Abundance,distribution, and feeding patterns of juvenile coho salmon (Oncorhynchus kisutch) in the Juan de Fuca Eddy

The Juan de Fuca Eddy is a seasonal, counter-clockwise gyre off the mouth of the Strait of Juan de Fuca between Washington, USA and British Columbia, Canada that may provide favorable feeding habitat for juvenile coho salmon (Oncorhynchus kisutch) during their early marine existence. In late September 2002, physical and biological sampling was conducted along two transects of the eddy region. Surface rope trawling was conducted to capture juvenile salmon and other nekton, along with bongo and neuston net tows to examine potential mesozooplanktonic salmon prey. Presence of the Juan de Fuca Eddy was confirmed with vertical water profiles. In addition, nutrient and chlorophyll a concentrations collected from 3-m depth were within the range observed in previous studies within the eddy region. In the mesozooplankton community, euphausiids, chaetognaths, and decapod megalopae were common. In the diet of juvenile coho salmon, euphausiids and decapod megalopae were dominant by percent number, and larval and juvenile fish were dominant by percent weight. Feeding intensity (percent body weight) based on stomach contents was variable, but not significantly different among stations. To compare the Juan de Fuca Eddy region with an upwelling area, we sampled along a transect off La Push (LP), Washington, USA which is south of the eddy. The eddy region was found to be less productive than the LP transect. Nutrients were lower, chlorophyll a concentrations were higher, and zooplankton abundance was generally higher along the LP transect than in the eddy region. In addition, more juvenile coho salmon were captured from the LP transect than the eddy region. Prey items in stomachs of salmon from the LP transect were heterogeneous compared to those from the eddy region. Feeding intensity along the LP transect was slightly lower and more variable than in the eddy region, and differences in feeding intensity among LP stations were significant. In addition, feeding intensities among stations nested within regions were significantly different.     

末次冰期低纬度西太平洋硅藻席沉积与生态特征

硅藻在全球碳循环中发挥着重要的作用。"树荫种"硅藻在次表层水体中的勃发成席,并迅速埋藏成为硅藻席沉积,使人们逐渐意识到次表层生产在整个生产力及输出生产中起着重要作用。介绍了首次在低纬度西太平洋区域发现的硅藻席沉积的分布特征,硅藻席发现站位呈带状分布,大致呈北西-南东向展布,大部分散布在17.5°～20°N之间。采集到硅藻席沉积物的站位其水深在碳酸钙补偿深度(CCD)以下4837～6150m的深水区,多分布在较平坦的海底,且受风力和陆源物质输入影响相对较强的区域。该区域硅藻席的形成可能是由于末次冰期时该海区有大洋锋面的形成所致。该区域的成席硅藻Ethmodiscus rex(Wallich)Hendey为典型的"树荫种"硅藻,可以通过自身调节浮力的作用,在水体相对稳定的贫氧大洋中生存并勃发成席。末次冰期低纬度西太平洋硅藻席沉积的发生,可能使该区成为CO2的汇。     

台风对海洋叶绿素a浓度影响的定量遥感初探

研究台风对海洋水色环境的影响,是目前海洋遥感技术又一应用领域。由于台风期间天气恶劣,遥感资料较少,国际上主要针对个别典型台风,研究其对海表温度、海洋叶绿素a浓度及初级生产力的影响,很少通过遥感资料系统地对这一影响进行定量分析和建模。自2000到2007年,过境中国近海以及西北太平洋海域台风近百次,作者通过系统地分析这期间MODIS,SeaWiFS的3A级叶绿素a浓度数据,结果发现:(1)台风促进了相应海域叶绿素a浓度的大幅增长,总体上平均增长约1.426倍,个别区域在5倍以上,同时,该增长一般延后3~6d,在7~10d后恢复到原来的水平;(2)进一步对这些数据进行一元统计线性回归,发现叶绿素a浓度增长比(R_chl-a)与台风影响因子(Tsub>w)满足如下关系:R_chl-a=0.0012Tsub>w+1.017,其相关系数达0.8;(3)台风期间叶绿素a浓度与无台风时叶绿素a浓度之间有很强的线性关系,其关系满足:C_chl-a=1.2367C_0chl-a+0.0636,且相关系数高达0.98。这一初步研究结果对进一步通过遥感手段深入研究台风对海洋水色环境的影响有借鉴意义。     

