An overview of the Oyashio ecosystem   总被引：3，自引：0，他引：3  

Yasunori Sakurai   《Deep Sea Research Part II: Topical Studies in Oceanography》2007,54(23-26):2526

The Oyashio shelf region and the seasonally ice-covered areas north of Hokkaido are highly productive, supporting a wide range of species including marine mammals, seabirds and commercially important species in the western subarctic Pacific. The fishes include gadids, such as walleye pollock and Pacific cod, and subarctic migratory pelagic fishes such as chum salmon and pink salmon. It is also an important summer feeding ground for subtropical migrants such as the Japanese sardine, Japanese anchovy, Pacific saury, mackerels, Japanese common squid, whales and seabirds. In recent decades, some components of the Oyashio ecosystem (i.e., phytoplankton, mesozooplankton, gadid fish, and subtropical migrants) have shown changes in species abundance or distribution that are correlated with environmental changes such as the 1976/1977 and 1988/1989 regime shifts. The First Oyashio Intrusion moved northward from the mid-1960s until the late 1970s, when it moved southward until the 1980s, after which it returned to the north again after the mid-1990s. The sea-surface temperature in spring decreased after the late 1970s, increased after the late 1980s, and remained high during the 1990s. The extent of ice cover in the Sea of Okhostk also decreased during the latest warming in the 1980–1990s but has increased again since the late 1990s. This and other variabilities affect the Oyashio ecosystem and the surrounding region.  相似文献   

南沙海区中生界岩相分布及构造特征   总被引：3，自引：0，他引：3       下载免费PDF全文

刘海龄  谢国发  阎贫  刘迎春  郑红波 《海洋与湖沼》2007,38(3):272-278

为了了解南中国海南部南沙群岛陆架-陆坡区中生代地层发育情况,作者通过综合分析该海区钻井、拖网及1987年以来采集的20000多公里的多道反射地震勘探等资料,得到了对该区中生界基本特征的如下新认识:空间分布上,南沙的中生界具有从北部的郑和-礼乐隆起南缘向南增厚的趋势;沉积岩相方面,东部三叠纪时为深海相,侏罗纪为浅海与三角洲相,白垩纪为浅海-内浅海相,而往西南部中生代的海水深度有变深的趋势;中-新生代变形上,在南沙西部的曾母盆地,中生界褶皱为复式的、非协调性的,南沙中部多为舒缓褶皱,东部仅在近巴拉望海槽地带出现小幅度的褶皱。结合围区中生界及特提斯构造域的发育特征,作者提出南沙地块上的海相中生界在大地构造上归属于残留在中特提斯洋北部减薄陆缘地壳上的中特提斯期海相沉积地层,是该海域油气资源勘探不可忽视的对象。  相似文献   

Heavy metals in marine sediments of Taranto Gulf (Ionian Sea, Southern Italy)   总被引：5，自引：0，他引：5  

Alessandro Buccolieri  Giovanni Buccolieri  Nicola Cardellicchio  Angelo Dell'Atti  Antonella Di Leo  Antonella Maci 《Marine Chemistry》2006,99(1-4):227

Al, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Ti and Zn concentrations have been determined in surface sediment samples collected in the Taranto Gulf (Ionian Sea, Southern Italy) in order to evaluate their levels and spatial distribution in this important area of the Mediterranean Sea. For various metals, the geoaccumulation index has been calculated as a criterion to assess if their concentrations represent contamination levels or can be considered as background levels. The results show that metals concentrations in sediments can be considered near the background levels found in the Mediterranean Sea.Analytical results have been elaborated by using a Geographical Information System (GIS) software to show metals accumulation areas. Using multivariate statistical analysis, we evaluate the possibility to distinguish the sampling stations, in relation to their geographical position. Results have showed metals distribution in the Taranto Gulf is principally influenced by industrial and urban wastes, located mostly in the northern coastal area of the Ionian Sea. Rivers in the Basilicata region and prevailing anticlockwise marine currents are further factors influencing metal accumulation in sediments.  相似文献   

Symbiotic Relations of Sediment-Agglutinating Nematodes and Bacteria in Detrital Habitats: The Enzyme-Sharing Concept   总被引：2，自引：0，他引：2  

