The Dynamics of Covering Behaviour in Dominant Echinoid Populations from American and European West Coasts     

Emma Verling  Anne C. Crook  & David K. A. Barnes 《Marine Ecology》2004,25(3):191-206

Abstract.  The so-called 'covering behaviour' of echinoids is known to vary with habitat according to the types of covering items available, but the full extent of the role played by habitat characteristics in this behaviour is not known. Moreover, whether or not different species inhabiting similar environmental conditions and habitats also show similar patterns of this particular behaviour has yet to be investigated. In this study, two prominent west coast echinoid species, Paracentrotus lividus and Strongylocentrotus purpuratus , were examined with respect to covering behaviour and spatial organisation. Populations of both species are found in exposed intertidal zones, occupying boreholes within tidepools. Important similarities were found in the spatial organisation of both species' populations, with lowest densities in upper shore pools. However, the size distributions of the two populations differed significantly; P. lividus within upper shore pools were significantly larger than those in mid or lower shore pools, whereas S. purpuratus on the lower shore were significantly larger than those at other shore heights. We found significant between-species variability in covering item use, although the number of covering items available at both sites was not significantly different. For example, greater densities of covering items were used by P. lividus than by S. purpuratus . We also found that the percent of echinoid surface area covered varied significantly in space for both species. These data emphasise the complex and multifaceted nature of covering behaviour, but most importantly, they also strongly suggest that habitat characteristics can only partly explain the extent of this behavioural variability amongst echinoid species.  相似文献   

Differential Colonization of Roots of Rhizophora mangle by the Wood Boring Isopod Sphaeroma terebrans as a Mechanism to Increase Root Density     

Georg  Ribi 《Marine Ecology》1982,3(1):13-19

Abstract. The frequency of parasitism of free ending prop roots of the red mangrove, Rhizophora mangle, by the wood boring isopod Sphaeroma terebrans, increased with increasing distance of the endings to established roots. In a field experiment, in which isolated endings were, surrounded by wooden sticks, the endings were colonized by S. terebrans at a lower rate than control endings, thus indicating that the wooden structures in the vicinity of the ending tended to reduce colonization rate by S. terebrans. It is concluded that S. terebrans may cause mangrove root density to increase by colonizing peripheral endings more readily than endings which are near established roots.  相似文献   

Biocorrosion by Bivalves   总被引：2，自引：0，他引：2  

Karl  Kleemann 《Marine Ecology》1996,17(1-3):145-158

Abstract. A survey of the historical background of chemically boring bivalves and the proposed methods of boring, indications for biocorrosion, observations, and experimental results are provided. The regional impact to the ecosystem is discussed with examples from the N. Adriatic, Caribbean, and E. Pacific. The fossil record of the geologically oldest biocorroders extends back into the Mesozoic, i.e ., U. Triassic for Lithophaga and Jurassic for gastrochaenids.  相似文献   

福建红树林上钻孔动物的生态   总被引：1，自引：0，他引：1  

黄戚民  周时强 《台湾海峡》1996,15(3):305-309

福建红树林上的钻孔动物共发现了５种，其中软体动物的龙骨节铠船蛆Ｂａｎｋｉａ ｃａｒｉｎａｔａ、裂铠船蛆Ｔｅｒｅｄｏ ｍａｎｎｉ和甲壳动物的光背团水虱Ｓｐｈａｅｒｏｍａ ｒｅｔｒｏｌａｅｖｉｓ是破坏红树林的主要的钻孔动物。钻孔动物钻凿红树茎的基部和裸露的根部，垂直分布受潮汐水位制约，在红树林区的纵深分布与水流畅通程度有关。  相似文献   

福州地热XG3深井应用气举反循环施工技术     

翁时瑞 《福建地质》2002,21(3):169-171

介绍了福州地热XG3深井采用气举反循环施工技术的实践过程和应用效果。  相似文献   

FW-300型非开挖导向钻机给进机构的设计   总被引：4，自引：0，他引：4       下载免费PDF全文

郑午  吴晓军 《探矿工程》2002,(2):51-52

指出了对非开挖钻机给进机构的基本要求，着重介绍了FW－300型非开挖导向钻机机构的设计思想及主要部件设计。  相似文献   

辽阳化纤公司198#住宅楼短螺旋钻孔灌注桩施工及效益分析     

徐天波  马建功  相阳秋  吴胜杰 《矿产与地质》2003,17(2):188-189

介绍了辽化198#住宅楼短螺旋钻孔灌注桩施工方法，认为该工艺具有二效快、质量好、节约材料、降低二程成本，在适当条件下，采用这种方法可收到好的效益。  相似文献   

非开挖导向钻进实际轨迹的控制设计   总被引：4，自引：0，他引：4  

张德龙  蒋荣庆 《吉林大学学报(地球科学版)》2003,33(2):246-248

非开挖导向钻进技术，具有施工速度快、适用范围广等优点，得到了广泛的应用。在实际钻进中，由于钻进在地下的不确定性，影响了导向钻进的顺利进行。到得钻进中当前点的顶角、方位角和孔深，通过均角全距法原理，可以近似地描绘出当前钻孔的空间实际轨迹，并确定钻头的位置。应用这一原理，同时运用VisualBasic语言和AutoCAD绘图工具相结合的方法，编制一套应用程序，可以直接绘制出当前钻孔轨迹，并可实现对钻孔轨迹的调控，从而保证导向钻进的顺利进行。  相似文献   

导向钻进非开挖铺管技术   总被引：5，自引：0，他引：5       下载免费PDF全文

王鹏  王洪龄  周升风  张雅春  李济武 《探矿工程》1996,(6):16-18

介绍了导向钻进非开挖铺管技术的工作原理，施工技术和工程施工实例，总结出一套导向孔轨迹设计和钻进方向控制的方法，并对我国的导向钻进非开挖技术的发展提出了建议。  相似文献   

Estimate of Loading Rate for a TBM Machine Based on Measured Cutter Forces   总被引：1，自引：1，他引：1  

Z. X. Zhang 《Rock Mechanics and Rock Engineering》2004,37(3):239-248

  相似文献