Dicroerisma (Actiniscales, Dinophyceae) in the open Pacific Ocean, a gymnodinioid dinoflagellate with an endoskeleton

This study is the first to describe and illustrate the dinoflagellate genus Dicroerisma in the open Pacific Sea and in the southern hemisphere.Eleven individuals ascribed to Dicroerisma psilonereiella were encountered in subsurface waters(>70 m depth) from 34°N to 33°S.Another specimen that differs from the type is also illustrated.These findings reveal that Dicroerisma is a widespread genus and that there is tentative existence of another species within the genus.     

西太平洋暖池热含量变化与东亚冬季风关系

利用 1955-2003 年 NCEP\NCAR 再分析资料和美国 Scripps 海洋研究所环境数据分析中心 ( JEDAC ) 提供的冬季热含量资料,采用小波分析、相关及合成分析等方法, 分析了西太平洋暖池热含量变化特征及其与东亚冬季风关系.结果表明,西太平洋暖池热含量与东亚冬季风有着非常密切的联系,当西太平洋暖池热含量异常偏高时,对流层低层在菲律宾及以东洋面形成一个异常的气旋性环流,中国大陆上空形成一个异常的反气旋性环流,从而使得东亚冬季风在东南区加强,西北区减弱.     

影响山东热带气旋活动的气候特征与太平洋海温的关系

利用1949～2003年热带气旋年鉴资料,对55年来影响山东热带气旋(TC)活动的气候特征与太平洋海温的关系进行了分析.结果表明:(1)在厄尔尼诺年,影响山东的TC频数较常年明显偏少.厄尔尼诺次年TC频数较常年稍有增加;拉尼娜年影响山东的TC频数较常年显著偏多,增加明显的月份主要是8月和9月,拉尼娜次年,影响山东TC频数偏少.厄尔尼诺事件强度越大,影响山东的TC频数越少;(2)影响山东的TC数和菲律宾以东洋面的海温呈正相关,并具有很好的持续性.影响山东的TC多年,赤道中东太平洋有较强的负距平区,影响山东的TC少年,赤道中东太平洋为正距平区;(3)厄尔尼诺年,影响山东的TC强度偏强.拉尼娜年,影响山东的TC强度明显偏弱.影响山东的TC强度厄尔尼诺年要比拉尼娜年强很多;(4)影响山东TC偏强年在赤道中东太平洋有较强的正距平区,影响山东TC偏弱年在赤道中东太平洋地区有较强的负距平.综上说明赤道中东太平洋的海温高低对影响山东的TC频数和强度有较好的指示作用.     

赤道西太平洋末次盛冰期以来的浮游有孔虫氧碳稳定同位素记录

对西太平洋暖池核心区MD01—2386柱状样最上部5m进行了高分辨率的浮游有孔虫Globigerinoides ruber和Pulleniatina obliquiloculata的氧、碳稳定同位素分析,结合AMS^14C测年,研究表明其属于末次盛冰期-全新世的沉积。赤道西太平洋海区末次盛冰期以来δ^18O值显著降低,但有几次回返事件。表层浮游有孔虫G．ruber比次表层温跃层属种P．obliquiloculata对于环境变化的响应要快,但后者变化的幅度较大。这两个种的氧、碳同位素差值反映出温跃层深度自末次盛冰期以来逐渐加深,并存在周期性的回返事件,说明西太平洋暖池晚第四纪冰期旋回存在气候不稳定性。     

Coral assemblages and reef growth in the Commonwealth of the Northern Mariana Islands (Western Pacific Ocean)