Franz Riemann  & Elisabeth Helmke 《Marine Ecology》2002,23(2):93-113

Abstract. A new concept (‘enzyme sharing’) concerning the interaction of marine nematodes and microbes in the degradation of sedimentary detritus is presented. Elements of this concept are (1) the notorious tendency of many aquatic nematodes to agglutinate detrital particles by mucus secretions, (2) new observations on the stimulation of microbial growth by nematodes in agar plates, and (3) literature data on limited endogenous proteolytic capacities of aquatic nematodes.
Observations on nematode‐microbe associations in agar plates prompted the conceptual synthesis. In agar medium without the addition of any nutrients a spectacular growth of bacteria was visible on the sinusoidal crawling trails of nematodes only 2 – 3 days after introduction of the worms (species of Adoncholaimus, Anoplostoma and Sabatieria). Juveniles of Anoplostoma that hatched in the agar cultures left their minute trails in the medium and these were rapidly occupied by bacteria. The nematodes repeatedly visited their bacterial trails, which persisted as a peculiar biotic structure for more than one year and survived the nematodes.
In sterile agar preparations containing the fluorogenic methylumbelliferyl‐β‐glucoside in the presence of the nematode Adoncholaimus, an enhanced fluorescence of the medium was visible, indicating β‐glucosidase activity. We therefore assume that oncholaimid nematodes discharge enzymes that alone, or in concert with microbial activities, contribute to the hydrolytic cleavage of refractory polysaccharides containing β‐glucosidic bonds such as agar components and cellulose. The sugars thus produced may then be taken up by the nematodes and concomitantly support the conspicuous growth of microbes. Since we did not observe any feeding of the nematodes on the associated microbes in agar plates, we question the nutritive potential of intact microbial cells for a number of nematodes abounding in detrital habitats, and call attention to the significance of ambient dissolved or adsorbed organic monomeric nutrients.
Consequently, we perceive the puzzling perpetual accretion of detrital organic particles to sediment agglutinations by nematodes as an adaptation for operating an ‘enzymatic reactor’ for the production of dissolved nutrients. We hypothesise a relationship of mutual commensalism of nematodes and heterotrophic microbes in detrital habitats and propose the term ‘enzyme sharing’ for this relationship. Both parties invest in a common enzyme pool that decomposes organic detritus for their nutrition. We present here evidence that nematodes contribute β‐glucosidase, which is involved in the cellulase system. Data from the literature suggest that microbial enzymatic processing of detrital proteins yields amino acids available to nematodes, which apparently have no efficient proteolytic enzyme system in their intestines.  相似文献   

海洋植物营养素的应用研究　Ⅰ.金藻类的培养     

龙丽娟  孙恢礼  何伟宏 《热带海洋学报》1998,(1)

用不同含量的93－B型海洋植物营养素对几种常用的金藻类饵料种进行培养对比试验。结果表明,海洋植物营养素用于培养金藻类效果良好,最适使用含量为30mp·L~-1域40mg·L~-1。此时效果与通常被推荐的培养液所培养的对照组相当或更好．含量过高,则造成某些营养盐过量而产生一定的毒害作用。此营养素使用简便。  相似文献   

海洋细菌对赤潮藻生长及其产毒量的影响   总被引：5，自引：2，他引：5       下载免费PDF全文

苏建强  郑天凌  俞志明  宋秀贤 《海洋与湖沼》2003,34(1):44-49

采用麻痹性贝类毒素小白鼠生物测定法 ,研究了在可控生态条件下两株海洋细菌S1 0 、P42 对塔玛亚历山大藻生长及其产毒量的影响。结果表明 ,菌株S1 0 在较高浓度下对藻细胞的生长有明显的抑制作用 ,在较低浓度下抑藻生长作用较弱 ,不同浓度的菌株S1 0 均能有效地抑制藻细胞内麻痹性贝类毒素的产生 ,且在较低浓度下效果较好 ;菌株P42 对该藻的作用恰好与S1 0 相反 ,在较低浓度下明显抑制藻细胞的生长 ,不同浓度的菌株P42 也能有效地抑藻产毒 ,且在较高浓度下作用较明显。实验用的藻株毒力约为 ( 0 .95— 1 2 .1 4)× 1 0 - 6MU/cell,属于低毒藻株 ,该藻株在培养第 1 4天达到毒性最高峰 ,峰值为 1 2 .1 4× 1 0 - 6MU/cell,之后逐渐下降。讨论了海洋细菌在赤潮生物防治中的应用前景  相似文献   

Sublittoral meiofauna with particular reference to nematodes in the southern Yellow Sea, China   总被引：6，自引：0，他引：6  

Xiao-Shou Liu  Zhi-Nan Zhang  Yong Huang   《Estuarine, Coastal and Shelf Science》2007,71(3-4):616-628

