到10.9%;ECO 传感器藻液系数明显优于出厂系数和现场数据校准系数的计算结果,平均绝对误差从1.76 μg/L 减小到0.59 μg/L,平均相对误差从50.3%减小到15.1%。传感器测量准确度的提高,可为海洋环境监测、海洋生态灾害预警等工作获取真实可靠数据提供支撑。 相似文献
8.
原子吸收光谱法和等离子光谱法分别研究了潮滩盐沼植物翅碱蓬(Suaedaheterop-tera)根际与非根际(根上部和根下部)沉积物中Cu、Zn、Pb和Cd的总量和化学形态。结果表明,从总量来看,不同潮滩沉积物中4种重金属次序均为Zn>Pb>Cu>Cd,但同一元素随潮滩位置变化明显,尤以中潮滩差异最显著,重金属总量明显大于其他两个潮滩(低潮滩和高潮滩),特别是根际沉积物中的重金属总量远高于非根际沉积物总量,其比值分别为Cu3·4—4·2倍,Zn2·2—2·7倍,Pb3·2—3·3倍。同一潮滩均表现为根际沉积物>根上部>根下部。Cd含量相对较低,其变化不明显。从化学形态看,沉积物重金属表现为环境直接影响态(交换态和有机结合态)、环境间接影响态(碳酸盐态和铁锰氧化物态)和稳定态(残渣态)。与非根际沉积物相比,根际沉积物中重金属的化学形态发生了显著的变化,Cu和Pb以稳定态为主,其次为环境间接影响态,环境直接影响态最低;Zn与上述2种金属不同,以环境直接影响态含量最高(可交换态是有机结合态的7倍),其次分别为环境间接影响态(主要是碳酸盐结合态)和稳定态。实验结果表明,由于特异根圈效应,一方面该植物使可迁移形态的Cu和Pb在根际逐步得到矿化,使其生物可利用性降低;另一方面使Zn的生物可利用性提高,促进了植物对Zn的吸收利用。 相似文献
9.
D. Jeff Ross Craig R. Johnson Chad L. Hewitt 《Estuarine, Coastal and Shelf Science》2006,67(4):695-707
The northern Pacific seastar, Asterias amurensis, was first collected in southeast Tasmania in 1986. Mistaken for the endemic asteroid Uniophora granifera, its true identity was not realised until 1992. It is now a conspicuous predator in soft sediment habitats in this region, and is considered a major threat to native assemblages and commercial species. We examined the structure of soft sediment assemblages at different spatial scales in southeast Tasmania, and correlated spatial variation in community composition with seastar abundances. We found that the structure of soft sediment assemblages is highly variable at a range of spatial scales from metres to tens of kilometres. Clear differences in the composition of assemblages and abundances of major taxa were detected between areas with and without seastars and between areas with low and high seastar densities. However, the nature of these patterns suggests that they are more likely due to differences in sediment characteristics than due to impacts of the seastar. Thus, spatial differences in soft sediment assemblages might have been erroneously attributed to seastars without detailed information on important physical factors such as sediment characteristics. A second survey, using larger sampling units (1 m2) but across a more limited spatial extent, targeted bivalves and heart urchins that were identified as important prey of the seastar in observations of feeding and in experimental studies. Large-scale patterns of abundance and size structure were consistent with seastar effects anticipated from small-scale experimental and feeding studies for some, but not all, species. While the field survey ultimately provided evidence about the presence or absence of seastar impacts at large-scales, the identification of key ecological variables in experimental and feeding studies proved crucial to both the design and interpretation of patterns observed in the large-scale surveys. Overall, this work highlighted the necessity to consider multiple lines of evidence rather than relying on a single ‘inferential’ test, in the absence of pre-impact data. 相似文献
10.