Reef development varies considerably around the high, raised‐limestone islands of the Commonwealth of the Northern Mariana Islands (CNMI). Here we examine the modern assemblages at 30 sites for coral composition, colony density, colony size, and fidelity. We defined four reef types and hypothesize the presence of environmentally driven ecological stasis, whereby the environment continuously selects for coral species membership, defines colony sizes, and over time creates the noted reef types. Our results show that constructional spur‐and‐groove reefs supported significantly larger coral‐colony sizes and higher coral species richness compared with high‐relief interstitial framework, low‐relief incipient, and non‐constructional coral assemblages. Non‐constructional reefs supported much smaller coral colony sizes, despite similar population densities, and were consistently found in association with high wave exposure. The distinct coral assemblages found on interstitial framework and low‐relief incipient reefs were not affiliated with any wave exposure regime, but were located adjacent to large watersheds and on islands with unique geological history. These assemblages were nested within the spur‐and‐groove species pool. Overall, modern coral cover was well predicted by bathymetric slope and watershed size, while species richness was additively influenced by two proxies of pollution, suggesting the latter is better suited for establishing management targets. In contrast with previous studies that suggested modern assemblages were biologically controlled in the CNMI, we show reef assemblages and reef development are highly influenced by long‐term environmental forcing.     

西秦岭金矿类型及成矿区带划分

西秦岭是我国西北地区主要的金矿集中区 ,也是陕甘川“金三角”的重要组成部分。区内金矿床 (点 )遍布 ,形成以构造破碎蚀变岩型为主 ,硅灰泥岩型、石英脉型次之 ,兼有绿片岩型、接触交代型及河床—河漫滩堆积型等 6种金矿床类型。依据构造带及金矿床 (点 )的展布 ,初步划分为 10个Ⅴ级成矿带。通过揭示金矿带区域成矿地质构造特征 ,指出了西秦岭进一步找矿方向     

Tektonisches Verhalten und geologische Bedeutung von Kalksilikatfels-Lagen und -Spindeln im Damara-Orogen Südwest-Afrikas

Zusammenfassung Beschrieben wird das Verhalten von frühdiagenetisch gebildeten schichtparallelen Kalksilikatfels-Lagen, -Linsen, -Knollen und diffusen Ansammlungen während der Gesteinsdeformation in Teilen des Damara-Orogens. In Abhängigkeit von ihrer relativen Löslichkeit und/oder Kompetenz sowie vom Winkel zwischen Schichtung und Schieferung können Lagen und Linsen als solche erhalten bleiben oder in spindelförmige Körper zerlegt werden (Verkürzungsboudinage). Knollen werden zu Ellipsoiden oder Spindeln deformiert und diffuse Kalksilikatfels-Ansammlungen in eine Vielzahl von Spindeln aufgelöst. Alle im Zusammenhang mit der Anlage der Schieferung gebildeten Spindeln und Ellipsoïde sind streng in der Schieferung orientiert. Es wird deutlich, daß die Spindelform der Kalksilikatfels-Körper ein Produkt der Gesteinsdeformation ist.In Gebieten, in denen der Verdacht besteht, daß parallel zu einem deutlichen Materialwechsel eine Schieferung verläuft, kann aus der Existenz von Spindeln auf das Vorhandensein dieser Schieferung geschlossen werden.Die ungleichmäßige Verteilung von Kalksilikatfels-Körpern innerhalb der Khomas-Serie ermöglicht eine Unterteilung dieser bisher ungegliederten, bis zu 6000 m mächtigen Gesteinsfolge.

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The behaviour during rock deformation of diagenetically formed layers, lenses, nodules (concretions) and diffuse concentrations of calc-silicate rock is described from parts of the Damara belt. Depending on their relative solubility and/or competency and on the angle between bedding and cleavage planes the layers and lenses may either more or less retain their shape or be cut up into spindle-shaped bodies (boudinage due to shortening). Nodules are deformed to ellipsoides, while diffuse concentrations of calc-silicate rock are transformed into a number of spindles. All spindles and ellipsoides which are formed during the formation of the cleavage are strictly orientated parallel to the cleavage planes. It is therefore obvious that the spindleshape of these bodies is a consequence of rock deformation. Thus, in areas in which a cleavage is suspected to lie parallel to a distinct bedding, the occurrence of spindles may confirm the existence of this cleavage.The non-statistical occurrence of calc-silicate rock bodies within the Khomas Series may render possible a first subdivision of this up to 6000 m thick succession.

Diese Arbeit ist im Sonderforschungsbereich 48 Entwicklung, Bestand und Eigenschaften der Erdkruste, insbesondere der Geosynklinalräume, Göttingen, entstanden.