Densities of major meiofaunal taxa were investigated at 34 sampling stations during six cruises by R/V Beidou to the southern Yellow Sea, China from 2000 to 2004, and the community structure of free-living marine nematodes was studied during one of the cruises in 2003. Meiofauna abundance ranged from 487.4 to 1655.3 individuals per 10 cm². Nematodes and harpacticoid copepods were the two most dominant groups, contributing 73.8–92.8% and 3.5–18.7%, respectively, to the total meiofauna abundance. One-way ANOVA showed no significant annual fluctuation of meiofauna and nematode abundances from 2000 to 2004 in the southern Yellow Sea. However, two-way ANOVA based on six stations sampled in 4 years (2001–2004) showed that there were significant differences among the six stations and the 4 sampling years for meiofauna, nematode and copepod abundance. Correlation analysis demonstrated that meiofauna abundance was mainly linked to chloroplastic pigments. Other environmental factors could not be ruled out, however. A total of 232 free-living marine nematode species, belonging to 149 genera, 35 families and 4 orders, were identified. The dominant species in the sampling area were the following: Dorylaimopsis rabalaisi, Microlaimus sp.1, Prochromadorella sp., Promonohystera sp., Cobbia sp.1, Daptonema sp.1, Leptolaimus sp.1, Halalaimus sp.2, Aegialoalaimus sp., Chromadorita sp., Parodontophora marina, Parasphaerolaimus paradoxus, Quadricoma sp.1, Campylaimus sp.1, Halalaimus gracilis, Paramesacanthion sp.1, Paramonohystera sp.1, and Metalinhomoeus longiseta. CLUSTER and SIMPROF analyses revealed three main types of nematode community (or station groups) in the sampling area, including I: coastal community, II: transitory community between coastal and YSCWM (Yellow Sea Cold Water Mass), and III: YSCWM community. Each community was indicated by a number of dominant nematode species. Bio-Env correlation analysis between the nematode community and environmental variables showed that water depth, sediment water content, organic matter, chlorophyll a (Chl-a) and phaeophorbide a (Pha-a) were the most important factors to determine the community structure.  相似文献   

厦门港湾和闽南-台湾浅滩海域鱼类感染吸虫的调查研究   总被引：1，自引：0，他引：1  

曹华 《台湾海峡》1991,(2)

本文根据1980～1986年厦门港湾和闽南-台湾浅滩海域的调查资料,报道了该海区鱼类感染复殖吸虫的概况。在我们检查的106种鱼类中,从其中54种的消化道和1种的体腔中发现复殖吸虫标本1269个,感染率为28.24%。本海区鱼类生态习性虽有差异,其感染率和阳性鱼的感染度可能有明显差异,但从总体上看,不同生态类群鱼类的吸虫密度分布甚为均匀。  相似文献   

Morphogenetic studies on Uronychia uncinata(Protozoa, Ciliophora) during its asexual division     

Song Weibo 《海洋学报(英文版)》1996,15(1):93-99

ＭｏｒｐｈｏｇｅｎｅｔｉｃｓｔｕｄｉｅｓｏｎＵｒｏｎｙｃｈｉａｕｎｃｉｎａｔａ（Ｐｒｏｔｏｚｏａ，Ｃｉｌｉｏｐｈｏｒａ）ｄｕｒｉｎｇｉｔｓａｓｅｘｕａｌｄｉｖｉｓｉｏｎ￥ＳｏｎｇＷｅｉｂｏ（ＲｅｃｅｉｖｅｄＡｕｇｕｓｔ２８，１９９５；ａｃｃｅｐｔｅｄ...  相似文献   

Molecular identification of ascaridoid nematodes from the deep-sea onion-eye grenadier (Macrourus berglax) from the East Greenland Sea   总被引：2，自引：0，他引：2  

Esra Kellermanns  Sven Klimpel  Harry Wilhelm Palm 《Deep Sea Research Part I: Oceanographic Research Papers》2007,54(12):2194-2202

Macrourus berglax from the East Greenland Sea was studied for the presence of ascaridoid nematodes in 2001, 2002 and 2003. The fishes were collected between 278 and 413 m water depth using a benthopelagic net. Based on the amplification of the internal transcribed spacer ITS-1, 5.8S, ITS-2 and flanking sequences (=ITS+), three ascaridoid nematode species were identified. The prevalence of infestation during the 3 years ranged from 42.9% to 62.9% and 22.9% to 40.0% for the anisakids Anisakis simplex (s.s.) and Pseudoterranova decipiens (s.s.), respectively, and from 28.6% to 60.0% for the raphidascarid Hysterothylacium aduncum. A total of 18 specimens, two of each species and examination year, revealed no sibling species, suggesting a limited distribution of other ascaridoid siblings into the deep sea. The ITS-1, 5.8S and ITS-2 sequences of A. simplex (s.s.) from the East Greenland Sea did not differ from previously published sequence data (GenBank) from other regions in the Atlantic and Pacific oceans. The sequences of P. decipiens (s.s.) corresponded most closely to those of specimens from Richardson Bay, western Pacific, and differed in four positions (0.5%). They corresponded least to those of specimens from Japan (1.5%). The sequence data for H. aduncum differed in two positions in the ITS-1 (0.2%) and three positions in the ITS-2 (0.3%) from sequences from Japan. A high genetic similarity between the regions can be explained by (a) extensive final host migration in the case of A. simplex (s.s.), (b) an overlapping distribution of final host populations along the continental shelves for P. decipiens (s.s.) and (c) a low host specificity and large population size in the intermediate and final hosts for H. aduncum. The occurrence of the identified species in the macrourid fish underlines the potential of cosmopolitan ascaridoid nematodes to distribute not only horizontally but also vertically in the deep sea.  相似文献