Seasonal Variation in Host Utilization of Epiphytic Lacuna Species in Mixed Algal and Surfgrass Stands in Japan

Abstract.  On the subtidal rocky shore of Akkeshi Bay, Hokkaido, Japan, the congeneric phytal gastropods, Lacuna uchidai and L. decorata , inhabit the multispecific vegetation consisting of the surfgrass, Phyllospadix iwatensis and the brown alga, Cystoseira hakodatensis . We studied the phenologies of Phyllospadix and Cystoseira , host utilization patterns and life histories of Lacuna spp. to examine how these gastropods accommodate the seasonal fluctuations of the habitat. The preferences for macrophyte by Lacuna spp. were examined by laboratory experiments. The phenologies of macrophytes, the seasonal and between-substrata variations of Lacuna spp. were examined by monthly sampling from Phyllospadix and Cystoseira beds between May 1999 and May 2000. Lacuna uchidai showed significant preference for Phyllospadix , whereas L. decorata had no preference for a particular substratum. Most L. uchidai were collected from the Phyllospadix bed, however L. decorata appeared in both Phyllospadix and Cystoseira beds. The peak of new recruit of L. uchidai coincided with that of Phyllospadix biomass. The synchronization of life cycle with the phenology of the host may be adaptive for using the limited habitat. Seasonal variation in density of L. decorata coincided with neither patterns for Phyllospadix nor Cystoseira . Seasonal variation in density and size frequency distribution suggested L. decorata migrated among adjacent macrophytes. Although it was a little vague, this hypothesis was probably the best explanation of our results. Our study shows that two co-occurring Lacuna species utilize the macrophytes as habitats by the different life histories and utilization patterns and, may be alternatively accommodated to the seasonal fluctuations of their habitats.     

荷兰海洋区测的历史与现状

回顾了荷兰区调的历史，比较了目前荷兰区测填图中不同比例尺图件的编制和应用特征；介绍了荷兰海洋区测工作中的思维方法和技术手段要点以及有关海岸带环境调查的内容。     

Distribution and Adaptations of Sea Ice Inhabiting Harpacticoida (Crustacea, Copepoda) of the Weddell Sea (Antarctica)

Abstract. Seven harpacticoid species were found to be associated with sea ice collected during 5 Antarctic cruises of the RV Polarstern. Their distribution within the fast ice and pack ice zones of the Weddell Sea is presented. Whereas some individuals probably become entrapped into the ice only accidentally, at least 4 species arc genuinely sympagic. These have evolved remarkable adaptations, as evidenced by field and laboratory studies of Dresclieriella glacialis , which is by far the most abundant. Such adaptations include: the ability to penetrate deep into ice; a comparatively high salinity tolerance allowing it to endure large salinity fluctuations associated with ice crystal formation and melting; good swimming ability, necessary both for horizontal dispersal and for a planktonic intermezzo after annual melting of the sea ice. D. glacialis is the first polar non-vertebrate mctazoan to be cultivated through its entire life cycle. Its life history suggests an r-stratcgy; this would be the first indication of such a trait in the polar environment. A new species of Drescheriella , on the other hand, exhibits resting stages (C IV-V) known to date only for Calanoidu but not reported for Harpacticoida.     

多金属结核瞬时生长速率及其意义

本文用Ｘ射线荧光光谱分析，沿结核壳层的生长方向逐点扫描测定铁锰含量，计算结核壳层的瞬时生长速率，划分结核壳层的生长阶段，计算各生长阶段的生长速率，并在结构壳层中建立高分辨率的时间标尺，重建多金属结核生长历史。     

我国东海和南海沿岸的历史风暴潮探讨

根据我国丰富的地方史志资料分析,证实在我国频临东海,南海沿岸的历史风暴潮是由台风引起的,这与冬半年出现在我国北方沿岸的风暴潮不同。列出了历朝风暴潮按月的统计和重大历史风暴潮灾害表。对史志的记载进行了探讨,指出时间记载的可靠性,古地名的变迁:随同风暴潮记载的海象、气象、天象和物象的记述;以及由风暴潮引起的次生灾害。     

东海西湖凹陷浙东中央背斜带烃源岩生排烃史研究

为了深化西湖凹陷浙东中央背斜带油气成藏过程的研究，优化勘探目标选择，在烃源岩特征分析的基础上，应用动态数值模拟技术，定量恢复了研究区主要烃源岩层系的生排烃历史，研究表明，浙东中央背斜带主要发育4套烃源岩系，其中始新统平湖组泥岩与煤层为主力烃源岩，具较高的有机质丰度=生烃强度与排烃效率，烃类排出具阶段性、多期次幕式排烃的特点汉平湖组为源岩的油气系统应是本区油气勘探的主要目标。     

Kane Fracture Zone

The Kane Fracture Zone probably is better covered by geophysical survey data, acquired both by design and incidentally, than any other fracture zone in the North Atlantic Ocean. We have used this data to map the basement morphology of the fracture zone and the adjacent crust for nearly 5700 km, from near Cape Hatteras to the middle of the Mesozoic magnetic anomalies west of Cap Blanc, northwest Africa. We use the trends of the Kane transform valley and its inactive fracture valley to determine the record of plate-motion changes, and we interpret the basement structural data to examine how the Kane transform evolved in response to changes in plate motion. Prior to about 133 Ma the Kane was a small-offset transform and its fracture valley is structurally expressed only as a shallow ( < 0.5 km) trough. In younger crust, the offset may have increased to as much as 190 km (present offset 150 km) and the fracture valley typically is up to 1.2 km deep. This part of the fracture valley records significant changes in direction of relative plate motion (5°–30°) near 102 Ma, 92 Ma, 59 Ma, 22 Ma, and 17 Ma. Each change corresponds to a major reorganization of plate boundaries in areas around the Atlantic, and the fracture-zone orientation appears to be a sensitive recorder of these events. The Kane transform has exhibited characteristic responses to changes in relative plate motion. Counterclockwise plate-motion changes put the left-lateral transform offset into extension, and the response was for ridge tips at the ridge-transform intersections to propagate across the transform valley and against the truncating lithosphere. Heating of this lithosphere appears to have produced uplift and formation of a well developed transverse ridge that bounds the inactive fracture valley on its older side. The propagating ridge tips also rotated toward the transform fault in response to the local stress field, forming prominent hooked ridges that now extend into or across the inactive fracture valley. Clockwise (compressional) changes in relative plate motion produced none of these features, and the resulting fracture valleys typically have a wide-V shape. The Kane transform experienced severe adaptions to the changes in relative plate motion at about 102 Ma (compressional shift) and 92 Ma (extensional shift), and new transform faults were formed in crust outside the contemporary transform valley. Subsequently, the transform offset has been smaller and the rates of change in plate motion have been more gradual, so transform-fault adjustment has been contained within the transform valley. The fracture-valley structure formed during extensional and compressional changes in relative plate motion can be decidedly asymmetrical in conjugate limbs of the fracture zone. This asymmetry appears to be related to the ‘absolute’ motion of the plate boundary with respect to the asthenosphere.